Spinal muscular atrophy (SMA).

? Multiple Choice Questions Section The Neuroscience Journal introduces this new section on multiple choice questions as part of its commitment to continuous education and learning in Neurosciences. Experts in various neuroscience specialties are invited to participate with their knowledge and expertise in this section. Neurology, neurosurgery, and other board residents are encouraged to read this section to improve their knowledge and direct their reading for written examinations. Choose the most appropriate single answer. 1. Regarding spinal muscular atrophy, all are true except: a. SMA is transmitted by an autosomal recessive gene. b. The incidence is around 1 in 6000 to 10,000 live births. c. In spinal muscular atrophy type 1, mortality reaches up to 40%. d. Caused by mutation in the survival motor neuron gene (SMN1). e. In some families, SMA types 1 and 2, or types 2 and 3, can coexist. 2. In SMA type 1, all are true except: a. Movement is decreased in proximal muscles more than distal muscles b. There is often a narrowed thorax, wasted intercostals muscles (bell-shaped chest) c. Tongue fasciculations are commonly observed. d. Urinary sphincter tone and sensation is usually lost. e. Deep tendon reflexes are absent. 3. SMA with respiratory distress (SMARD 1): a. Is linked to chromosome 5q11.2-13. b. Patients have more proximal weakness than distal. c. Autonomic innervations and urinary sphincter tone are preserved. d. Never present after the first year of life. e. Characterized by early diaphragmatic involvement and respiratory distress. 4. Which one of the following is not correctly matched with the diagnostic workup: a. Blood DNA analysis→mutation of SMN gene, exon 7 & 8 deletion. b. EMG→Fibrillation potentials. c. Serum muscle enzymes→High (thousands). d. Muscle biopsy→denervation atrophy. e. Nerve conduction study→can be normal. 5. Regarding SMA types, all are true except: a. Mortality in SMA I is more than 90% in the first 2 years. b. Onset of weakness in SMA I is usually before the age of 6 months. c. SMA II patients are mainly non sitters. d. Onset of weakness in SMA III is usually after 18 months of age. e. Most patients with SMA III are walkers.