Two siblings with severe hyperchylomicronemia and encephalopathy in early infancy are reported from Starship Children’s Hospital, Aukland, New Zealand. Case 1 presented at 5 weeks of age with tachypnea, feeding problems, and lethargy, which followed a viral upper respiratory tract illness. Parents were second cousins, and some family members had died suddenly in infancy of unexplained illness. Abnormal physical signs included hypotonia, macrocephaly, a white retina, and hepatosplenomegaly. Venous blood was grossly hyperlipemic and appeared “strawberry cream” in color. Triglycerides and cholesterol were grossly elevated, secondary to lipoprotein lipase deficiency. After omitting breast milk and substituting a medium chain triglyceride formula (Monogen), the plasma triglyceride level fell slowly toward normal. MRI showed lipid deposition throughout the brain. Despite correction of lipid blood levels, she had severe developmental delay at 18 month follow-up, and the MRI was unchanged. Plasma apolipoprotein C-II, the lipoprotein responsible for activation of lipoprotein lipase, was absent in the patient and a sibling, also affected (Patient 2), and was below reference levels in all other family members. The sibling who was treated early developed normally. Both patients had a novel homozygous point mutation on sequencing of the APO-C-II gene. The parents and all other siblings were heterozygotes. [1]
COMMENT. This rare infantile “lipid encephalopathy” due to apolipoprotein C-II deficiency, and characterized by severe psychomotor retardation, pink venous blood, macrocephaly, a white retina (lipid retinalis), and hepatosplenomegaly, may be amenable to treatment with a low fat diet that corrects the hyperchylomicronemia.