Charcot-Marie-Tooth Disease Type 4C and Autosomal Dominant Heterozygous Ichthyosis Vulgaris, with Bilateral Hearing Loss: A Novel Association with Review of Literature.

A 3-year-old boy, firstborn to nonconsanguineous parents, presented with motor development delay and floppiness of bilateral lower limbs since birth. No significant family history presented at time of check-up. He could stand with support, eat with a spoon without spillage, and speak in two-word sentences. There was no history suggestive of cranial nerve impairment. Examination revealed normal head circumference, dry, scaly skin lesions on the trunk, distal weakness with sluggish deep tendon reflexes in bilateral lower limbs, and a high stepping gait. Nerve conduction studies revealed demyelinating polyneuropathy. Brain stem-evoked response audiometry testing revealed auditory neuropathy. Clinical exome sequencing revealed a known pathogenic variant of 3325C > T in the SH3TC2 gene suggestive of Charcot-Marie-Tooth disease type 4C and ichthyosis vulgaris with a novel variant of 2218C > T in the FLG gene. We have reviewed the available literature for reported associations of Charcot-Marie-Tooth disease type 4C and ichthyosis vulgaris. This is probably the first reported association of Charcot-Marie-Tooth disease type 4C and ichthyosis vulgaris with bilateral hearing loss.