Key result
Heterozygous familial hypobetalipoproteinemia with apoB truncations was associated with significantly reduced VLDL apoB-100 production rates compared to controls (7.7 vs 21.2 mg/kg/d, P=0.002).
Why the study?
Does heterozygous familial hypobetalipoproteinemia with apoB truncations reduce apoB-100 production rates compared to unaffected controls?
Case-Control (n=16)
Does heterozygous familial hypobetalipoproteinemia with apoB truncations reduce apoB-100 production rates compared to unaffected controls?
Absolute Event Rate: 7.7% vs 21.2%
p-value: p=.002
Heterozygous familial hypobetalipoproteinemia with apoB truncations results in apoB-100 production rates that are approximately 30% of normal, explaining the lower than expected plasma levels of apoB-100 and LDL cholesterol.
Accounts for low apoB/LDL-C in FHBL; leaves open effects on ASCVD risk.
Among individuals who are heterozygous for familial hypobetalipoproteinemia (FHBL) and who have various truncations of apoprotein (apo) B (ie, FHBL with apoB truncation/apoB-100 genotypes), the plasma concentrations of apoB-100 are typically approximately 30% rather than the expected approximately 50% of those in unaffected family members. The metabolic basis for the low apoB-100 levels is unknown. Therefore, we compared the metabolism of apoB-100 in 8 subjects with heterozygous FHBL (2 apoB-89/apoB-100, 2 apoB-75/apoB-100, 2 apoB-54.8/apoB-100, 1 apoB-52/apoB-100, and 1 apoB-31/apoB-100) with the metabolism of apoB-100 in 8 apoB-100/apoB-100 control subjects who were paired with the heterozygotes by gender, age, height, weight, and race. Endogenous labeling of apoB-100 with [13C]leucine and a multicompartmental kinetic model were used to obtain kinetic parameters. FHBL heterozygotes had significantly reduced VLDL apoB-100 production rates (7.7 +/- 3.7 versus 21.2 +/- 6.2 mg.kg-1.d-1, P = .002) and LDL apoB-100 production rates (4.5 +/- 3.12 versus 15.3 +/- 1 mg.kg-1.d-1, P = .05) compared with control subjects. Fractional conversion rates of VLDL to LDL were not significantly different (0.67 +/- 0.36 versus 0.77 +/- 0.17 pools/d), and the respective fractional catabolic rates of apoB-100 in VLDL, IDL, and LDL also were similar in both groups. Thus, FHBL heterozygotes produced apoB-100 at about 30% of the rates of control subjects. We believe these reduced production rates largely account for the lower than expected levels of apoB-100 and LDL cholesterol in the plasma of FHBL heterozygotes.
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Aguilar‐Salinas et al. (1995) conducted a case-control in Familial hypobetalipoproteinemia (FHBL) (n=16). Heterozygous familial hypobetalipoproteinemia (FHBL) with apoB truncations vs. apoB-100/apoB-100 control subjects was evaluated on VLDL apoB-100 production rates (mg.kg-1.d-1) (p=.002). Heterozygous familial hypobetalipoproteinemia with apoB truncations was associated with significantly reduced VLDL apoB-100 production rates compared to controls (7.7 vs 21.2 mg/kg/d, P=0.002).
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