| Glossary of Terms That May Appear in Literature About
Prader-Willi Syndrome.
 |
| 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 |
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| Adrenarche |
Onset of pubic and axillary hair;
normally occurs after age 8 years. |
| Adrenal glands |
Glands that sit on top of the
kidneys and regulate stress reactions and some mineral balance. |
| Adrenocorticotropic
hormone (ACTH): |
A hormone secreted by the
pituitary that stimulates the adrenal glands; part of the stress response system. |
| Allele |
One of two or more alternative forms of a gene
occupying corresponding sites (loci) on partner chromosomes. |
| Amenorrhea |
Lack of menstrual periods. |
| Amniocentesis |
A procedure in which a small amount of the
amniotic fluid surrounding the fetus is drawn off and subjected to genetic and biochemical
analysis. |
| Androgen |
Any one of several male hormones. |
| Angelman syndrome |
A rare syndrome reported in 1965 by Dr. H.
Angelman and associated with a chromosome 15 deletion similar to that seen in PWS. In AS,
however, the deletion is seen on the chromosome contributed by the mother, whereas those
with PWS lack certain genes from the father. The clinical problems and appearance of AS
and PWS are distinctly different. These two syndromes represent the first examples in
humans of genetic imprinting. |
| Autosome |
Any chromosome that is not a sex chromosome; in
humans there are 22 pairs of autosomes and one pair of sex chromosomes. |
| Chromosome |
Package of genes that carries genetic
information. Most cells have 46 chromosomes, which are found in the nucleus. |
| Chromosome abnormality |
Any variation from the normal
chromosomal pattern. The common abnormalities found in Prader-Willi syndrome are:
- Deletion: a condition in which a piece of
genetic material is lost or missing from a chromosome. Typically it is a small piece
of the long arm of the 15th chromosome that is missing.
- Translocation: a transfer of a fragment of one
chromosome to another chromosome.
|
| Cocontraction |
The simultaneous contraction of
all the muscles around a joint to stabilize it. |
| Cortisol |
A hormone secreted by the adrenal
glands in response to stress. |
| Cryptorchidism |
Undescended testicles (testicles are not
present in the scrotal sac). |
| DNA |
Deoxyribonucleic acid; the genetic code or
chemical blueprint for the cell. |
| de novo |
New. Used in genetics to describe a structural
alteration of the chromosomes that is present in a child but not in either parent. |
| Deletion |
A missing piece of chromosomal material.
In PWS, the deletion is in the proximal long arm of chromosome 15. |
| Dominant |
Capable of expression when carried by only one
of a pair of partner chromosomes in the cells of the body. |
| Down syndrome |
A syndrome resulting from three (instead of the
usual two) copies of chromosome 21. |
| Dual-photon
absorptiometry (DPA) |
A gamma radiation technique for
measuring bone density. |
| Electrophoresis |
In genetics, the technique for separating
materials via the movement of
charged particles suspended in a gel under the influence of an applied electric field. |
| Failure
to thrive |
Poor or inadequate weight gain during infancy. |
| FISH |
Fluorescence in situ hybridization.
A test using a fluorescence-tagged segment of DNA that combines with the DNA
present in the normal PWS critical region and allows determination by its presence or
absence as to whether a 15q deletion is present. |
| Gene |
A unit of genetic information. Usually
contains the genetic code for one protein. |
| Genetic imprinting |
Differential modification of the expression of genes depending upon
whether they are inherited from the mother or the father. This affects only certain
segments of the human genetic complement, including PWS and Angelman syndrome on
chromosome 15q. |
| Genetic counseling |
Counseling that explains facts about genetics issues to parents/care
providers. Emphasis is on clarification of information, possible recurrence risk,
reproductive options, support to affected persons and their families, and follow-up
services. |
| Glucocorticoid |
Hormones secreted by the adrenal glands regulating sugar and energy
availability. |
| Gonadotropin |
A hormone from the pituitary gland that stimulates the genital organs to
produce the sex hormones. |
| Growth hormone (GH) |
A pituitary-secreted hormone that aids in growth. |
| Gynecomastia |
Breast development -- used in reference to male breast development. |
| Heredity |
The genetic transmission or passing of a
particular quality or trait from parent to offspring. |
| Hyperphagia |
Consumption of more than a normal quantity of
food. |
| Hypogenitalism |
The genital organs are undersized. |
| Hypogonadism |
A condition of abnormal decrease in the
function of the ovaries and testes, causing retardation of growth and sexual development. |
| Hypogonadotropic
hypogonadism |
Hypogonadism resulting from a
decrease in hormones released by the pituitary. |
| Hypopigmentation |
Unusually lighter hair, eyes, and skin color in
relation to other family members. This decreased pigmentation is common in PWS,
particularly in individuals with partial deletion of the long arm of chromosome 15. |
| Hypothalamus |
The part of the brain that controls appetite,
body temperature, hormones, and other vital functions. |
| Hypotonia |
Decreased muscle tone. Decreased muscle
resistance to passive movement. |
| IGFBP-3 |
A binding protein for insulin-like growth
factor (IGF) that carries it around the blood stream. |
| Imprinting center |
The portion of a chromosome that controls whether imprinted
genes on that chromosome are expressed. If the imprinting center is missing or altered,
genes that require imprinting will not function appropriately. |
| Insulin |
A hormone secreted by the pancreas that
regulates sugar in the body. |
| Insulin-like growth
factor I and II (IGF-I, IGF-II) |
Factors that act upon body tissues
to stimulate growth. |
| Karyotype |
The collection of chromosomes from the nucleus
of a cell arranged according to established guidelines; the photomicrograph of
chromosomes. |
| Klinefelter's syndrome |
XXY syndrome. A chromosome abnormality in
which a male has an extra X chromosome. |
| Lability |
Marked fluctuations in mood or disposition. |
| Learning disabled |
A term applied to low-achieving children whose
performance is inconsistent with overall intelligence. These children may be part of
an identifiable group who are limited in their ability to process written or spoken
language, which may result in limited capacity to master some basic academic tasks. |
| Loci |
Sites on chromosomes occupied by genes. |
| Luteinizing hormone (LH) |
One of the pituitary hormones
acting upon the genital organs. |
| Maternal |
Referring to the mother. |
| Melatonin |
A hormone secreted by the pineal gland in the
brain. |
| Mental age |
A measured level of cognitive function
established by a test of intelligence. |
| Metabolism |
Pertaining to the body's process of absorbing
nourishment from food and turning it into energy or stored fat. |
| Methylation |
DNA methylation analysis. A form of genetic testing used to
determine the parent of origin of chromosome 15q, which is always maternal in Prader-Willi
syndrome. |
| Motor planning |
The ability of the brain to conceive of,
organize, and carry out a sequence of unfamiliar activities. Also known as
"praxis." |
| Mutation |
A sudden change in the genetic material that
can be passed to an offspring. |
| Narrow
bifrontal diameter |
A narrow forehead. |
| Normalization |
The effort to make available activities and
patterns of everyday life that are as close as possible to the habits of normal,
mainstream individuals. |
| Obesity |
A condition in which body weight is
considerably (more than two standard deviations) above the range that is normal for body
height. |
| Orchiopexy |
Surgical lowering of the testicles into the
scrotum. |
| Osteoporosis |
Demineralization (thinning) of the bones. |
| Oxandrolone |
An anabolic (mass-building) steroid. |
| Paternal |
Referring to the father. |
| Pedigree |
Diagram showing family members, their
relationships, and presence or absence of a particular trait or traits. |
| Phenotype |
The clinical expression; often used when
talking about a genetic condition. |
| Pituitary |
A gland at the base of the brain, stimulated by
a portion of the brain called the hypothalamus, that secretes hormones that work elsewhere
in the body (e.g., ACTH, FSH, LH, TSH, prolactin). |
Polymerase chain
reaction
(PCR) |
A genetic laboratory technique used to copy and
amplify a portion of a gene or DNA sequence (for example, SNRPN gene). The sizes or
alterations of the PCR amplified portion of the gene identified may be useful in
diagnosing certain genetic conditions. |
| Polymorphism |
Normal variation in genetic information.
Used to describe minor variation in chromosome shape and normal or abnormal variation in
molecular structure or content of genes. |
| Praxis |
The capacity of the brain to integrate and
carry out unfamiliar motor activities. Also known as motor planning. |
| Prolactin |
A pituitary-secreted hormone acting upon the
genital organs and breasts. |
| Proximal musculature |
The muscles of the trunk, shoulder girdle, and
hip girdle. |
| Rehabilitation |
A dynamic process of continuing evaluation of
disabled individuals in order to meet their need and develop realistic methods of coping.
This "process" acknowledges that one individual may have more than just
one problem to confront and that the individual's ability to function cannot be separated
from environmental concerns. |
| Restriction endonuclease |
An enzyme-produced bacteria which cleaves or
cuts DNA into fragments at specific sites. |
| Sheltered
workshop |
A controlled work-oriented rehabilitation
setting that utilizes work experiences and related services to assist disabled individuals
in making the maximum progress possible toward vocational productivity and normal living. |
| Southern blotting |
The process of transferring DNA fragments
from the electrophoresis gel onto filter paper; named after Dr. E. Southern. |
| Strabismus |
A lack of coordinated eye muscle movement,
observed as either "crossed-eye" or "wall eye." |
| Syndrome |
A term used to describe a symptom complex
characterized by many medical signs. In many syndromes, not all affected individuals
will have every diagnostic sign. |
| System advocacy |
Refers to actions taken by individuals or
groups to influence policy making. |
| Tanner
stages |
A five-step staging of pubertal development:
1 = prepuberty; 5 = full adult breast (females), pubic hair, or genital development. |
| Thyroid-releasing
hormone (TRH) |
A hypothalamic hormone that
stimulates the release of TSH from the pitutary. |
| Thyroid-stimulating
hormone (TSH) |
A pituitary hormone that
stimulates the thyroid, leading to increases in metabolism and heart rate. |
| Turner syndrome |
A syndrome with only one sex chromosome (XO)
but phenotypical appearance of a female. |
| Uniparental
disomy |
A situation in which both members of a
chromosome pair are derived from a single parent. In about one-fourth of people with
PWS, both chromosome 15s are maternal in origin, and no paternal chromosome 15 is present
in the affected individual. |
| X-linked |
Genes on the X chromosome or traits
determined by such genes. |
edited:
02/21/2008