A PMM2-CDG caused by an A108V mutation associated with a heterozygous 70 kilobases deletion case report.

We report in the present paper the largest known heterozygous deletion of a PMM2 gene. The observation reveals the impact of a precise diagnostic on genetic counselling: by using WGS, an erroneous conclusion of homozygosity in the case of a relatively rare variant could be avoided, and an index patient with healthy and unrelated parents correctly identified.