The Genetic Spectrum of Familial Hypercholesterolemia (FH) in the Iranian Population.

Familial hypercholesterolemia (FH) is an autosomal dominant disorder associated with premature cardiovascular disease (CVD). Mutations in the LDLR, APOB, and PCSK9 genes are known to cause FH. In this study, we analysed the genetic spectrum of the disease in subjects from the Iranian population with a clinical diagnosis of FH. Samples were collected from 16 children and family members from five different cities of Iran. Probands were screened for mutations in the LDLR, APOB, and PCSK9 genes using next generation sequencing, with results confirmed by Sanger sequencing. The likely pathology of identified variants was examined using in silico tools. Of the probands, 14 had a clinical diagnosis of homozygous FH and two of heterozygous FH. No mutations were found in either APOB or PCSK9, but nine probands were homozygous for seven different LDLR mutations, with p.(Trp577Arg) occurring in three and p.Val806Glyfs*11 occurring in two patients. Two mutations were novel: p.(Leu479Gln) and p.(Glu668*). Seven probands with a clinical diagnosis of FH were mutation negative. This pilot study, integrating clinical and molecular-based techniques, begins to elucidate the FH heterogeneity and the mutation spectrum in the Iranian population. Such information is important for future disease management and cost savings.

Molecular analysis of the LDLR gene in coronary artery disease patients from the Indian population.

BACKGROUND: Cardiovascular disease is a leading cause of mortality in Indian population. Mutations in LDLR, APOB and PCSK9 genes may lead to Familial Hypercholesterolemia, an autosomal dominant disorder which in turn leads to cardiovascular diseases. The primary objective of this study is to analyze these genes in CAD patients of Indian population. METHODS: A total of 30 patients were selected out of 300 CAD patients based on UK-Simon Broome criteria from South India. The gDNA was isolated by organic extraction method and the exons and exon-intron boundaries of LDLR gene, APOB (exon 26) and PCSK9 (exon 7) were screened by PCR-high resolution melt analysis. The amplicons showing shift in melting pattern were sequenced to find out the variation. RESULTS: This study reports three novel variations, an intronic deletion c.694+8_694+18del in intron 4, a synonymous variation c.966 C>T [p. (N322=)] in exon 7 and a deletion insertion c.1399_1340delinsTA [p. (T467Y)] in exon 10, two recurrent variations c.862G>A [p. (E288K)] in exon 6 and a splice site variation c.1845+2T>C in exon-intron junction of exon 12 in LDLR gene and PCSK9 gene had c.1180+17C>T change in intron 7. However there are no pathogenic variations in APOB and PCSK9 genes in Indian population. In silico analysis predicted all the variations as pathogenic except the synonymous variation. CONCLUSION: This report adds five new variations to the spectrum of LDLR variations in Indian population. This study also suggests that UK Simon Broom criteria can be followed to categorize FH patients in Indian population.

Would raising the total cholesterol diagnostic cut-off from 7.5 mmol/L to 9.3 mmol/L improve detection rate of patients with monogenic familial hypercholesterolaemia?

A previous report suggested that 88% of individuals in the general population with total cholesterol (TC) > 9.3 mmol/L have familial hypercholesterolaemia (FH). We tested this hypothesis in a cohort of 4896 UK civil servants, mean (SD) age 44 (±6) years, using next generation sequencing to achieve a comprehensive genetic diagnosis. 25 (0.5%) participants (mean age 49.2 years) had baseline TC > 9.3 mmol/L, and overall we found an FH-causing mutation in the LDLR gene in seven (28%) subjects. The detection rate increased to 39% by excluding eight participants with triglyceride levels over 2.3 mmol/L, and reached 75% in those with TC > 10.4 mmol/L. By extrapolation, the detection rate would be ∼25% by including all participants with TC > 8.6 mmol/L (2.5 standard deviations from the mean). Based on the 1/500 FH frequency, 30% of all FH-cases in this cohort would be missed using the 9.3 mmol/L cut-off. Given that an overall detection rate of 25% is considered economically acceptable, these data suggest that a diagnostic TC cut-off of 8.6 mmol/L, rather than 9.3 mmol/L would be clinically useful for FH in the general population.