Familial monomelic amyotrophy: a case report from India.

Monomelic amyotrophy (MMA) is a benign lower motor neuron disorder in the young with male preponderance. It is characterized by insidious onset and progressive weakness and wasting of a distal extremity over a few years followed by spontaneous arrest. The exact pathogenesis is unknown. It is predominantly a sporadic disorder but rarely familial forms have been documented. In this report, we describe the phenotype of a 21-year-old man and his mother who were diagnosed to have MMA. The index case presented with left upper limb weakness and wasting of 3 years duration while his mother had right upper limb amyotrophy and weakness of 34 years. A total of 190 patients were diagnosed to have MMA in our institute over the last 27 years and this is the first case of familial MMA.