title: Targeted next-generation sequencing reveals novel USH2A mutations associated with diverse disease phenotypes: implications for clinical and molecular diagnosis.
abstract: USH2A mutations have been implicated in the disease etiology of several inherited diseases, including Usher syndrome type 2 (USH2), nonsyndromic retinitis pigmentosa (RP), and nonsyndromic deafness. The complex genetic and phenotypic spectrums relevant to USH2A defects make it difficult to manage patients with such mutations. In the present study, we aim to determine the genetic etiology and to characterize the correlated clinical phenotypes for three Chinese pedigrees with nonsyndromic RP, one with RP sine pigmento (RPSP), and one with USH2. Family histories and clinical details for all included patients were reviewed. Ophthalmic examinations included best corrected visual acuities, visual field measurements, funduscopy, and electroretinography. Targeted next-generation sequencing (NGS) was applied using two sequence capture arrays to reveal the disease causative mutations for each family. Genotype-phenotype correlations were also annotated. Seven USH2A mutations, including four missense substitutions (p.P2762A, p.G3320C, p.R3719H, and p.G4763R), two splice site variants (c.8223+1G>A and c.8559-2T>C), and a nonsense mutation (p.Y3745*), were identified as disease causative in the five investigated families, of which three reported to have consanguineous marriage. Among all seven mutations, six were novel, and one was recurrent. Two homozygous missense mutations (p.P2762A and p.G3320C) were found in one individual family suggesting a potential double hit effect. Significant phenotypic divergences were revealed among the five families. Three families of the five families were affected with early, moderated, or late onset RP, one with RPSP, and the other one with USH2. Our study expands the genotypic and phenotypic variability relevant to USH2A mutations, which would help with a clear insight into the complex genetic and phenotypic spectrums relevant to USH2A defects, and is complementary for a better management of patients with such mutations. We have also demonstrated that a targeted NGS approach is a valuable tool for the genetic diagnosis of USH2 and RP.
authors.affiliation: Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, State Key Laboratory of Reproductive Medicine, Nanjing, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Chen
authors.affiliation: Ningxia Eye Hospital, Ningxia People's Hospital, Ningxia, China.
authors.forename: Xunlun
authors.initials: X
authors.lastname: Sheng
authors.affiliation: Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, State Key Laboratory of Reproductive Medicine, Nanjing, China.
authors.forename: Xiaoxing
authors.initials: X
authors.lastname: Liu
authors.affiliation: Ningxia Eye Hospital, Ningxia People's Hospital, Ningxia, China.
authors.forename: Huiping
authors.initials: H
authors.lastname: Li
authors.affiliation: Ningxia Eye Hospital, Ningxia People's Hospital, Ningxia, China.
authors.forename: Yani
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Ningxia Eye Hospital, Ningxia People's Hospital, Ningxia, China.
authors.forename: Weining
authors.initials: W
authors.lastname: Rong
authors.affiliation: Ningxia Eye Hospital, Ningxia People's Hospital, Ningxia, China.
authors.forename: Shaoping
authors.initials: S
authors.lastname: Ha
authors.affiliation: Ningxia Eye Hospital, Ningxia People's Hospital, Ningxia, China.
authors.forename: Wenzhou
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Kang
authors.affiliation: Tianjin Medical University, Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin, China.
authors.forename: Kanxing
authors.initials: K
authors.lastname: Zhao
authors.affiliation: Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, State Key Laboratory of Reproductive Medicine, Nanjing, China; State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat Sen University, Guangzhou, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhao
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D044466:Asian People / Q000235:genetics; D004252:DNA Mutational Analysis; D016326:Extracellular Matrix Proteins / Q000737:chemistry / Q000235:genetics*; D005260:Female; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D020125:Mutation, Missense; D010375:Pedigree; D010641:Phenotype; D016415:Sequence Alignment; D052245:Usher Syndromes / Q000175:diagnosis* / Q000235:genetics*; D055815:Young Adult
chemical_list: D016326:Extracellular Matrix Proteins; C112735:USH2A protein, human