4. CMT Type 4 (CMT4): The Autosomal Recessive Variant
CMT4 is unique in the CMT spectrum due to its autosomal recessive inheritance pattern. Both parents must be carriers of the mutated gene, giving their child a 25% chance of developing CMT4. This form involves multiple genes and thus has several subtypes (CMT4A to CMT4J), each associated with a specific gene mutation.
CMT4 symptoms usually emerge in early childhood. Affected children might display foot deformities, muscle atrophy, and sensory loss, quite similar to CMT1. However, CMT4 has its own set of challenges, with some subtypes causing additional issues like vocal cord paralysis or slow eye movements.
Its genetic inheritance pattern aside, CMT4 is marked by its slow progression. Many affected individuals maintain ambulatory capabilities into adulthood. However, given its genetic nature, there’s a higher incidence in populations with high rates of consanguinity. (4)
