Preimplantation genetic diagnosis of Morquio disease

Morquio syndrome is an autosomal recessive disease and mutations in the N-acetylgalactosamine 6-sulfate sulfatase (GALNS) gene cause Morquio type A disease. Preimplantation genetic diagnosis (PGD), an early form of prenatal diagnosis for couples at risk of transmitting inherited diseases, was applied to prevent transmission of this disease.

A couple with three affected children, having homozygous W159C (p. Trp 159 Cys) mutation in GALNS gene, underwent in vitro fertilization (IVF) treatment and PGD. Mutation analyses from the embryos were performed following whole genome amplification of single blastomeres using multiple displacement amplification (MDA).

Three embryos were diagnosed as normal and two were transferred on day 4. The cycle resulted in a pregnancy and a live birth of a carrier male infant. Genetic haplotyping analysis of the infant and the leftover MDA samples enabled us to determine which embryo was implanted. The discrepancy in results was explained by allele dropout (ADO) of the mutant allele from the MDA product.

A feasible strategy for PGD of Morquio disease including whole genome amplification by MDA and the use of preimplantation genetic haplotyping is described. MDA product archiving will be useful for future investigations if needed.