The molecular lesion is a G to T transversion at base pair 87,492,706 (v38) on chromosome 7 or base pair 737 in the GenBank genomic region NC_000073, which corresponds to nucleotide 706 in the mRNA sequence NM_011661 within exon 5 of 5 total exons. The mutation results in a leucine (L) to phenylalanine (F) substitution at amino acid position 215 (L215F) of the protein.