The homozygous Amish founder MTPAP variant (Chr10[GRCh38]:g.30313926T>C, NM_018109.3:c.1432 A>G; p.[Asn478Asp]), marked as pathogenic by ClinVar (VCV000018391.1) and known to cause mild-moderate developmental delay, optic atrophy, and spastic ataxia, was also identified in Individual 2, likely explaining these phenotypic features.24 Compound heterozygous novel pathogenic missense and nonsense HYAL2 variants were identified in Individual 3 (Chr3[GRCh38]:g.50319661G>A, NM_003773.4:c.829C>T; p.[Arg277Cys], Chr3[GRCh38]:g.50319607G>A, NM_003773.4:c.883C>T; p.[Arg295*]). This evidence concerns the gene HYAL2 and hereditary optic atrophy.