OBJECTIVETo apply high-throughput sequencing for the detection of potential mutation in a methylmalonic academia pedigree for which no proband was available.

METHODSFor a couple who had previously given birth to an affected child, 14 genes were re-sequenced by high-throughput sequencing. Suspected mutations were validated by Sanger sequencing. Specific mutations were tested for amniotic fluid sample from the fetus.

RESULTSHigh-throughput sequencing suggested that the husband has carried a heterozygous mutation of the MUT gene (Exon 3: c.729_730insTT; p.Asp244Leufs*39), while the wife also carried a heterozygous mutation of the MUT gene (Exon 5: c.914T>C; p.Leu305Ser). Both mutations were confirmed by Sanger sequencing. Testing of amniotic sample suggested that the fetus has carried neither mutation. Follow-up has found no sign of methylmalonic academia in the neonate.

CONCLUSIONHigh-throughput sequencing is a sensitive method to screen a bunch of genes in a single test. For autosomal recessive diseases, when no proband is available, carrier testing for both parents with high-throughput sequencing can provide an alternative approach, though great caution should be taken in the setting of prenatal diagnosis.