Proband’s mother (subject I.1 in Table 2) had low plasma lipid levels suggestive of hypobetalipoproteinemia, even though, the lipid plasma values within the lower limit or low values of TC and apoB were observed in heterozygous subjects for the same mutation (c.923 G > A) in a previous study [10]. The gene discussed is APOB; the disease is hypobetalipoproteinemia.