CASE PRESENTATION: Herein, we report a case of very severe hypertriglyceridemia 32 mmol/L (2834 mg/dL) detected incidentally at three months old in an otherwise well boy born late preterm with intrauterine growth restriction, when he presented with lipaemic plasma. He was later diagnosed with CLS. No pathogenic mutations were found for hypertriglyceridemia, and no secondary causes could explain his very severe hypertriglyceridemia.
CONCLUSIONS: The very severe hypertriglyceridemia in this case may appear to be a serious presentation of an unrecognised clinical feature of CLS, further expanding its phenotype.