Fig. 2

Mutant sequences and protein alignment. a Genomic DNA sequences showing HEXB variants. Noted heterozygous c.761T>C (p.Leu254Ser) in patient-4, homozygous c.1652G>A (p.Cys551Tyr) in patient-1, and sequence of normal control on side by side. b PCR-PsiI restriction digest. Noted the c.1652G>A mutant allele creating a Psil restriction site, yielding 179 and 191 bp allele in homozygous individuals (patient-1, −2 and − 3 in lanes 2, 4 and 6, respectively) whereas heterozygous individuals harbored the uncut normal allele of 370 bp in addition to the 179 and 191 bp from the mutant allele (unaffected brother of patient-1 and the mother of patient-2 in lanes 3 and 5, respectively). c Protein sequence alignment of HEXB across various vertebrate species. Noted highly conserved nature of the Cysteine551 and the Leucine254 residues