LDL-cholesterol in newborns and children with genetically verified familial hypercholesterolaemia: implications for cholesterol-based screening.

BACKGROUND AND AIMS Cholesterol screening in children, with subsequent genetic testing of top percentile, has been suggested as an efficient universal screening approach in familial hypercholesterolaemia (FH). The potential cholesterol-based screening efficacy was investigated in a national genetically based screening programme. METHODS Data were from the Norwegian national family cascade screening programme in FH children from 1998 to 2023. Cholesterol levels [umbilical cord in newborns (n = 113) and venous blood in children 1-12 years old (n = 1346)] in variant positive and variant negative children were compared. RESULTS LDL cholesterol (LDL-C) was higher in FH newborns vs non-FH newborns [1.22 (.48) vs .68 (.32) mmol/L, P < .001], but overlapped widely. Cut-off levels corresponding to the 95th and 85th percentile would only identify 55.7% and 75.4% of newborns with FH, respectively. Screening efficacy in newborns did not differ in subgroups: boys and girls, null and non-null variants, variant gene, and neither for total cholesterol nor for non-HDL cholesterol. In all other age groups (from 1 to 12 years), LDL-C discriminated highly between mutation FH and non-FH children. Cut-off levels corresponding to 95th and 85th percentile of LDL-C would identify 88.4% and 94.1% of 1-12-year-old children with FH, respectively. CONCLUSIONS Previous studies investigating lipid or genetic screening approaches for FH have limitations of only performing genetic testing in children with high LDL-C levels. The present study is the first to show the true LDL-C overlap in children with FH vs non-FH by utilizing unique data from a national family cascade screening programme. Cholesterol-based screening approaches for FH only seem feasible from 1 year of age onward.