Presentation Information
[PE4-9]MTTS 1 gene variant in 7 families with syndromic and non-syndromic hearing loss
○Shujiro Minami1,2, Amina Kida1, Satomi Inoue2,3, Kiyomitsu Nara2, Hideki Mutai2, Kazuki Yamazawa3, Tatsuo Matsunaga2,3 (1.Department of Otolaryngology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan, 2.Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan, 3.Medical Genetics Center, National Hospital Organization Tokyo Medical Center, Tokyo, Japan)
The mt-tRNA Ser (UCN) (MTTS1) gene m.7471dupC variant is accompanied by symptoms of sensorineural hearing loss (SNHL) only, and ataxia, myoclonus, and intellectual disability in addition to SNHL.Family(F)1: Proband is 11- year-old girl, passed the newborn hearing screening (NHS), and diagnosed as non-syndromic moderate SNHL before school age. She had homoplasmic m.7471dupC variant from leukocytes of the peripheral blood.F2: 3-year-old boy, passed the NHS, diagnosed as severe SNHS at the age of 3. He had homoplasmic m.7471dupC variant.F3: 1-year-old boy, did not pass the NHS. The ABRs were absent at 100 dB, but the OAEs were present, and the behavioral audiological assessment indicated moderate SNHL. He showed delayed motor development, and cochlear nerve deficiency. He had heteroplasmic 58% m.7471dupC variant from leukocytes of the peripheral blood and 52.3% from the muscle.F4: 2-year-old girl, passed the NHS, and she was diagnosed as profound SNHS at the age of 2. She had homoplasmic m.7471dupC variant.F5: 6-year-old boy, passed the NHS, and he was diagnosed as mild SNHS at the age of 3. He had homoplasmic m.1555A＞G and heteroplasmic 2.2% m.7471dupC variant.F6: 37-year-old male, diagnosed as mild non-syndromic SNHL before school age and has progressed to moderate. He had homoplasmic m.7471dupC variant.F7: 2-year-old girl, did not take the NHS, diagnosed as profound SNHL at the age of 1. She had compound heterozygous CDH23 and heteroplasmic 15.9% m.7471dupC variants.Attention is required because some of the m.7471dupC mutations show good OAE responses and pass the NHS.