CFTR mutations and phenotypic correlations in people with cystic fibrosis: a retrospective study from a single centre in south India.

Background: Emerging data reveal higher-than-expected prevalence of cystic fibrosis (CF) among non-European populations worldwide including in the Indian subcontinent. Systematic analyses of the CFTR mutation profile, and genotype-phenotype correlations among people with CF from south, east, or northeast India have not been reported before. We wanted to identify CFTR mutations in people with CF, and highlight novel variants, selective phenotypic correlations, and regional variances within India. Methods: A retrospective study was conducted at Christian Medical College, Vellore, India (single tertiary referral hospital) from September 2010 to August 2022, involving 120 people with CF from (i) four south Indian states (Tamil Nadu, Andhra Pradesh, Kerala, Karnataka), (ii) in and nearby regions of West Bengal, India and (iii) Bangladesh. Comprehensive CFTR mutation analyses were done by Next-Generation Sequencing, and variants were categorized per American College of Medical Genetics guidelines and compared with validated Locus-specific databases. Demographic characteristics, mutation profile, novel mutations, selective phenotype correlations, and regional variances were assessed. Findings: In 120 people with CF, 55 CFTR variants were identified, including six novel variants. F508del was the predominant mutation, yet with a lower allele frequency than reported among European populations (27% versus 70%). Phenotypic correlations suggested high mutational pathogenicity causing severe multi-organ morbidity, and death in 27%. Milder variants associated with pancreatic sufficiency were also evident in 23% of people with CF. Statistically significant regional variances were noted in genotype frequency, and clinical phenotype among people with CF from the two regions. Hotspot exons and introns that could potentially help create targeted mutation panels were identified. Interpretation: The identification of 55 different CFTR variants among 120 people with CF describes the diversity of mutations noted in India, while also revealing the challenges that providers may encounter in timely diagnosis and treatment of CF. However, these single-centre data have specific limitations and cannot be generalised to all people with CF from India or to those of non-European origin. Our data on regional CFTR mutations contribute to the emerging national registry on CF epidemiology in India, help formulate diagnostic and newborn screening algorithms, help optimise clinical care, and highlight urgency to improve access to life-changing modulator therapy. Funding: Cystic Fibrosis Foundation, USA (towards the CF-India Demonstration Project) and Christian Medical College, Vellore, India.

The BRCA mutation spectrum among breast and ovarian cancers in India: highlighting the need to screen BRCA1 185delAG among South Indians.

Mutations in BRCA1 and BRCA2 significantly elevate the risk of developing breast and ovarian cancer. Limited data exists regarding the prevalence of BRCA mutations, and optimal, cost-effective testing strategies in developing countries like India. This study aimed to evaluate the utility of a Next Generation Sequencing (NGS) panel for BRCA1/2 mutation testing among women diagnosed with, or at risk of developing hereditary breast and ovarian cancers. We also aimed to identify population specific BRCA1/2 mutation hotspots, to enable the development of more affordable testing strategies. We identified 921 patients with breast and ovarian cancer who underwent mutation testing. The target enrichment was followed by targeted NGS in 772 patients and an allele-specific PCR (ASPCR) based genotyping for BRCA1:c.68_69delAG (or 185delAG), was carried out in 149 patients. We identified 188 (20.4%) patients with BRCA1/2 variants: 118 (62.8%) with pathogenic/likely pathogenic and 70 (37.2%) with VUS. The 185delAG was identified as a recurrent mutation in the Southern Indian population, accounting for 24.6% of the pathogenic variants. In addition, a family history of breast, ovary, pancreas, or prostate (BOPP) cancer was found to be associated with an increased risk of identifying a deleterious BRCA1/2 variant [OR = 2.11 (95% CI 1.45-3.07) p ≤ 0.001]. These results suggest that Targeted NGS is a sensitive and specific strategy for BRCA testing. For Southern Indian patients, a two-tiered approach can be considered: Initial screening with ASPCR for BRCA1 185delAG followed by NGS for those testing negative. Expanding the gene panel and identifying other population-specific mutation hot spots is a promising area with potential for improvements in testing and treatment strategies.

Focused panel sequencing points to genetic predisposition in non-cirrhotic intrahepatic portal hypertension patients in India.

OBJECTIVE: Non-cirrhotic intrahepatic portal hypertension (NCIPH), a portal microangiopathy affecting small portal vein radicles, is a disease of Indian sub-continent. NCIPH appears to be a complex disease with interactions between inherited and acquired factors, though the exact pathophysiological mechanism is unknown. We aimed at investigating the genetic variants that might contribute to susceptibility to NCIPH. METHODS: In this case-control study, we analyzed genes associated with microangiopathy-VWF-ADAMTS13 (von Willebrand factor and its cleavase enzyme - a disintegrin and matrix metalloprotease with thrombospondin type-1 motifs member 13) and alternative complement system vitamin B12 metabolism and with familial NCIPH. RESULT: Eighty-four Indian patients with liver biopsy-proven NCIPH (cases) and 103 healthy controls (matched for residential region of India) were included in the study. Targeted next-generation sequencing (NGS) panel, comprising 11 genes of interest, was done on 54 cases. Genotyping of selected variants was performed in 84 cases and 103 healthy controls. We identified variants in MBL2, CD46 and VWF genes either associated or predisposing to NCIPH. We also identified a single case with a novel compound heterozygous mutation in MBL2 gene, possibly contributing to development of NCIPH. CONCLUSION: In this first of a kind comprehensive gene panel study, multiple variants of significance have been noted, especially in ADAMTS13-VWF and complement pathways in NCIPH patients in India. Functional significance of these variants needs to be further studied.

Diabetes Mellitus With Renal and Müllerian Anomalies.

OBJECTIVE: Maturity-onset diabetes of the young (MODY) type 5 is caused by an autosomal dominant mutation in the HNF1B gene. Our objective was to report a case of a young girl with bicornuate uterus and recurrent renal stones with diabetes mellitus (DM) without a family history that was diagnosed to be MODY 5. CASE REPORT: A 12-year-old girl presented with recurrent renal stones that were managed with lithotripsy and double-J stenting at various time points. At the age of 14 years, she was found to have a bicornuate uterus with an absent cervix and vagina. She was diagnosed with DM at the age of 16 years without a preceding history of osmotic symptoms or steatorrhea. Although there was no family history of young-onset diabetes, given her long-standing history of müllerian abnormalities, renal cysts, and pancreatic hypotrophy, she was evaluated for MODY. Using the next-generation sequencing, she was found to be positive for a reported HNF1B gene pathogenic mutation c.494G>A (p.Arg165His), confirming a diagnosis of MODY 5. DISCUSSION: There is a significant overlap in clinical criteria for type 2 DM and MODY in the Asian Indian population. The HNF1B gene mutation is difficult to diagnose as none of the clinical manifestations are pathognomonic and many lack a family history of DM. Diagnostic algorithms with specific clinical and biochemical criteria along with pancreatic imaging can help in case detection and direct toward particular genetic mutation analysis. CONCLUSION: We suggest that genetic testing be offered to patients with otherwise unexplained DM and such genitourinary anomalies.

Sirolimus therapy for congenital hyperinsulinism in an infant with a novel homozygous KCNJ11 mutation.

BACKGROUND: Congenital hyperinsulinism results in refractory hypoglycemia. If a therapy with diazoxide has been unresponsive this has been treated by subtotal pancreatectomy in the past. This therapeutic option poses an increased risk of developing diabetes at a later stage. There have been a few case reports on the use of sirolimus in such situations in the recent past. CASE PRESENTATION: Our patient was started on sirolimus very early, on day 29 of life and at the age of 14 months is doing well on sirolimus therapy. His growth and development have been good and he has not had any major complications so far. Genetic testing showed a novel KCNJ11 homozygous mutation on next generation sequencing and the parents were heterozygous carriers. CONCLUSIONS: We report the successful use of sirolimus in the management of diazoxide unresponsive congenital hyperinsulinism with diffuse pancreatic involvement. We believe this is the youngest patient to be initiated on sirolimus so far.

ADAMTS13 missense variants associated with defective activity and secretion of ADAMTS13 in a patient with non-cirrhotic portal hypertension.

BACKGROUND: Non-cirrhotic intrahepatic portal hypertension (NCIPH) is characterized by thrombotic microangiopathy of the portal venous system, low ADAMTS13 (a disintegrin-like and metalloproteinase with thrombospondin type 1 motifs-13), and high vWF (von Willebrand factor) levels. This study aimed to screen for ADAMTS13 mutations, focusing on the CUB domain, in these patients. METHODS: Prospectively recruited NCIPH patients and healthy volunteers underwent tests for plasma vWF-ADAMTS13 balance. Sanger sequencing of the CUB domain of ADAMTS13 was done in a subset of the NCIPH patients, and the detected mutation was screened for in all the study participants. Next-generation sequencing of clinically relevant exome and liver immunostaining for ADAMTS13 was done in patients with detected ADAMTS13 mutation. RESULTS: Plasma vWF-ADAMTS13 balance was significantly altered in 24 NCIPH patients (Child's class A:23, B:1) as compared to 22 controls. On initial sequencing of the CUB domain (17 cases and 3 controls), one NCIPH patient showed a rare missense variant (SNV) at position c.3829C >T resulting in p.R1277W (rs14045669). Subsequent RFLP analysis targeted to the R1277W variant did not detect this in any other NCIPH patient, nor in any of the 22 controls. The NCIPH patient with the R1277W variant had severe ADAMTS13 deficiency, consistently high vWF, other missense SNVs in ADAMTS13, vWF, and complement genes. Immunostaining of his liver biopsy revealed globules of ADAMTS13 within stellate cells. CONCLUSIONS: We report missense variants in ADAMTS13, vWF, and complement genes in a patient with NCIPH who had decreased secretion and activity of ADAMTS13 protein. Further studies are needed in NCIPH patients in this regard.

Association of genetic variants with response to iron supplements in pregnancy.

The incidence of iron deficiency anemia in pregnancy is high in India where iron supplementation is a regular practice. The response to oral iron is influenced by several factors such as age, body mass index, gravida, socioeconomic status, food, vitamin deficiency and compliance to supplements. The major challenge is to understand the various modulators of iron status in this high-risk group so that we can improve the diagnosis and the management of these patients. The current study was designed to evaluate the iron status during pregnancy and to identify factors which might be influencing their response to oral iron. We investigated a total of 181 pregnant women with anemia (Hb < 11 g/dl) and evaluated the impact of probable factors on anemia and their iron status. Assessment of the response was based on hemoglobin and serum ferritin or transferrin saturation level after 8 and 20 weeks of iron supplementation. Socioeconomic, clinical, hematological, biochemical and genetic factors were all evaluated. Molecular analysis revealed that HFE variant allele (G) (rs1799945) was significantly associated with an adequate response to iron supplementation. We identified five subjects with a sustained poor response, and targeted re-sequencing of eleven iron-related genes was performed in them. We have identified seven novel variants in them, and in silico analysis suggested that these variants may have an iron regulatory effect. Taken together, our findings underscore the association of genetic variants with response to supplements in pregnancy, and they can be extended to other diseases where anemia and iron deficiency coexist.