Noriko Morimoto1, Hideki Mutai2, Kazunori Namba2, Hiroki Kaneko3, Rika Kosaki4, Tatsuo Matsunaga5. 1. Division of Otolaryngology, National Center for Child Health and Development, 2-10-1 Ohkura, Setagaya, Tokyo 157-8535, Japan. 2. Division of Hearing and Balance Research, National Institute of Sensory Organ, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan. 3. The Institute of Natural Sciences, College of Humanities and Sciences, Nihon University, 3-25-40 Sakurajosui, Segataya, Tokyo 156-8550, Japan. 4. Division of Medical Genetics, National Center for Child Health and Development, 2-10-1 Ohkura, Setagaya, Tokyo 157-8535, Japan. 5. Division of Hearing and Balance Research, National Institute of Sensory Organ, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan; Medical Genetics Center, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan. Electronic address: matsunagatatsuo@kankakuki.go.jp.
Abstract
OBJECTIVE: To examine and expand the genetic spectrum of Waardenburg syndrome type 1 (WS1). METHODS: Clinical features related to Waardenburg syndrome (WS) were examined in a five-year old patient. Mutation analysis of genes related to WS was performed in the proband and her parents. Molecular modeling of EDNRB and the p.R319W mutant was conducted to predict the pathogenicity of the mutation. RESULTS: The proband showed sensorineural hearing loss, heterochromia iridis, and dystopia canthorum, fulfilling the clinical criteria of WS1. Genetic analyses revealed that the proband had no mutation in PAX3 which has been known as the cause of WS1, but had a homozygous missense mutation (p.R319W) in endothelin receptor type B (EDNRB) gene. The asymptomatic parents had the mutation in a heterozygote state. This mutation has been previously reported in a heterozygous state in a patient with Hirschsprung's disease unaccompanied by WS, but the patient and her parents did not show any symptoms in gastrointestinal tract. Molecular modeling of EDNRB with the p.R319W mutation demonstrated reduction of the positively charged surface area in this region, which might reduce binding ability of EDNRB to G protein and lead to abnormal signal transduction underlying the WS phenotype. CONCLUSIONS: Our findings suggested that autosomal recessive mutation in EDNRB may underlie a part of WS1 with the current diagnostic criteria, and supported that Hirschsprung's disease is a multifactorial genetic disease which requires additional factors. Further molecular analysis is necessary to elucidate the gene interaction and to reappraise the current WS classification.
OBJECTIVE: To examine and expand the genetic spectrum of Waardenburg syndrome type 1 (WS1). METHODS: Clinical features related to Waardenburg syndrome (WS) were examined in a five-year old patient. Mutation analysis of genes related to WS was performed in the proband and her parents. Molecular modeling of EDNRB and the p.R319W mutant was conducted to predict the pathogenicity of the mutation. RESULTS: The proband showed sensorineural hearing loss, heterochromia iridis, and dystopia canthorum, fulfilling the clinical criteria of WS1. Genetic analyses revealed that the proband had no mutation in PAX3 which has been known as the cause of WS1, but had a homozygous missense mutation (p.R319W) in endothelin receptor type B (EDNRB) gene. The asymptomatic parents had the mutation in a heterozygote state. This mutation has been previously reported in a heterozygous state in a patient with Hirschsprung's disease unaccompanied by WS, but the patient and her parents did not show any symptoms in gastrointestinal tract. Molecular modeling of EDNRB with the p.R319W mutation demonstrated reduction of the positively charged surface area in this region, which might reduce binding ability of EDNRB to G protein and lead to abnormal signal transduction underlying the WS phenotype. CONCLUSIONS: Our findings suggested that autosomal recessive mutation in EDNRB may underlie a part of WS1 with the current diagnostic criteria, and supported that Hirschsprung's disease is a multifactorial genetic disease which requires additional factors. Further molecular analysis is necessary to elucidate the gene interaction and to reappraise the current WS classification.
Authors: Maan Abdullah Albarry; Muhammad Latif; Ahdab Qasem Alreheli; Mohammed A Awadh; Ahmad M Almatrafi; Alia M Albalawi; Sulman Basit Journal: PLoS One Date: 2021-02-11 Impact factor: 3.240