Contributors: Alexandra Elliott, George J. Florakis and Michael P. Vrabec
Abetalipoproteinemia (Bassen-Kornzweig syndrome) is a rare chronic autosomal recessive inherited disorder of lipid absorption associated with retinitis pigmentosa and systemic manifestations that include acanthocytosis and a progressive neuromuscular disturbance. Affected individuals are unable to secrete apolipoprotein B-100 and apolipoprotein B-48. Because of this patients fail to absorb fat and fat-soluble vitamins (vitamin A, vitamin E and vitamin K) and develop steatorrhea and vitamin deficiency syndromes including excessive bleeding due to vitamin K deficiency. Vitamin A is required for the structural integrity of photoreceptors thus develop an atypical retinitis pigmentosa. Two types of abetalipoproteimemia are recognized: classic abetalipoproteinemia [abetalipoproteinemia - classic] and normotriglyeridemic abetaliproteinemia [abetalipoproteinemia - normotriglyceridemic].
Patients are afflicted from birth with poor appetite, loose stools, and failure to thrive. These patients have slow psychomotor development and develop severe ataxia by the age of 20. Night blindness is secondary to rod degeneration in an atypical retinitis pigmentosa fashion. Treatment with vitamin A has been shown to restore ERG responses to normal if instituted early enough in life. The restoration is complete with 24 hours of administration.