A Survey of Multigenic Protein-Altering Variant Frequency in Familial Exudative Vitreo-Retinopathy (FEVR) Patients by Targeted Sequencing of Seven FEVR-Linked Genes

Genes (Basel). 2022 Mar 11;13(3):495. doi: 10.3390/genes13030495.


While Inherited Retinal Diseases (IRDs) are typically considered rare diseases, Familial Exudative Vitreo-Retinopathy (FEVR) and Norrie Disease (ND) are more rare than retinitis pigmentosa. We wanted to determine if multigenic protein-altering variants are common in FEVR subjects within a set of FEVR-related genes. The potential occurrence of protein-altering variants in two different genes has been documented in a very small percentage of patients, but potential multigenic contributions to FEVR remain unclear. Genes involved in these orphan pediatric retinal diseases are not universally included in available IRD targeted-sequencing panels, and cost is also a factor limiting multigenic-sequence-based testing for these rare conditions. To provide an accurate solution at lower cost, we developed a targeted-sequencing protocol that includes seven genes involved in Familial Exudative Vitreo-Retinopathy (FEVR) and Norrie disease. Seventy-six DNA samples from persons refered to clinic with possible FEVR and some close relatives were sequenced using a novel Oakland-ERI orphan pediatric retinal disease panel (version 2) providing 900 times average read coverage. The seven genes involved in FEVR/ND were: NDP (ChrX), CTNNB1 (Chr3); TSPAN12 (Chr7); KIF11 (Chr10), FZD4 (Chr11), LRP5 (Chr11), ZNF408 (Chr11). A total of 33 variants were found that alter protein sequence, with the following relative distribution: LRP5 13/33 (40%), FZD4 9/33 (27%), ZNF408 6/33 (18%), (KIF11 3/33 (9%), NDP 1/33 (3%), CTNNB1 1/33 (3%). Most protein-altering variants, 85%, were found in three genes: FZD4, LRP5, and ZNF408. Four previously known pathogenic variants were detected in five families and two unrelated individuals. Two novel, likely pathogenic variants were detected in one family (FZD4: Cys450ter), and a likely pathogenic frame shift termination variant was detected in one unrelated individual (LRP5: Ala919CysfsTer67). The average number of genes with protein-altering variants was greater in subjects with confirmed FEVR (1.46, n = 30) compared to subjects confirmed unaffected by FEVR (0.95, n = 20), (p = 0.009). Thirty-four percent of persons sequenced had digenic and trigenic protein-altering variants within this set of FEVR genes, which was much greater than expected in the general population (3.6%), as derived from GnomAD data. While the potential contributions to FEVR are not known for most of the variants in a multigenic context, the high multigenic frequency suggests that potential multigenic contributions to FEVR severity warrant future investigation. The targeted-sequencing format developed will support such exploration by reducing the testing cost to $250 (US) for seven genes and facilitating greater access to genetic testing for families with this very rare inherited retinal disease.

Keywords: DNA sequencing; FEVR; NGS; inherited retinal disease; multigenic; pediatric; protein variants; retinal disease; targeted sequencing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blindness / congenital
  • Child
  • DNA Mutational Analysis
  • DNA-Binding Proteins / genetics
  • Familial Exudative Vitreoretinopathies / genetics
  • Frizzled Receptors / metabolism
  • Genetic Diseases, X-Linked
  • Humans
  • Low Density Lipoprotein Receptor-Related Protein-5* / genetics
  • Low Density Lipoprotein Receptor-Related Protein-5* / metabolism
  • Mutation
  • Nervous System Diseases
  • Retinal Degeneration
  • Retinal Diseases* / metabolism
  • Spasms, Infantile
  • Tetraspanins / genetics
  • Tetraspanins / metabolism
  • Transcription Factors / genetics


  • DNA-Binding Proteins
  • FZD4 protein, human
  • Frizzled Receptors
  • Low Density Lipoprotein Receptor-Related Protein-5
  • TSPAN12 protein, human
  • Tetraspanins
  • Transcription Factors
  • ZNF408 protein, human

Supplementary concepts

  • Norrie disease