Infantile free sialic acid storage disease presenting as non-immune hydrops fetalis

A preterm, 33 weeks of gestational age, was antenatally diagnosed with hydrops fetalis. There is positive family history of two early neonatal death of unknown cause on his maternal side. He had generalized edema, massive ascites, blonde hair, unexpectedly fair skin, coarse facies, telangiectasia over the trunk, abdomen, and face. Abdominal paracentesis showed no urine, no bilirubin and no chylous fluid. Several clinical investigations ruled out the most common diagnoses. Finally, genetic analysis by whole exome sequencing showed a homozygous splicing site c.979-1G>T mutation in SLC17A5 gene causing infantile free sialic acid storage disease. Both parents were found to be heterozygous. Despite all supportive measurements, the baby died at the age of 6 months.