LAUSR

We present a case of two siblings born to nonconsanguineous parents that presented with hypotonia, respiratory insufficiency, and auditory neuropathy spectrum disorder (ANSD) correlated with NFASC (MIM: 609145) and the homozygous loss of function variant p.P924RfsX35. This appears to be the first two reported cases of NFASC correlated with ANSD. NFASC encodes for neurofascin which plays an important role in the formation, function and maintenance of axon initial segments and nodes of Ranvier. Due to the rarity of this gene variation, reports are sparse in the literature leading to delays in diagnosis which can impact patient's language acquisition and spoken language skills.