A Case Report of I-Cell Disease (Mucolipidosis Type II) With a Novel Placental-Focused Diagnostic Approach.

Inclusion cell disease (I-cell disease/Mucolipiodsis Type II) is an autosomal recessive lysosomal storage disorder that results in accumulation of substrates (cholesterol, phospholipids, and glycosaminoglycans) in various tissues. The clinical presentation of I-cell disease includes hepatomegaly, splenomegaly, cardiomegaly, upper respiratory infections, skeletal deformities, developmental delay, abnormal facies, and failure to thrive. We describe a case of I-cell disease in a neonate admitted to the Neonatal Intensive Care Unit for respiratory distress with initial suspicion of infection. Placental histopathological findings included syncytiotrophoblast vacuolization and positive lipid vacuoles highlighted with the special stain, Oil Red-O. Ultra-rapid whole genome sequencing from buccal swab identified compound heterozygous GNPTAB variants consistent with I-cell disease. Whole exome sequencing of placental tissue showed concordant pathogenic variants. To our knowledge, this is the first report of Oil Red-O staining of intracytoplasmic lipids within syncytiotrophoblast and successfully identifying variants by sequencing placental DNA in the setting of I-cell disease.