Limb-girdle muscular dystrophy 2J, Titin gene mutation (Q86066)

Limb-girdle muscular dystrophy type 2J (LGMD2J) is caused by homozygous mutation in the titin gene, whereas heterozygous mutation in the titin gene causes tardive tibial muscular dystrophy. Mutation in the titin gene also causes dilated cardiomyopathy type 1G. Onset of the severe phenotype is in the first to third decades and involves weakness of all proximal muscles. Severe disability with loss of ambulation occurs within 20 years (third to sixth decades). There is no facial muscle involvement or cardiomyopathy. Some patients later develop distal muscle involvement.