title: Novel TMEM98 mutations in pedigrees with autosomal dominant nanophthalmos.
abstract: OBJECTIVE
  Autosomal dominant nanophthalmos is an inherited eye disorder characterized by a structurally normal but smaller eye. Patients with nanophthalmos have high hyperopia (far-sightedness), a greater incidence of angle-closure glaucoma, and increased risk of surgical complications. In this study, the clinical features and the genetic basis of nanophthalmos were investigated in two large autosomal dominant nanophthalmos pedigrees.
  
  
  METHODS
  Fourteen members of a Caucasian pedigree from the United States and 15 members of a pedigree from the Mariana Islands enrolled in a genetic study of nanophthalmos and contributed DNA samples. Twenty of 29 family members underwent eye examinations that included measurement of axial eye length and/or refractive error. The genetic basis of nanophthalmos in the pedigrees was studied with linkage analysis, whole exome sequencing, and candidate gene (i.e., TMEM98) sequencing to identify the nanophthalmos-causing gene.
  
  
  RESULTS
  Nine members of the pedigree from the United States and 11 members of the pedigree from the Mariana Islands were diagnosed with nanophthalmos that is transmitted as an autosomal dominant trait. The patients with nanophthalmos had abnormally short axial eye lengths, which ranged from 15.9 to 18.4 mm. Linkage analysis of the nanophthalmos pedigree from the United States identified nine large regions of the genome (greater than 10 Mbp) that were coinherited with disease in this family. Genes within these "linked regions" were examined for disease-causing mutations using exome sequencing, and a His196Pro mutation was detected in the TMEM98 gene, which was recently reported to be a nanophthalmos gene. Sanger sequencing subsequently showed that all other members of this pedigree with nanophthalmos also carry the His196Pro TMEM98 mutation. Testing the Mariana Islands pedigree for TMEM98 mutations identified a 34 bp heterozygous deletion that spans the 3' end of exon 4 in all affected family members. Neither TMEM98 mutation was detected in public exome sequence databases.
  
  
  CONCLUSIONS
  A recent report identified a single TMEM98 missense mutation in a nanophthalmos pedigree. Our discovery of two additional TMEM98 mutations confirms the important role of the gene in the pathogenesis of autosomal dominant nanophthalmos.
authors.affiliation: Marianas Eye Institute, Saipan, Northern Mariana Islands.
authors.forename: David
authors.initials: D
authors.lastname: Khorram
authors.affiliation: Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa ; The Wynn Institute for Vision Research, University of Iowa.
authors.forename: Michael
authors.initials: M
authors.lastname: Choi
authors.affiliation: Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa ; The Wynn Institute for Vision Research, University of Iowa.
authors.forename: Ben R
authors.initials: BR
authors.lastname: Roos
authors.affiliation: Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa ; The Wynn Institute for Vision Research, University of Iowa.
authors.forename: Edwin M
authors.initials: EM
authors.lastname: Stone
authors.affiliation: Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa ; The Wynn Institute for Vision Research, University of Iowa.
authors.forename: Teresa
authors.initials: T
authors.lastname: Kopel
authors.affiliation: Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa ; The Wynn Institute for Vision Research, University of Iowa.
authors.forename: Richard
authors.initials: R
authors.lastname: Allen
authors.affiliation: Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa ; The Wynn Institute for Vision Research, University of Iowa.
authors.forename: Wallace L M
authors.initials: WL
authors.lastname: Alward
authors.affiliation: Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa ; The Wynn Institute for Vision Research, University of Iowa.
authors.forename: Todd E
authors.initials: TE
authors.lastname: Scheetz
authors.affiliation: Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa ; The Wynn Institute for Vision Research, University of Iowa.
authors.forename: John H
authors.initials: JH
authors.lastname: Fingert
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D058452:Axial Length, Eye; D059472:Exome; D005260:Female; D015870:Gene Expression; D008040:Genetic Linkage; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis* / Q000208:ethnology / Q000235:genetics* / Q000473:pathology; D006579:Heterozygote; D006801:Humans; D006956:Hyperopia / Q000175:diagnosis* / Q000208:ethnology / Q000235:genetics* / Q000473:pathology; D062312:Islands; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008850:Microphthalmos / Q000175:diagnosis* / Q000208:ethnology / Q000235:genetics* / Q000473:pathology; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D044468:Native Hawaiian or Pacific Islander; D010375:Pedigree; D012030:Refractive Errors; D014481:United States; D044465:White People
chemical_list: D008565:Membrane Proteins; C000592526:TMEM98 protein, human