Background: We report on a 6-year-old Turkish boy with profound sensorineural deafness, balance disorder, severe\r\ndisorder of oral motor function, and mild developmental delay. Further findings included scaphocephaly,\r\nplagiocephaly, long palpebral fissures, high narrow palate, low-set posteriorly rotated ears, torticollis, hypoplastic\r\ngenitalia and faulty foot posture. Parents were consanguineous.\r\nMethods and results: Computed tomography and magnetic resonance imaging showed bilateral single widened\r\ncochlear turn, narrowing of the internal auditory canal, and bilateral truncation of the vestibulo-cochlear nerve.\r\nMicroarray analysis and next generation sequencing showed a homozygous deletion of chromosome 5q31.1\r\nspanning 115.3 kb and including three genes: NEUROG1 (encoding neurogenin 1), DCNP1 (dendritic cell nuclear\r\nprotein 1, C5ORF20) and TIFAB (TIFA-related protein). The inability to chew and swallow, deafness and balance\r\ndisorder represented congenital palsies of cranial nerves V (trigeminal nerve) and VIII (vestibulo-cochlear nerve) and\r\nthus a congenital cranial dysinnervation disorder.\r\nConclusions: Based on reported phenotypes of neurog1 null mutant mice and other vertebrates, we strongly\r\npropose NEUROG1 as the causative gene in this boy. The human NEUROG1 resides within the DFNB60 locus for\r\nnon-syndromic autosomal recessive deafness on chromosome 5q22-q31, but linkage data have excluded it from\r\nbeing causative in the DFNB60 patients. Given its large size (35 Mb, >100 genes), the 5q22-q31 area could harbor\r\nmore than one deafness gene. We propose NEUROG1 as a new gene for syndromic autosomal recessive hearing\r\nloss and congenital cranial dysinnervation disorder including cranial nerves V and VIII.
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