Since in most of the introns of the human gene A is present in this position it is likely that the presence of a G in this position, like in our patient, disrupts the splicing process.This hypothesis is supported by the observation that proband’s sister who has also hypobetalipoproteinemia was carrier of the same mutation in intron 8. This mutation has not yet been found in normal subjects and in more than 30 FHBL individuals investigated by our group.In FHBL the variability in symptoms was related to the length of the truncated apoB and its ability to form chylomicrons and absorb fat-soluble vitamins and essential fatty acids rather than the levels of LDL-C). Our patient belongs to our series of “symptomatic” heterozygous FHBL subjects with no truncated apoBs detectable in plasma. This finding raises the question as to whether, in a specific FHBL patient/pedegree, hypobetalipoproteinemia is due to mutation in the APOB gene or in other genes (yet to be identified) affecting apoB metabolism. Probably, hypobetalipoproteinemia explains the presence of liver steatosis already at this age, even if it cannot be excluded that obesity should play a role in this alteration.
Familial Hypobetalipoproteinemia Due to a Novel Mutation of Apolipoprotein B Gene " - Horm Res 2004; / Iughetti, Lorenzo; Tarugi, Patrizia Maria; A., Tozzola; Predieri, Barbara; S., Lancellotti; F., Balli; S. B., Calandra. - In: HORMONE RESEARCH. - ISSN 0301-0163. - STAMPA. - 62 (S2):(2004), pp. 198-198. (Intervento presentato al convegno 43rd Annual ESPE Meeting tenutosi a Basel nel 10-13 settembre 2004).