Abetalipoproteinaemia arising from a new variant of microsomal triglyceride transfer protein in a child presenting with chronic fat malabsorption

This case report describes a patient who failed to thrive and lagged in development in the first year of her life and did not grow as expected. Though a history of diarrhoea was present, stool analysis was not conclusive for malabsorption of fat. Fat malabsorption may be due to various disorders of exocrine function of the pancreas as well as problems in the intestine. Abetalipoproteinaemia is a rare inherited condition in which neither the intestine nor the liver can secrete lipoproteins. This diagnosis was made on lipoprotein investigation by demonstrating the absence of lipoproteins containing apolipoprotein B (apoB). Lipoprotein investigation is generally normal in the parents of the recessively inherited condition of microsomal triglyceride transfer protein (MTTP) deficiency but in homozygous hypobetalipoproteinaemia owing to mutations in apoB that also impair lipoprotein assembly, the parents have low cholesterol concentrations. Patients with abetalipoproteinaemia improve markedly on dietary fat restriction but may benefit from medium-chain triglycerides as part of supplying their energy needs and, importantly, require high doses of vitamin E as well as other fat-soluble vitamins, to avoid neuromuscular degeneration and retinitis pigmentosa.