Lysosomal Disease Program Harvard Medical School
    MGH LSD Home > Glossary
Disease List
 Gaucher
 Fabry
 Pompe
 MPS I
 MPS II

Make an Appointment
News and Upcoming Events















Contacts I Glossary

 
 


Glossary


A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z


A

ACE:  An abbreviation for angiotensin-converting enzyme. ACE is a vasoconstricting enzyme that causes a narrowing of the blood vessels which restricts blood flow.

Acroparesthesia:  The burning pain in the hands and feet that a Fabry patient experiences. This pain can radiate up the extremities.

Affected:  An individual who manifests symptoms of a particular condition

Albumin:  A water-soluble protein found in most tissues. Albumin levels are often used in many diagnostic tests. The constant presence of albumin in the urine usually indicates kidney disease.

Allele:  Any one of two or more genes occupying the same location on a chromosome, determining a given trait (such as eye color, production of a particular enzyme, etc.).

Alpha Galactosidase: A (alpha-GAL):  The enzyme that is either missing or exists in less than adequate amounts in people with Fabry disease that is necessary to break down a particular substrate.

Amniocentesis:  Withdrawal of fluid from the amniotic sac, the innermost membrane surrounding the fetus containing amniotic fluid. Can sometimes be used to obtain samples for prenatal diagnosis of certain LSDs.

Anemia:  Low red blood cell count, which often results in fatigue, lethargy, and other symptoms.

Angioedema:  An accumulation of fluid under the skin, usually due to an allergic response.

Angiokeratoma:  Purplish-blue skin rash that may be a symptom with several LSDs.

Anhidrosis:  The inability to sweat. Many Fabry patients experience anhidrosis.

Antibody:  A type of protein that is part of the immune system. Antibodies recognize and attach themselves to infectious organisms and foreign materials so they can be removed from the body.

Assay:  A laboratory procedure to determine the activity of an enzyme isolated from a patient when compared to normal, or the amount of a particular substance found in blood or urine that may be present in excessive amounts.

AST and/or ALT:  Abbreviations for enzymes involved in specific metabolic processes; blood levels of these enzymes are used as diagnostic aids in viral hepatitis and myocardial infarction. AST is the abbreviation for aspartate transaminase (the term formerly used was SGOT) and ALT is the abbreviation for alanine aminotransferase (the term formerly used was SGPT).

Asymptomatic:  Descriptive term for a person who does not appear to be affected by their disease (i.e., displays no symptoms); in context of genetic diseases the person may be a carrier.

Autosomal recessive disorder:  A genetic disease caused by a gene mutatation on an autosome (non-sex-related chromosome), caused when an individual inherits the mutated gene from both parents.

Avascular necrosis:  Death of the cells in a bone or joint due to a loss of blood flow. Avascular necrosis may result from blockage of blood vessels inside a weakened and collapsing bone.

Azotemia:  An excessive amount of nitrogen bodies in the blood, resulting from kidney insufficiency.

TOP


B

Base pair:  (synonym: bp) Two Nitrogenous bases paired together in double-stranded DNA by weak bonds; specific pairing of these bases (adenine with thymine and guanine with cytosine) facilitates accurate DNA replication: wehn quantified (e.g., 8 bp), referes to the physical length of a sequence of nucleotides

Benign variant:  (synonym: polymorphism) An alteration in gene distinct from the normal, wild-type allele that does not appear to have deleterious effect

Biochemical marker:  A substance whose detection indicates a biochemical (chemical, molecular, and physical) activity or change in the body, its tissues or cells; the biochemical marker may be monitored in the assessment of a disorder or condition.

Bone crisis:  An episode of intense, acute pain that may last for hours to days and maybe accompanied by local and/or systemic fever. A bone crisis occurs when there is a lack of oxygen in an area where Gaucher cells have interfered with normal blood flow.

Bone lesion:  An abnormality of bone tissue usually visible using imaging techniques.

Bone marrow transplant:  See hematopoietic stem cell transplant (HSCT).

TOP


C

Cardiomyopathy:  An enlargement of the heart.

Carrier:  A person who possesses at least one gene that may contribute to disease in offspring.

Carrier Testing:  (synonyms: carrier detection, heterozygote testing) Testing used to identify usually asymptomatic individuals who have a gene mutation for an autosomal recessive or X-linked recessive disorder

Catabolic:  The metabolic process in which materials are broken down.

Cell:  The smallest structural unit of the body, capable of performing all the key functions of life (digestion, reproduction, waste disposal, etc.).

Ceramide:  A complex lipid. An example is glucocerebroside, which is composed of ceramide and glucose.

Chitotriosidase:  An enzyme in the group known as chitinases that metabolize very complex sugar molecules; it is considered a biochemical marker of Gaucher disease. Gaucher cells, as activated macrophages, were determined to be a source of chitotriosidase with the demonstration of massive secretion of the enzyme by cultured macrophages containing accumulated glucocerebroside.

Chorionic villi:  Tiny membrane projections in the developing placenta (the tissue that connects the umbilical cord to the uterus). Cells samples can sometimes be obtained from the chorionic villi and used for prenatal diagnosis of certain LSDs

Chromatography:  A technique used to separate complex mixtures.

Chromosome:  A threadlike strand of DNA and associated proteins in every plant and animal cell. Chromosomes carry the genes that define a person's bodily makeup (e.g., hair and eye color, disease expression). Every cell in the body contains an identical set of 46 chromosomes, grouped into 23 pairs.

Chronic granulocytic leukemia:  A mixed group of disorders in the formation of blood cells in the bone marrow

Cirrhosis:  Liver disease at an advanced stage with widespread damage to the cells of the liver such that there is loss of liver function and interference with blood flow in the liver.

Coding region:  (synonym: open reading frame) All exons of a gene that contribute to the protein product(s) of the gene

Codon: In DNA or RNA, a sequence of three nucleotides that codes for a certain amino acid or signals the termination of translation (stop or termination codon)

 

Collapsed vertebra:  A crushed or contracted bone in the spinal column, usually resulting from a chronic disease that has led to a decrease in bone density and strength.

Congenital:  Existing at birth; referring to certain mental or physical traits, malformations, or diseases, which may be hereditary or due to an influence occurring during gestation (in utero).

Conjunctival:  Involving the fine cell layer covering the eye and inner surface of the eyelids.

Corneal Opacities:  Clouding in the cornea, usually a sign of Fabry disease.

Corneal Verticullata:  Whorl-like opacities in the cornea.

Contraindication:  Any factor prohibiting the use of a particular procedure or drug for a specific patient because of the likelihood of unwanted results.

Creatinine Clearance:  Clearance of toxic buildup in the kidney.

Critical region:  The specific portion of a chromosome or a gene that, when altered in some way (deleted, duplicated, or otherwise mutated), produces the characteristic set of phenotypic abnormalities associated with a particular syndrome or disorder

TOP


D

De novo mutation:  (synonyms: de novo gene mutation, new gene mutation, new mutation) An alteration in a gene that is present for the first time in one family member as a result of a mutation in a germ cell (egg or sperm) of one of the parents or in the fertilized egg itself

Deletion:  Absence of a segment of DNA; may be as small as a single base or as large as one or more genes

DEXA (dual energy X-ray absorptiometry):  A bone scan test used to measure bone density.

Diagnostic testing:  Testing designed to confirm or exclude a known or suspected genetic disorder in a symptomatic individual or, prenatally, in a fetus at risk for a certain genetic condition

Direct DNA analysis:  (synonym: direct DNA) The use of any test method, such as sequence analysis, mutation scanning, or mutation analysis to detect a mutation in a gene

Disease-causing mutation:  A gene alteration that causes or predisposes an individual to a specific disease

DNA (deoxyribonucleic acid):  Chemical molecules that contain all a person's genetic materials and from which chromosomes and genes are constructed.

 

DNA-based testing:  (synonyms: DNA testing, molecular genetic testing) Testing that involves the analysis of DNA, either through linkage analysis, sequencing, or one of several methods of mutation detection

DNA Sequencing:  A laboratory procedure that determines the order of base pairs in a segment of DNA.

Dorsal Root Ganglia:  Nerve bundles located at the back of the spine.

Domain:  A specific region or amino acid sequence in a protein associated with a particular function or corresponding segment of DNA

Dominant:  A genetic trait that is expressed even if only one gene in the pair code for it; it will "override" a gene that codes for a recessive trait.

TOP


E

Enzyme:  A type of protein that facilitates chemical changes in other substances. LSDs are caused by the deficiency or malfunction of certain enzymes in the body.

Enzyme assay:  Definitive test used to diagnose most LSDs. Enzyme levels are analyzed in a tissue sample taken from the patient and compared to known normal levels. Lower-than-normal levels for certain enzymes provides a conclusive diagnosis for the LSD associated with the enzyme.

Enzyme replacement therapy (ERT):  A form of treatment used for some LSDs in which patients get an intravenous infusion to replace the missing or faulty enzyme causing the LSD.

Exon:  Coding sequence of DNA present in mature messenger RNA

Exogenous:  created outside of the body

TOP


F

Fabry Crisis:  episodic agonizing incapacitating pain that can last minutes to days

False negative result:  A test result which indicates that an individual is unaffected and/or does not have a particular gene mutation when he or she is actually affected and/or does have a gene mutation; i.e., a negative test result in an affected individual

False positive result:  A test result which indicates that an individual is affected and/or has a certain gene mutation when he or she is actually unaffected and/or does not have the mutation; i.e., a positive test result in a truly unaffected individual

Familial:  A phenotype that occurs in more than one family member; may have genetic or non-genetic etiology

Family history:  The genetic relationships and medical history of a family; when represented in diagram form using standardized symbols and terminology, usually referred to as a pedigree Related Terms: pedigree

Family-specific mutation: In a family, the sequence alteration observed that causes or predisposes to a particular disease; the mutation may be rare or common

Fibrosis:  The formation of fibrous tissue in a repair or reactive process, as opposed to formation of fibrous tissue as a normal part of the tissue or organ.

 

First-degree relative:  Any relative who is one meiosis away from a particular individual in a family (i.e., parent, sibling, offspring)

Founder effect:  A gene mutation observed in high frequency in a specific population due to the presence of that gene mutation in a single ancestor or small number of ancestors

Frameshift mutation:  (synonyms: out-of-frame deletion, out-of-frame mutation) An insertion or deletion involving a number of base pairs that is not a multiple of three and consequently disrupts the triplet reading frame, usually leading to the creation of a premature termination (stop) codon and resulting in a truncated protein product

TOP


G

Gaucher cell:  A cell containing excess glucocerebroside, which accumulates in the lysosomes because of a lack of the enzyme glucocerebrosidase.

Gene:  The basic unit of heredity, consisting of a segment of DNA arranged in a linear manner along a chromosome. A gene codes for a specific protein or segment of protein leading to a particular characteristic or function. Related Terms: allele; genome; genotype; mutation

Genes:  Pieces of DNA that occupy specific locations on chromosomes and that control different activities and details of a person's makeup and function (e.g., eye color, production of certain enzymes, etc.).

Gene product:  Genes are transcribed into segments of RNA (ribonucleic acid), which are translated into proteins. Both RNA and proteins are products of the expression of the gene.

Gene Defects:  Change in the unit of the heredity, usually resulting in the expression of a disease, also called a mutation. Mutations usually disrupt the structure of a protein. In the case of an enzyme, this change may result in the loss of function.

Gene therapy:  Potential treatment for LSDs, currently in experimental stages, that involves replacing the patient's mutated gene with a normal copy.

Genetic:  Affecting or affected by genes (such as a genetic disease); genetic material is inherited by children from their parents.

Genetic counseling:  A process, involving an individual or family, comprising: evaluation to confirm, diagnose, or exclude a genetic condition, malformation syndrome, or isolated birth defect; discussion of natural history and the role of heredity; identification of medical management issues; calculation and communication of genetic risks; provision of or referral for psychosocial support

Genetic counselor:  An expert in genetic disorders who provides information about the risk and difficulty of a disorder to patients or relatives in families with genetic disorders as an aid to making informed decisions about marriage, children, early diagnosis, and prognosis.

Genetic predisposition:  (synonym: genetic susceptibility) Increased susceptibility to a particular disease due to the presence of one or more gene mutations associated with an increased risk for the disease and/or a family history that indicates an increased risk for the disease

Geneticist:  A physician who specializes in genetics, the study of heredity and variation of organisms.

Genome:  The complete DNA sequence, containing all genetic information and supporting proteins, in the chromosomes of an individual or species

Genotype: The genetic make-up of an individual's cells. The genotype together with the biologic environment produce the phenotype, or the outward manifestations.

 

Genotype-phenotype correlation: The association between the presence of a certain mutation or mutations (genotype) and the resulting pattern of abnormalities (phenotype)

Germline: The cell line from which egg or sperm cells (gametes) are derived

Germline mutation: The presence of an altered gene within the egg or sperm (germ cell), such that the altered gene can be passed to subsequent generations

Globotriaosylceramide:  Also known as GL-3. The fatty compound that accumulates in the blood vessel wall of people with Fabry disease. Fabry patients do not produce adequate amounts of alpha galactosidase, the enzyme that breaks down the globotriaosylceramide.

Glomerular Filtration Rate:  (GFR) A measurable volume of filtration in the glomerulus.

Glucocerebrosidase:  The enzyme that is deficient in people with Gaucher disease. It breaks down glucocerebroside into glucose and ceramide.

Glucocerebroside:  A type of fat (lipid) molecule that accumulates in individuals with Gaucher disease. Also called glucosylceramide.

Glucose:  A simple sugar that is the major energy source in the body.

Glucosylceramide:  Another name for glucocerebroside.

Glycosphingolipid:  A fatty substance. There are many different types of glycosphingolipids; in the case of Gaucher disease, certain glycosphingolipids can not be broken down and accumulate due to an enzyme deficiency.

TOP


H

Hematologic:  Of or pertaining to the blood and bone marrow.

Hematopoietic stem cell transplantation (HSCT):  A form of treatment used for some LSDs in which healthy stem cells (usually taken from bone marrow, sometimes from cord blood)[3] are intravenously transplanted into a patient to produce the faulty or missing enzyme (and create additional healthy cells).

Hemoglobin:  A component of red blood cells that transports oxygen from the lungs to other tissues in the body.

Hemiplegia:  Paralysis of one side of the body

Hemizygote:  The male is hemizygote for the X-chromosome. (he has only one copy of the chromosome X).

Hepatomegaly:  Enlargement of the liver; may be a symptom with several LSDs.

Hepatosplenomegaly:  Enlargement of the liver and spleen; may be a symptom with several LSDs.

Heterogeneous:  Consisting of dissimilar elements or parts; varied

Heterozygote:  Organism carrying two different alleles of the same gene.(see carrier.)

Homologous chromosomes:  (synonym: homologs) The two chromosomes from a particular pair, normally one inherited from the mother and one from the father, containing the same genetic loci in the same order

Homozygote:   An individual who has two identical alleles at a particular locus, one on each chromosome of a pair

Hypertrophy:  The enlargement or overgrowth of a part or organ, not due to tumor formation. Hypertrophy denotes greater bulk through increase in size, but not in number, of cells or other individual tissue elements.

Hypertrophic Cardiomyopathy:  A heart condition resulting in abnormal thickening of the ventricular septum and left ventricular wall.

Hypohidrosis:  Decreased ability to sweat

Hypotonia:  A condition of diminished tone of the skeletal muscles, and the reduced resistance of muscles to passive stretching; may be a symptom with several LSDs

TOP


I

Immune system:  A collection of cells and proteins that work to protect against foreign organisms or substances in the body.

Infarct:  An area of dead tissue resulting from diminished or stopped blood supply. Infarcts can occur in any type of tissue, including bone.

Informed consent:  Permission given by an individual to proceed with a specific test or procedure, with an understanding of the risks, benefits, limitations, and potential implications of the procedure itself and its results

Infusion:  The introduction of a fluid other than blood into a vein, often over a long period of time. Many medicines are administered by infusion.

Interfamilial variability:  Variability in clinical presentation of a particular disorder among affected individuals from different families

Intrafamilial variability:  Variability in clinical presentation of a particular disorder among affected individuals within the same immediate or extended family

Intravenous:  A word meaning "within a vein or veins." Used to describe an injection into a vein to provide nutrition, water, or medication. Infusions are given intravenously.

Intron:  Non-coding sequence of DNA removed from mature messenger RNA prior to translation

Isosthenuria:  A state in renal disease in which the kidney cannot concentrate or dilute urine. The specific gravity of the urine becomes fixed around 1.010, irrespective of the fluid intake.

TOP


J

 

TOP


K

Karyotype:  A photographic representation of the chromosomes of a single cell, cut and arranged in pairs based on their size and banding pattern according to a standard classification.

Kindred:  An extended family; term often used in linkage studies to refer to large families

Known family-specific mutations:  A specific disease-causing mutation identified in an affected family member; testing is recommended for other at-risk family members who might have that specific mutation; for example, if sequence analysis identifies a disease-causing mutation in an affected family member, all at-risk relatives need only to be tested for their family-specific mutation.

TOP


L

Linkage: The tendency for genes or segments of DNA closely positioned along a chromosome to segregate together at meiosis and therefore be inherited together

Linkage analysis:  (synonym: indirect DNA analysis) Testing DNA sequence polymorphisms (normal variants) that are near or within a gene of interest to track within a family the inheritance of a disease-causing mutation in a given gene

Lipid:  A type of fat molecule. Lipids are important components of cellular membranes.

Locus:  The physical site or location of a specific gene on a chromosome

Lymphedema:  Swelling of the subcutaneous tissues caused by obstruction of the lymphatic drainage.

Lyonization:  When genes on one of the x-chromosomes of the female is randomly inactivated early in the developmental process.

Lysosome:  A specialized compartment within a cell that contains enzymes for breaking down complex molecules.

Lysosomal storage disorders:  A class of genetic disorders characterized by deficiencies of specific enzymes found in lysosomes, particularly those in macrophages.

TOP


M

Macroglossia:  Enlargement of the tongue; may be a symptom with several LSDs.

Macrophage:  A type of white blood cell that actively consumes and removes foreign materials and cellular debris from the body. Some macrophages reside in connective tissue, liver, or spleen, and others circulate in the blood.

Manifesting carrier:  An individual who has, at a particular locus, a recessive, disease-causing allele on one chromosome and a normal allele on the other chromosome and who manifests some symptoms of the disorder; generally refers to female carriers of an X-linked recessive mutation who are clinically affected, although the phenotype is usually less severe as compared to males with the same mutation. Related Terms: X-chromosome inactivation; X-chromosome inactivation study; X-linked recessive; carrier; heterozygote; lyonization

Marker: An identifiable segment of DNA (e.g., RFLP, VNTR, microsatellite) with enough variation between individuals that its inheritance and co-inheritance with alleles of a given gene can be traced; used in linkage analysis

Metabolic:  Relating to metabolism, a term used to describe the chemical and physical changes that occur in the body when molecules are either broken down or built up in cells and tissues.

Missense mutation:  A single base pair substitution that results in the translation of a different amino acid at that position

Mitral Valve Insufficiency:  Malfunction of the Mitral valve, allowing the regurgitation or backflow of blood.

Mitral Valve Prolapse:  A heart valve that does not completely block the backward flow of blood. Heart valves close when the heart pumps to keep blood flowing in one direction.

Mode of inheritance:  (synonyms: inheritance pattern, pattern of inheritance) The manner in which a particular genetic trait or disorder is passed from one generation to the next. Autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, multifactorial, and mitrochondrial inheritance are examples

Molecular genetic testing:  (synonyms: DNA testing, DNA-based testing, molecular testing) Testing that involves the analysis of DNA, either through linkage analysis, sequencing, or one of several methods of mutation detection

Molecule:  The smallest particle of a substance that retains all the properties of the substance and is composed of one or more atoms.

Monocyte:  A type of white blood cell that has a single nucleus. Monocytes are usually located in the lymph nodes, spleen, bone marrow, and soft connective tissue.

Multiple myeloma:  A form of cancer that originates in the bone marrow and is associated with signs and symptoms similar to those found in Gaucher disease, such as anemia, hemorrhage, recurrent infections, and weakness.

Mutant gene:  A gene that has changed (mutated), affecting normal transmission and expression of a trait.

Mutation:  The process by which a gene or some other DNA sequence undergoes a permanent change in the structure. Mutations are gene defects where an error in the code for a specific structural or functional protein.

Mutation scanning:  A process by which a segment of DNA is screened via one of a variety of methods to identify variant gene region(s). Variant regions are further analyzed (by sequence analysis or mutation analysis) to identify the sequence alteration. Related Terms: CSGE; DGGE; DNA-based testing; PCR; SSCP; molecular genetic testing; sequence analysis; targeted mutation analysis

MRI (magnetic resonance imaging):  Medical imaging that allows a noninvasive view of the internal organs, including bone marrow. Sometimes used to aid in the monitoring of LSDs.

Mutated gene/mutation:  A gene that has changed (mutated), affecting normal transmission and expression of the trait that gene controls.

TOP


N

Neurologic:  Of or relating to the central nervous system.

Neuromuscular disorder:  A disorder involving the relationship between nerves and muscles, and especially the weakening or dysfunction of the muscles.

Neuronopathic:  A word used to describe a disorder that affects the brain or nervous system. Many LSDs have both neuronopathic and non-neuronopathic types.

Neuropathic:  The disease of the nervous system.

Neutropenia:  A lack of neutrophils (white blood cells) in the blood.

Newborn screening:  Testing done within days of birth to identify infants at increased risk for a specific genetic disorder so that treatment can begin as soon as possible; when a newborn screening result is positive, further diagnostic testing is usually required to confirm or specify the results and counseling is offered to educate the parents

Nodule:  A small knob or mass of differentiated tissue.

Nonsense mutation:  A single base pair substitution that prematurely codes for a stop in amino acid translation (stop codon)

Novel mutation:  A distinct gene alteration that has been newly discovered; not the same as a 'new' or 'de novo' mutation

Nucleotide:  A molecule consisting of a nitrogenous base (adenine, guanine, thymine, or cytosine in DNA; adenine, guanine, uracil, or cytosine in RNA), a phosphate group, and a sugar (deoxyribose in DNA; ribose in RNA). DNA and RNA are polymers of many nucleotides.

Nucleus:  The cell's "command center," containing all a person's genetic material.

TOP


O

Obligate carrier:  (synonym: obligate heterozygote) An individual who may be clinically unaffected but who must carry a gene mutation based on analysis of the family history; usually applies to disorders inherited in an autosomal recessive or X-linked recessive manner

Osteoporosis:  A reduction in bone mass that causes an increased susceptibility to fractures.

Osteochondritis:  Inflammation of the bone and its cartilage.

Osteonecrosis:  Death of bone tissue.

Osteopenia:  Loss of bone density, which may lead to osteoporosis and bone complications such as collapsed vertebrae, bone fractures, and avascular necrosis.

Organelle:  Smaller components within cells responsible for carrying out various functions of the cell (reproduction, consumption, waste disposal, etc.)

TOP


P

Pan ethnic:  Affecting people of any ethnic background. Most of the LSDs are panethnic, but some of them are more common in certain ethnic groups.

Paresthesia:  The burning, tingling painful sensation that Fabry patients experience.

Pathologic fracture:  A sudden break in a bone caused by a slow loss of bone density due to a disease.

Pathogenesis:  The underlying origin or cause of a disease.

PCR:  (synonym: polymerase chain reaction) A procedure that produces millions of copies of a short segment of DNA through repeated cycles of: 1) denaturation, 2) annealing, and 3) elongation; PCR is a very common procedure in molecular genetic testing and may be used to: 1) generate a sufficient quantity of DNA to perform a test (e.g., sequence analysis, mutation scanning), or 2) may be a test in and of itself (e.g., allele-specific amplification, trinucleotide repeat quantification).

Pedigree:  A family tree; a diagram that a genetic councilor will draw to outline the family history.

Phenotype:  The outward manifestations (e.g., eye color, disease symptoms, etc.) that result from the genotype (the genetic material), sometimes in interaction with the biologic environment.

Physical therapist:  A specialist trained in the treatment of diseases and injury through exercise and physical activities; may be involved in addressing some LSD symptoms.

Platelets:  Blood cells involved in clotting.

Point mutation:  An alteration in DNA sequence caused by a single nucleotide base change, insertion, or deletion

Polymorphism:  Natural variations in a gene, DNA sequence, protein, or chromosome that have no adverse effect on the individual and occur with fairly high frequency in the general population

Predictive testing:  Testing offered to asymptomatic individuals with a family history of a genetic disorder and a potential risk of eventually developing the disorder

Prenatal diagnosis:  (synonym: prenatal testing) Testing performed during pregnancy to determine if a fetus is affected with a particular disorder. Chorionic villus sampling (CVS), amniocentesis, periumbilical blood sampling (PUBS), ultrasound, and fetoscopy are examples of procedures used either to obtain a sample for testing or to evaluate fetal anatomy.

Presymptomatic testing: Testing of an asymptomatic individual in whom the discovery of a gene mutation indicates certain development of findings related to a specific diagnosis at some future point. A negative result excludes the diagnosis.

Proband:  (synonyms: index case, propositus) The affected individual through whom a family with a genetic disorder is ascertained; may or may not be the consultand (the individual presenting for genetic counseling)

Protein:  The building blocks of cells involved in all essential life functions (e.g., cell growth, energy production, metabolism). Enzymes are a type of protein.

Pruritus:  Itching.

Proteinuria:  Excessive protein in the urine.

Puberty:   A sequence of events by which a child becomes an adult. Characterized by the secretion of gonadal hormones and the development of secondary sexual characteristics (e.g., facial hair in males and breasts in females).

Pubertal delay:  A lack of the signs of puberty in either sex by age 14. Delayed puberty and other growth-related problems or delay can be symptoms related to many LSDs.

Pulmonary:  Relating to the lungs, to the pulmonary artery, or to the opening leading from the right ventricle of the heart into the pulmonary artery.

TOP


Q

 

TOP


R

Reading frame:  (synonym: exon) A sequence of messenger RNA that is translated into an amino acid chain, three bases at a time, each triplet sequence coding for a single amino acid

Receptors:  Specialized structures, often on the surface of cells, that recognize molecules for signaling or for transporting into the cell.

Recessive:  A genetic trait that is only expressed if both genes in the pair code for it; it can be "overridden" if the other gene in the pair codes for a dominant trait.

Recombinant DNA technology:  A procedure for manufacturing proteins by manipulation of DNA segments. Used to produce large quantities of enzymes for use in enzyme replacement therapy.

Recurrence risk:  The likelihood that a trait or disorder present in one family member will occur again in other family members in the same or subsequent generations

Red blood cell:  A cell in the blood of vertebrates that transports oxygen and carbon dioxide to and from the tissues; in mammals it contains hemoglobin.

Renal:  Of or pertaining to the kidney.

Restriction site:  A sequence of DNA that is recognized by an endonuclease (a protein that cuts DNA) as a site at which the DNA is to be cut

Ribonucleic acid (RNA):  A nucleic acid that helps transfer information from DNA to the protein-forming system of the cell.

Risk assessment:  Calculation of an individual's risk, employing appropriate mathematical equations, of having inherited a certain gene mutation, of developing a particular disorder, or of having a child with a certain disorder based upon analysis of multiple factors including family medical history and ethnic background

RNA:  (synonym: ribonucleic acid) The molecule synthesized from the DNA template; contains the sugar ribose instead of deoxyribose, which is present in DNA; three types of RNA exist, messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA)

TOP


S

Screening:  Testing designed to identify individuals in a given population who are at higher risk of having or developing a particular disorder, or having a gene mutation for a particular disorder

Sensitivity:  The frequency with which a test yields a positive result when the individual being tested is actually affected and/or has the gene mutation in question

Sepsis:  Destruction of tissue by bacterial toxins; infection.

Sequence analysis:  (synonyms: gene sequencing, sequencing) Process by which the nucleotide sequence is determined for a segment of DNA

Sequence alteration:  (synonym: mutation) Any alteration in a gene from its natural state; may be benign (commonly referred to as a "polymorphism"), pathogenic, or of unknown significance

Slit Lamp Ophthalmoscop:  Examination of the eye with an instrument consisting essentially of a mirror that reflects light into the eye and a central hole through which the eye is examined. It is a simple exam that can be performed by most eye doctors (ophthalmologists).

Small molecule drugs:  Form of LSD treatment that attempts to use small molecules to administer therapies to stabilize faulty enzymes or minimize the amount of waste material that accumulates.

Specificity:  The frequency with which a test yields a negative result when the individual being tested is actually unaffected and/or does not have the gene mutation in question

Splenomegaly:  Enlargement of the spleen; may be a symptom with several LSDs.

Splenectomy: Surgical removal of the spleen.

Splicing:  (synonym: splicing mutation) The process by which introns, non-coding regions, are excised out of the primary messenger RNA transcript and exons (i.e., coding regions) are joined together to generate mature messenger RNA

Sporadic: The chance occurrence of a disorder or abnormality that is not likely to recur in a family

Substrate:  Waste material that may accumulate in cell lysosomes when it is not broken down by enzymes.

Symptom management: Care for LSD patients that tries to alleviate and manage their symptoms with a variety of methods (surgery, drugs, dialysis, transplantation, etc.), but does not affect the underlying cause of the disease. (Synonym for palliative or supportive care.)

TOP


T

Thalassemia:  An inherited blood disorder affecting the production of hemoglobin.

Thrombocytopenia:  A condition in which there is an abnormally small number of platelets in the blood.

Tortuosity:  A twisted or crooked.

Transcription: The process of synthesizing messenger RNA (mRNA) from DNA

Translation: The process of synthesizing an amino acid sequence (protein product) from the messenger RNA code

Type 1 Gaucher disease (non-neuronopathic):  A form of Gaucher disease that involves primarily the spleen, liver, blood and bone. Type 1 Gaucher disease does not involve the nervous system. Signs include anemia, low platelet count, enlarged spleen and/or liver, and bone problems.

Type 3 Gaucher disease (chronic neuronopathic):  A rare form of Gaucher disease that involves the nervous system in addition to other organs and tissues. Neurologic signs and symptoms are less severe than those seen in Type 2 Gaucher disease

TOP


U

Unaffected:  An individual who does not manifest any symptoms of a particular condition

Urticaria:  An eruption of itchy hives on the skin.

TOP


V

Variable expressivity:  Variation in clinical features (type and severity) of a genetic disorder between affected individuals, even within the same family

TOP


W

White blood cells:  A group of cells that are involved in protecting the body from infection and invasive foreign materials.

White Matter Infarcts:  Small deep infracts either in the cerebral hemisphere or in the brainstem.

Whorling:  A starburst pattern commonly found on the cornea of people with Fabry disease.

Wild-type allele: The normal, as opposed to the mutant, gene or allele

TOP


X

X-chromosome:  Sex determining chromosome. Females have two X Chromosomes.

X-chromosome inactivation:  (synonym: lyonization) In females, the phenomenon by which one X chromosome (either maternally or paternally derived) is randomly inactivated in early embryonic cells, with fixed inactivation in all descendant cells; first described by the geneticist Mary Lyon

X-linked:  A genetic disease whereby the faulty gene is carried on the X chromosome.

X-linked recessive disorder:  A genetic disease caused by a gene mutation on an X chromosome (one of the chromosome that determines a person's gender), caused when a male inherits the mutated gene from his father or (more rarely) when a woman inherits it from both parents.

X-ray:  Electromagnetic radiation of short wavelength used to penetrate tissues and record densities on film. Sometimes used to aid in diagnosis of LSDs.

TOP


Y

Y-chromosome:  Sex determining chromosome. Males have one X and one Y chromosome.

TOP


Z

 

TOP