Abstract
We report on acanthocytosis in a 31‐year‐old woman with homozygous familial hypobetalipoproteinemia due to a mutation affecting the splicing of the APOB gene encoding apolipoprotein B. Treatment with fat‐soluble vitamins was associated with arrest of the usually progressive neurological complications of this condition. However, the acanthocytosis – literally ‘thorny’ erythrocytes that result from abnormal membrane fluidity – persists despite treatment.