# A genetic investigation in five Chinese families with keratoconus

## TL;DR

This study identifies five new genetic variants in Chinese families with keratoconus, which could help in early diagnosis before symptoms appear.

## Contribution

The study reports five novel gene variants in HOMER3, IGF1R, EML6, DOP1B, and NBEAL2 associated with keratoconus in Chinese families.

## Key findings

- Five new heterozygous variants in HOMER3, IGF1R, EML6, DOP1B, and NBEAL2 genes were identified in keratoconus families.
- The variants were predicted to be pathogenic and associated with keratoconus pathogenesis.
- The findings may aid in early diagnosis of keratoconus before clinical symptoms develop.

## Abstract

This study investigated the genetic characteristics of five Chinese families with keratoconus (KC).

In the five families affected by KC, medical records, clinical observations, and blood samples were collected from all individuals. All KC family members (n = 20) underwent both whole exome sequencing of genomic DNA and Sanger sequencing to confirm the variants. Online software was utilized to analyze all variants, and the online server I-TASSER was employed for in silico predictions of the three-dimensional protein structures of the variants. The newly discovered variants and single nucleotide polymorphisms were further examined in 322 sporadic KC patients.

The Pentacam tomographic composite index in those affected first-degree family members of the probands showed a pathological change. Five new variants were detected in the five probands and other affected members in their families: a heterozygous missense variant g.19043832C>T (p.Ser145Asn) in the homer scaffolding protein 3 (HOMER3) gene; a heterozygous missense variant g.99452113G>A (p.Gly483Arg) in the insulin-like growth factor 1 receptor (IGF1R) gene; a heterozygous missense variant g.55118280G>T (p.Trp843Leu) in the echinoderm microtubule-associated protein like 6 (EML6) gene; a heterozygous frameshift variant c. 1226_1227del (p.Gln410Glufs*17) in the DOP1 leucine zipper-like protein B (DOP1B) gene; and a heterozygous splice-site variant c.7776+2T>A in the neurobeachin-like protein 2 (NBEAL2) gene. These variations were predicted to be potentially pathogenic and associated with KC.

Five novel variants in HOMER3, IGF1R, EML6, DOP1B, and NBEAL2 genes were identified in this study and may be associated with the pathogenesis of KC. This study provides new information about the gene variants and their protein changes in KC patients. The findings should be explored further and could potentially be applied to the early diagnosis of KC before clinical onset.