Targeted exome sequencing in South Indian patients with Familial hypercholesterolemia.

BACKGROUND: Familial hypercholesterolemia (FH) is an autosomal dominant genetic disorder with elevated LDL-C levels which can ultimately lead to premature Coronary Artery Disease (CAD). OBJECTIVES: In presence of limited genetic data on FH in India, the present study was aimed to determine the mutation spectrum in Indian FH patients using a targeted exome sequencing. METHODS: 54 FH cases (31 index cases + 23 extended family members) were categorized according to Dutch Lipid Clinic Network Criteria (DLCNC). Targeted exome sequencing was performed using 23 gene panel associated with lipid metabolism. RESULTS: All subjects showed the presence of family history of CAD, 38(70%) patients had corneal arcus whereas only 06(11%) subjects had xanthomas. As per the DLCNC, definite, probable, possible and unlikely FH were 48%, 30%, 11% and 11% respectively. Mutations were observed in 12 of the 23 gene panel with CETP, APOA5, EPHX2 and SREBP2 genes were identified for the first time in Indian FH patients. All 19 mutations including a novel frame-shift mutation in LDLR gene were reported for the first time in Indian FH patients. These mutations were identified in 28(52%) subjects and interestingly ∼73% of the clinically identified FH patients didn't harbour mutations in FH classical genes (LDLR, ApoB, PCSK9). CONCLUSION: This is the first study in the South Indian FH patients to perform targeted exome sequencing. Absence of mutations in the FH classical genes strongly indicates the polygenic nature of FH, further underscoring the importance of targeted exome sequencing for identifying mutations in genetically diverse Indian population.

Shortcomings on genetic testing of Familial hypercholesterolemia (FH) in India: Can we collaborate to establish Indian FH registry?

Familial hypercholesterolemia (FH) is a common autosomal dominant disorder that affects ∼1 in 250-500 individuals globally. The only prevalence study in India shows FH in 15% of patients with premature CAD in North Indians. There are only 6 genetic studies in India of the total mutations, 32% are LDLR mutations, 4% are ApoB, 2% are PCSK9 mutations and the mutational spectrum for 37% is unknown. This calls for widespread genetic screening which could help identify definite FH patients. European Atherosclerosis Society-Familial Hypercholesterolemia Studies Collaboration (EAS- FHSC) has taken an initiative to develop a worldwide registry of FH. India is also a part of the collaboration and 3 groups from Mumbai, Delhi and Chennai are actively contributing to this registry. We believe this review might help to understand the Indian scenario of FH and investigators across India can contribute in managing FH in India and further help in the detection, diagnosis and treatment.

Screening of PCSK9 and LDLR genetic variants in Familial Hypercholesterolemia (FH) patients in India.

Familial Hypercholesterolemia (FH) is an autosomal, dominant, inherited disorder characterized by severely elevated LDL-cholesterol (LDL-C) levels with high risk for Coronary Artery Disease (CAD). There are limited genetic studies especially on genes other than Low Density Lipoprotein receptor (LDLR) conducted in Indian population. Thus, our aim was to screen the entire Proprotein Convertase Subtilisin/Kexin type 9 gene (PCSK9) gene & hotspot exons 3, 4 and 9 of LDLR gene in FH cases and controls. 50 FH cases were categorized into definite, probable and possible cases according to Dutch Lipid Network Criteria (DLNC) who were gender matched with 50 healthy controls. All 12 exons of PCSK9, and hotspot exons 3, 4 & 9 of LDLR gene were screened through High Resolution Melt (HRM) curve analysis. Enzyme linked immunosorbent assay was performed to measure circulating PCSK9 levels. Total cholesterol and LDL-C were significantly high in all three groups of cases. Total 8 nonpathogenic variants in exon 1, 5, 7 and 9 of the PCSK9 gene were detected. In LDLR gene, 3 known pathogenic and 1 benign variant were found in exon 3 & 4. In FH cases, PCSK9 levels were significantly high compared to controls (P = 0.0001), and were directly correlated to LDL-C (P = 0.0001) and Total Cholesterol (P = 0.0001). Our study is first to screen the entire PCSK9 gene in western part of India. Since no pathogenic variants were identified, it is possible that PCSK9 variants are clinically less relevant. However, 3 known pathogenic variants were found in the LDLR gene. These findings support our understanding of the genetic spectrum of FH in India.

Circulating miRNA-33: a potential biomarker in patients with coronary artery disease.

BACKGROUND: Circulating microRNAs (miRNA) are present in body fluids in stable, cell-free form. Likewise, these miRNAs can be identified in various stages of coronary artery disease (CAD) such as inflammation, endothelial dysfunction, proliferation and atherosclerosis among others. miRNA expression levels can be identified. AIMS AND OBJECTIVES: To determine the expression of circulating miRNAs (miR-126, miR-92, miR-33, miR-145 and miR-155) in CAD patients of Indian origin. MATERIAL AND METHODS: miRNA profiling analysis in blood plasma was performed by quantitative real-time-PCR (qRT-PCR) in 60 angiographically verified subjects including 30 CAD patients and 30 age- and gender-matched controls. Association between the expression of all five circulating miRNAs and clinical characteristics of patients with CAD were analysed using Medcalc statistics. The severity of CAD was assessed using SYNTAX score (SS). RESULTS: Expression of plasma miR-33 increased by 2.9 folds in CAD patients than in control group (p value ≥0.002) also it was found that miR-33 expression levels in mild cases (SS: ≤22) were significantly higher than CAD controls. There was a modest negative correlation between miR-33 and total cholesterol/high density lipoprotein ratio, triglycerides and very low density lipoprotein. CONCLUSION: The study reports a significant association between increased levels of plasma miR-33 and CAD. Thus, plasma miR-33 appears to be a promising non-invasive biomarker, but requires further validation in a large cohort.

Familial Hypercholesterolemia (FH) Awareness Amongst Physicians in Mumbai, India.

BACKGROUND: Familial Hypercholesterolemia (FH) is a common genetic disorder affecting low density lipoprotein cholesterol (LDL-C) metabolism. Prolong exposure to elevated LDL-C results in the development of atherosclerotic lesions and a substantially increased risk of Coronary Artery Disease (CAD). In contrast, early detection and effective treatment of FH can result in a significant improvement in clinical outcomes. Despite these data, FH remains largely underdiagnosed and untreated. OBJECTIVE: To assess the awareness, knowledge, and clinical practices of FH by General Physicians (GPs) in Mumbai. METHODS: Physicians were requested to complete a survey comprising Multiple Choice questions (MCQs) on FH. The questionnaire inquired about; familiarity and awareness of the disorder, clinical description, prevalence, inheritance and their opinions on FH clinical services. RESULTS: Of the 79 GPs surveyed, 31% of them correctly described FH and only 28% knew about its prevalence. 51% perceived themselves to have an above moderate familiarity with this disorder. 46% of them were aware of the risk of cardiovascular disease (CVD) associated with FH. 80% of GPs were unsure or unaware of whether they had FH patients under their care. 50% and 33% of physicians identified statins as monotherapy and statin & ezetimibe as a combination therapy for FH respectively. CONCLUSION AND INTERPRETATION: Immediate attention should be focused on increasing awareness and knowledge about FH in India. Establishment of lipid clinic network will aid in improving care and clinical practices.

Troponin T and Heart Type Fatty Acid Binding Protein (h-Fabp) as Biomarkers in Patients Presenting with Chest Pain.

Acute coronary syndrome (ACS) is a term for a range of clinical signs and symptoms suggestive of myocardial ischemia. It results in functional and structural changes and ultimately releasing protein from injured cardiomyocytes. These cardiac markers play a major role in diagnosis and prognosis of ACS. This study aims to assess the efficacy of heart type fatty acid binding protein (h-FABP) as a marker for ACS along with the routinely used hs-TropT. In our observational study, plasma h-FABP (cut-off 6.32 ng/ml) and routinely done hs-Trop T (cutoff 0.1 and 0.014 ng/ml) were estimated by immunometric laboratory assays in 88 patients with acute chest pain. Based on the clinical and laboratory test findings the patients were grouped into ACS (n = 41) and non-ACS (n = 47). The diagnostic sensitivity, specificity, NPV, PPV and ROC curve at 95 % CI were determined. Sensitivity of hs-TropT (0.1 ng/ml), hs-TropT (0.014 ng/ml) and h-FABP were 53, 86 and 78 % respectively and specificity for the same were 98, 73 and 70 % respectively. Sensitivity, specificity and NPV calculated for a cut-off combination of hs-TropT 0.014 ng/ml and h-FABP was 100, 51 and 100 % respectively. These results were substantiated by ROC analysis. Measurement of plasma h-FABP and hs-TropT together on admission appears to be more precise predictor of ACS rather than either hs-Trop T or h-FABP.