Figure 2. Loss of expression of mutant allele due to IVS2+1 G>A splice-site mutation identified in family 1.

PCR and sequencing analysis from the genomic DNA of a mutation carrier from family 1 shows heterozygous state of SNP rs2277257 (G/A). Subsequent RT–PCR and sequencing analysis of SLC29A3 transcript shows lack of the ‘G’ allele and therefore loss of mRNA expression.