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Glucose-6-phosphate dehydrogenase
(G6PD)
An enzyme that
helps to protect red blood cells from being destroyed (hemolytic anemia)
when a person is exposed to certain foods, drugs, or the stress of
infection. G6PD deficiency is the most common inherited human enzyme
disorder, and is especially common in African-American males, and persons
of Mediterranean, Middle Eastern, and Asian origin. The most severe cases
of G6PD deficiency appear to occur in Asian and Mediterranean populations
The condition is transmitted by mutations in the G6PD gene located on the X
chromosome and follows an X-linked recessive inheritance (sex-linked)
pattern
The normal random inactivation of one of the two X chromosomes that
occurs in females can lead to a partial deficiency in female carriers which may
not be detected using screening tests. Carrier detection using prenatal DNA
analysis to detect specific mutations may be more suitable in patients with
high risk for severe enzyme deficiency. Sequencing of the G6PD gene
is available from
Emory Genetics Laboratory
SEE ALSO:OMIM
Gastroschisis
An opening beside the umbilical cord that allows bowel to protrude outside of
the abdomen. Gastroschisis is thought to arise from disruption
of blood flow to the affected abdominal wall.
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Gene
A section of the molecule DNA (deoxyribonucleic acid) which codes for a particular protein and carries the hereditary information for such
characteristics as hair color, eye color, and susceptibility to disease.
Genetic counseling
Evaluation of prospective parents' risks of having a child born with a birth defect
or genetic disorder, and advise on
their
options for testing and treatment.
Gestational age
Time elapsed since the first day of the last menstrual period. If pregnancy was achieved using assisted reproductive
technology, gestational age is calculated by adding 2
weeks to the conceptional age.
Gestational diabetes (GDM)
Carbohydrate intolerance with onset or first
recognition during pregnancy.
A fasting plasma glucose level >126 mg/dl (7.0
mmol/l) or a casual plasma glucose >200 mg/dl (11.1 mmol/l) meets the threshold
for the diagnosis of diabetes, if confirmed on a subsequent day, and precludes
the need for any glucose challenge. In the absence of this degree of
hyperglycemia patients may be evaluated using a 1 hour 50 gram oral glucose
tolerance test (OGTT) as screening test, or proceed directly to a diagnostic 3 hour 100
gram OGTT . Gestational diabetes increases the risk of maternal hypertensive
disorders, cesarean delivery, fetal macrosomia, neonatal hypoglycemia, jaundice,
polycythemia, and hypocalcemia. In addition, fasting hyperglycemia may be associated with an
increase in the risk of intrauterine fetal death during the last 4–8 weeks of
gestation .
Goodell's sign
Softening of the cervix seen as early as probable sign of pregnancy. Goodell's
sign may be observed as early as six weeks of pregnancy.
Gravida
A pregnant woman.
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