PMC3658229_01
Genotyping of kindred. Single nucleotide polymorphisms in A) ATP6V0A4 and in B) ATP6V1B1 were subject to polymerase chain reaction amplification followed by specific restriction digestion, and this was used to assess linkage to both genes. Details of these single nucleotide polymorphisms are shown in Table 1. Filled symbols are affected individuals whereas unfilled symbols are unaffected individuals. Arrow denotes index case. C) Mutations in ATP6V0A4 were identified by DNA sequencing. Upper traces are representative of the heterozygous alterations in codon 770 and 807 in both children and one affected parent. Lower traces show wild-type sequences from the unaffected parent. Translation products of the sense strand are shown, with altered products in color. In codon 770, the C > T transition introduces a premature stop codon. In codon 807, the G > A transition results in the substitution of glutamine for arginine.
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As displayed in Figure 2A and B, linkage could not be excluded to either of these loci because the children were haploidentical at both (by state at ATP6V0A4 and by descent at ATP6V1B1). Representative sequence traces are shown in Figure 2C. DNA sequencing of both parents in the present family confirmed that the two mutations had been inherited in trans by both children (Figure 2C).