Analysis of HEXB gene mutations in an infant with Sandhoff disease

Objective To detect potential mutations of HEXB gene in an infant with Sandhoff disease (SD). Methods Genomic DNA was extracted from peripheral blood sample of the infant. All coding exons (exons 1 to 14) and splicing sites of the HEXB gene were subjected to PCR amplification and direct sequencing.PubMed Protein BLAST system was employed to analyze cross-species conservation of the mutant amino acid. PubMed BLAST CD-search was performed to identify functional domains destroyed by thecandidate mutations. Impact of the mutations was analyzed with software including PolyPhen-2, Mutation Taster and SIFT. Whole-exome sequencing was carried out to identify additional mutations. Results The infant was found to carry compound heterozygous mutations c. 1652G>A(p.Cys551Tyr) and c. 1389C>G (p.Tyr463*) of the HEXB gene. The c. 1389C>G (p.Tyr463*) mutation may lead to destruction of two functional domains in β subunit of the Hex protein. The c. 1652G>A(p.Cys551Tyr)mutation, unreported previously, was predicted to be probably damaging by Bioinformatic analysis. Conclusion Compound heterozygous mutations c. 1652G>A(p.Cys551Tyr) and c. 1389C>G (p.Tyr463*) in the HEXB gene probably underlie the disease in this patient. Key words: HEXB gene; Infantile Sandhoff disease; Compound heterozygous mutation; Nonsense mutation