‘Distal 16p12.2 microdeletion’ in a patient with autosomal recessive deafness-22
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The 16p12.2 chromosome band contains three large segmental duplications: BP1, BP2 and BP3, providing a substrate for recombination and recurrent chromosomal rearrangements. The ‘16p12.2 microdeletion’ is a recurrent deletion comprised between BP2 and BP3, associated with variable clinical findings. We identified a heterozygous 16p12.2 microdeletion spanning between BP1 and BP2 in a child evaluated for short stature and mild dyslexia. Unexpectedly, the mother carried the same deletion in the homozygous state and suffered from severe hearing loss. Detailed family history revealed consanguinity of the maternal grandparents. The 16p12.2 microdeletion is a rare condition and contains only three genes: METTL9, IGSF6 and OTOA of which the OTOA is considered responsible for DFNB22 hearing loss (MIM: 607039) under its homozygous condition. A number of OTOA mutations have been described, whereas very few cases of a 16p12.2 microdeletion similar to that observed in our family have been reported. In conclusion, we describe a rare ‘distal 16p12.2 microdeletion’ widening the phenotypic spectrum associated with the recurrent 16p12.2 microdeletion and support the causative role of OTOA microdeletion in hearing impairment.
Keywordssegmental duplications chromosomal rearrangements hearing loss OTOA gene
We thank the parents for their kind participation and support. We are grateful to Marco Bertorello and CorradoTorello for their technical assistance. This work was supported by ‘Cinque per mille dell’IRPEF-Finanziamento della ricerca sanitaria’ and ‘Finanziamento Ricerca Corrente, Ministero Salute (contributo per la ricerca intramurale)’.
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