<prompt> Gene for myotonic dystrophy is coded on chromosome number :19202124  <response>: Answer is A Chromosome 19 : 359. The disorder is transmitted by a mutation in an unstable trinucleotide repeat sequence in a gene at 19q 133. Myotonia Dystrophica : It is the most common adult muscular dystrophy.Q Myotonic dystrophy is an autosomal dominant disorder. Q The disorder is transmitted by a mutation in an unstable trinucleotide repeat sequence in a gene at 19q 133 Muscle atrophy selectively involves type I fibres only. Q in 50 of cases Myopathy in Myotonia is unique in the sense that it is typically distal in contrast to other myopathies which are mostly proximal. Q Myotonia usually appears by the age of 5 years Q,and causes a slow relaxation of hand grip following a forced voluntary closure. 