Mehl. PED general bullet raumenu igimtos

Question 1

3M + large calves + uses arms in order to crawl up off the floor; mechanism for disorder?

Answer 1

answer = defective cystoskeletal connection to extracellular matrix

Dx = Duchenne muscular dystrophy (XR); caused by frameshift mutation; Becker is less severe form presenting in adolescence or early- adulthood; Becker not caused by frameshift (i.e., missense, etc.).

Question 2

4F + intermittent cramping past several months + difficulty relaxing grip when squeezing physician’s fingers; Dx?

Answer 2

answer = myotonic dystrophy -> CTG trinucleotide repeat (TNR) expansion.

Question 3

13M + 3-month Hx of decreasing muscle coordination + impaired speech + high-arched feet; Dx?

Answer 3

answer = Friedreich ataxia

GAA TNR expansion; development of cardiomyopathy in >90%; pes cavus (high-arched feet) a classic finding; in contrast, pes planus (flat feet) is Marfan syndrome.

Question 4

14F + tripping and incoordination past 10 months + high-arched feet + hammer toes + weakness and wasting of hand and foot muscles + deep tendon reflexes absent at ankles + vibration and proprioception decreased on lower extremities + motor nerve conduction studies decreased in lower extremities with prolonged distal motor latencies; Dx?

Answer 4

answer = Charcot-Marie-Tooth disease (aka hereditary motor and sensory neuropathy); mechanism is defective protein production for myelin sheaths and nerve fibers; hammer toes classic; pes cavus also seen.

Question 5

2M + “scissoring” of the legs + increased tone in all extremities; Dx?

Answer 5

Cerebral palsy; posited to have peripartum fetal hypoxia as precipitating cause; spastic cerebral palsy accounts for 708-80% of cases.