PMM2 and congenital disorder of glycosylation: The patient was diagnosed with a complete maternal mixed hetero/isodisomy of chromosome 16, with a homozygous pathogenic PMM2 variant (p.Phe119Leu) causing PMM2-CDG.A literature review revealed eight cases of uniparental disomy as an underlying cause of CDG, four of which are PMM2-CDG.<h4>Conclusion</h4>Since the incidence of homozygosity for PMM2 variants is rare, we suggest further investigations for every homozygous PMM2-CDG patient where the segregation does not fit.