X-linked Recessive Disorders Flashcards
Are female carriers of X-linked recessive alleles affected by disease?
Female carriers can be variably affected depending on the percent inactivation of the X chromosome carrying the mutant vs. normal gene.
Duchenne muscular dystrophy is typically due to…
Frameshift mutations that lead to production of truncated dystrophin protein and skeletal muscle fragility
Muscle weakness in Duchenne muscular dystrophy typically begins in…
Pelvic girdle muscles and progresses superiorly.
In DMD, pseudohypertrophy of calf muscles is due to…
Fibrofatty replacement of muscle
Describe the Gower maneuver.
Pts use upper extremities to help them stand up.
A common cause of death in DMD is…
Dilated cardiomyopathy
Onset of symptoms in DMD occurs…
Before 5 years of age
What is the normal function of dystrophin?
It connects the intracellular cytoskeleton (actin) to the transmembrane proteins alpha- and beta-dystroglycan, which are connected to the extracellular matrix.
Loss of dystrophin function results in…
Myonecrosis
Which biochemical abnormalities are seen in patients with DMD?
Increased CPK and aldolase levels in serum
How is a diagnosis of DMD made?
Western blot and muscle biopsy
Becker muscular dystrophy is an X-linked recessive disorder typically due to…
Non-frameshift insertions in the dystrophin gene. The result is production of partially functional dystrophin rather than a truncated, non-functional version of the protein. Consequently, BMD is less severe than Duchenne.
Onset of Becker muscular dystrophy symptoms is typically in…
Adolescence or early adulthood.
Be Wise, Fool’s GOLD Heeds silly HOpe.
- Bruton agammaglobulinemia
- Wicket-Aldrich syndrome
- Fabry disease
- G6PD deficiency
- Ocular albinism
- Lesch-Nyhan syndrome
- Duchenne (and Becker) muscular dystrophy
- Hunter syndrome
- Hemophilia A and B
- Ornithine transcarbamylase deficiency
