[Applying multiplex ligation-dependent probe amplification in the diagnosis of 5 cases with ornithine transcarbamylase deficiency].

OBJECTIVE

To detect large genomic deletions or duplications of ornithine transcarbamylase (OTC) gene by multiplex ligation-dependent probe amplification (MLPA).

METHOD

Thirty cases of suspected OTC deficiency (OTCD) patients based on tandem-mass spectrum results were recruited in Xinhua Hospital from 2012 to 2014, among whom 13 were male and 17 were female. Sanger sequencing of OTC gene revealed mutations in 23 cases. MLPA was performed in the patients whose previous Sanger sequencing failed to detect any disease-causing mutation. The samples were treated via the steps of DNA degeneration, the probe hybridization, connecting the hybridization probe, PCR amplification and capillary electrophoresis. The data were analyzed using Coffalyser software.

RESULT

Abnormal MLPA results were found in 5 patients without mutation detected in previous Sanger sequencing. Patient 1, a 9-year old girl, had a heterozygous deletion of Exon 2-4. Patient 2, a male newborn, died 10 days after birth. The examination of the mother's sample by MLPA revealed a heterozygous duplication of exon 2-6. Patient 3, a 10-day old boy, was found to harbor a hemizygous deletion of exon 7-10. Patient 4, a 2-year old girl, harbored a heterozygous deletion of exon 1-4. The fifth patient died at the age of 6 years, and his mother carried a heterozygous duplication of exon 1-4.

CONCLUSION

MLPA can be helpful in detecting the OTC gene defects, particularly for OTCD patients without mutation detected by Sanger sequencing.