Novel variants in the KERA gene cause autosomal recessive cornea plana in a Chinese family: A case report

Autosomal recessive cornea plana is a very rare hereditary ocular disease, characterized by a flattened corneal curvature, marked hyperopia due to low refractive power and frequently consequent accommodative esotropia. Other features include various cornea anterior segment abnormalities, without systemic problems. The purpose of the present study was to investigate the clinical and molecular alterations in a Chinese family with cornea plana. Full ophthalmic examinations of the patients were performed, including slit-lamp examination, fundus examination and ocular ultrasound. Whole-exome sequencing data were screened for pathological variants in the proband, which were confirmed by Sanger sequencing. One novel missense mutation, c.242A>G (p.N81S) and another novel 7 base-pair deletion mutation, c.772-779del (p.G258Cfs*30), were detected in the keratocan (KERA) gene; two affected siblings inherited these variations in a compound heterozygous state, which were derived from the clinically unaffected heterozygous father (c.772_779del) and mother (c.242A>G), respectively. Neither mutation was observed in unrelated healthy controls (n=200). Multiple computer software predictions supported the pathogenicity of the two variants. Furthermore, protein modeling prediction was performed to better understand the molecular basis of cornea plana, particularly the importance of the leucine-rich repeat domain. This study presents the 14th pathogenic KERA mutations identified worldwide and the first in East Asia so far, to the best of our knowledge. These findings guided prenatal diagnosis for the family in question and expand on the variant spectrum of KERA, therefore facilitating genetic counseling.