SPINAL MUSCULAR ATROPHY TYPE 1

\n\nSMA 1 is a progressive muscle disease which is caused by a genetic defect transmitted as Autosomal Recessive with incidence of about 1 in 10,000 births. Boys are slightly more affected than girls.\n\nDue to genetic defect in SMN 1 ( spinal motor neuron ) there is no signal from spinal cord to nerves hence wasting of muscles.\n\nIf untreated, it leads to death with respiratory failure.\n\n Symptoms \n

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• Floppy baby. No reflexes in extremities.
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• Muscle weakness which is progressive.
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• Difficulty achieving developmental milestones, difficulty sitting/standing/ walking.
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• In small children: adopting of a frog-leg position when sitting (hips abducted and knees flexed).
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• Loss of strength of breathing muscles.
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• Weak cry , cannot suck or eat well.
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• Tongue twitching or fasiculations.
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\nCause \n\nGenetic defect at Chromosome 5q13 area which is inherited as Autosomal Recessive\n\nDiagnosis \n\nThe most severe manifestation on the SMA spectrum can be noticeable to mothers late in their pregnancy by reduced or absent fetal movements. Symptoms are critical (including respiratory distress poor feeding) which usually result in death within weeks, in contrast to the mildest phenotype of SMA (adult-onset), where muscle weakness may present after decades and progress to the use of a wheelchair but life expectancy is unchanged.\n\nThe more common clinical manifestations of the SMA spectrum that prompt diagnostic genetic testing:\n\nProgressive bilateral muscle weakness (Usually upper arms & legs more so than hands and feet).\n\n\n\nFlattening of the chest wall when taking a breath and belly protrusion when taking a breath in.\n\nNo Reflexes \n\nEMG Electromyogram shows poor signals from spinal cord to muscles.\n\nWhile the above symptoms point towards SMA, the diagnosis can only be confirmed with absolute certainty by blood test to check chromosome defect (Genetic Testing), it takes about 2 months to get this report.\n\n Management \n\nIn past only supportive treatment was provided, most children did not survive past their second birthday. CPAP / BIPAP ventilation G Tube feeding. Nutritional Support Few years ago Spirnaza was found to decrease progression of muscle atrophy It is given intrathecal ( in spinal cord area).\n\nFirst dose is about $ 800,000 then every 4 months dose is about $ 350,000 Last year Gene therapy came in to light in America. The medicine is called Zolgensma which is a one time dose given by Intravenous route. The cost is about $ 2.8 Million CAD. So far, it is sill not available in Canada. Parents do fund raising for this treatment currently.\n\nAlthough only a few children have been through this treatment, the results are beneficial.\n\nA lot of children did not need ventilation support. It works best if given as early as possible. It does not have benefit after age 2.\n\n