APOB and Pigmentary retinopathy: The clinical phenotype of heterozygous FHBL is usually mild, characterized only by fatty liver, however patients with homozygous or compound heterozygous APOB mutations may have severe biochemical and clinical phenotype, similar to the abetalipoproteinemia (caused by mutations in microsomal TG transfer protein “MTP” gene), characterized by intestinal malabsorption, pigmentary retinal degeneration, ataxic neuropathy, and almost undetectable levels of LDL-C and APOB.20