Pregnancy in a Woman with PGM1-CDG: Longitudinal Metabolic Follow-up During a Lactose-Supported Diet

Phosphoglucomutase-1 deficiency (PGM1-CDG) is an ultra-rare, treatable congenital disorder of glycosylation characterized by multisystem involvement. Although galactose supplementation improves biochemical and clinical manifestations, data on pregnancy management and metabolic follow-up in affected women remain extremely limited. We report a woman with genetically confirmed PGM1-CDG who achieved a successful pregnancy with detailed longitudinal metabolic monitoring and maintenance of galactose intake through a lactose-supported diet. The patient was diagnosed during adolescence with a multisystem phenotype including short stature, craniofacial dysmorphism, hepatic involvement, elevated creatine kinase, reduced antithrombin III and left ventricular hypertrophy. She harbored a homozygous PGM1 c.1508G>A (p.Arg503Gln) variant. Long-term pharmaceutical D-galactose supplementation was associated with biochemical improvement, while cardiac involvement remained clinically stable. At 25 years of age, pregnancy was achieved through assisted reproductive technology with her spouse, who was heterozygous for a different PGM1 variant classified as a variant of uncertain significance (VUS). Given the limited safety data on pharmaceutical D-galactose use during pregnancy and uncertainty regarding potential fetal effects, galactose intake was maintained through a lactose-supported diet (estimated galactose intake of approximately 0.5 g/kg/day). Liver enzymes, coagulation parameters and cardiac status remained stable and creatine kinase levels did not worsen. Gestational diabetes was successfully managed with dietary modification alone. No thrombotic, hepatic or cardiac complications occurred. A healthy female infant was delivered by elective cesarean section at 38 weeks. The newborn had a normal metabolic evaluation and was a heterozygous carrier of the maternal PGM1 variant. This case provides detailed longitudinal data on pregnancy in PGM1-CDG and describes the maintenance of dietary galactose intake derived from lactose during a pregnancy with favorable maternal and neonatal outcomes.