Charcot-Marie-Tooth disease type 4D (CMT4D) is an autosomal recessive disorder of the peripheral nervous system characterized by early-onset distal muscle weakness and atrophy, foot deformities, and sensory loss affecting all modalities. Affected individuals develop deafness by the third decade of life (summary by Okamoto et al., 2014). For a phenotypic description and a discussion of genetic heterogeneity of autosomal recessive Charcot-Marie-Tooth disease, see CMT4A (214400).

X-linked syndromic intellectual developmental disorder-33 (MRXS33) is an X-linked recessive neurodevelopmental disorder characterized by delayed psychomotor development, intellectual disability, and characteristic facial features (summary by O'Rawe et al., 2015).