CMT is an inherited neurological disease characterized by the gradual degeneration of nerves which starts in the hands and feet and results in progressive numbness, muscle weakness and loss of function. Type 1B is inherited as an autosomal dominant pattern and involves a defect in the MPZ gene on chromosome 1. The severity of the condition is variable depending on the age of onset with severe infantile cases resulting in the inability to walk at an early age. See also Charcot-Marie-Tooth disease, Type 1B