A Lipid Metabolism Disorder: Abetalipoproteinemia

Abstract

Abetalipoproteinemia (ABL) is an extremely rare disease with only 100 cases approximately reported in the clinical literature worldwide. Virtually absent apolipoprotein B-containing lipoproteins, extremely low vitamin E levels, steatorrhea, and acanthocytosis are hallmarks of this disorder. ABL is a Mendelian metabolic disorder caused by mutations in the MTTP gene encoding the microsomal triglyceride transfer protein large subunit, that lead to a truncated protein. Deficiency of MTTP hinders the production of apolipoprotein B-containing lipoproteins, leading to virtually absent levels of LDL, and VLDL and chylomicrons. The malabsorption of lipids and fat-soluble vitamins A, D, E, and K is linked to a series of gastrointestinal, neurological, ophthalmological, and hematological clinical manifestations. Lifetime monitorization and symptomatic treatment with fat-soluble vitamins and the implementation of a fat-restrictive diet reduces the morbimortality in affected individuals. High-dose vitamin E (50-300 IU/kg/day) and vitamin A (100–400 IU/kg/day) is required to prevent or even reverse neurological and retinal degeneration, respectively. In addition, supplementation of other nutrients and fat-soluble vitamins D and K might be necessary to treat the vast spectrum of clinical manifestations present in ABL. There is currently only symptomatic treatment for ABL. However, in the last few years, new personalized gene therapies using CRISPR/Cas9 gene edition and other approaches have been started to be investigated to treat rare genetic disorders. Therefore, a potentially curative treatment could be developed in the future.