Pitfalls in the prenatal diagnosis of mucolipidosis II alpha/beta: A case report

•Biochemical prenatal investigation in amniotic fluid and amniocytes were inconclusive for ML II/III.•DNA analysis showed fetus heterozygous for GNPTAB mutation c.[3503_3504delTC].

Mucolipidosis II alpha/beta is an autosomal recessive disorder caused by deficient activity of GlcNAc-1-phosphotransferase. We report the prenatal diagnosis of a fetus who was found to exhibit normal levels of lysosomal enzymes in the amniotic fluid but low levels in amniocytes, and who was found to be heterozygous for the most common GNPTAB mutation. As in some carriers of Mucolipidosis II biochemical abnormalities may hinder prenatal diagnosis, we suggest DNA analysis should be performed whenever possible.