 Mutations in the LCAT gene, which is localized in the q21–22 region of chromosome 16, cause fish-eye disease.The mutation in the LCAT gene is homozygous for a Thr123→Ile mutation or Pro10→Leu mutation.New mutations have been identified as homozygosity for an A2205→G nucleotide substitution in exon 4 of the LCAT gene which is predicted to be the cause of an Asp131→Asn substitution.