Clinical and Genetic Profile of Leber's Hereditary Optic Neuropathy in a Cohort of Patients From a Tertiary Eye Care Center.

PURPOSE: To identify and describe the clinical profile at presentation in patients diagnosed as having Leber's hereditary optic neuropathy with primary and secondary mutations and correlate with treatment. METHODS: A review of electronic medical records from January 2016 to December 2020 for proven cases of Leber's hereditary optic neuropathy was conducted. A total of 157 patients with clinically suspected Leber's hereditary optic neuropathy (143 males and 14 females) underwent genetic testing and 55 were found to have a mutation for Leber's hereditary optic neuropathy. Data of 55 consecutive patients were retrieved and analyzed for their clinical profile, investigations, mutations identified, treatment, and outcome. RESULTS: All 55 patients were male, and the mean age was 23.80 ± 9.90 years (range: 9 to 53 years). The median duration of symptoms before the first physician examination was 6 months. The mean duration between the first hospital visit and genetically proven diagnosis of Leber's hereditary optic neuropathy was 9.03 ± 19.61 months (median: 2 months). More than half of the patients (n = 32; 58.2%) presented with severe to profound vision impairment in the better eye and 72.7% (n = 40) in the worse eye. Bilateral temporal disc pallor was more frequent in 38.2% (n = 21) and 36.4% (n = 20) had bilateral optic atrophy. Primary single mutations were detected in 61.81% (n = 34) and secondary mutations were detected in 38.2% (n = 21). The most common mutation was G11778A. One novel secondary mutation (A13615C) was identified in the cohort. Idebenone was used for treatment in 15 patients, and half of them (n = 8) showed an improvement in vision at 2 to 7 months of follow-up. CONCLUSIONS: The current cohort is the largest study to date in an Indian population that has analyzed the clinical presentations and mutations of Leber's hereditary optic neuropathy. G11778A was the most common primary mutation and several secondary mutations were identified. A delay in referral, inadequate compliance, and cost of care contributed to the outcomes. [J Pediatr Ophthalmol Strabismus. 2022;59(5):344-349.].

Utility of next-generation sequencing in genetic testing and counseling of disorders involving the musculoskeletal system-trends observed from a single genetic unit.

BACKGROUND: Disorders involving the musculoskeletal system are often identified with short stature and a range of orthopedic problems. The clinical and genetic heterogeneity of these diseases along with several characteristic overlaps makes definitive diagnosis difficult for clinicians. Hence, using molecular testing in addition to conventional tests becomes essential for appropriate diagnosis and management. METHODS: Comprehensive clinical examination, detailed pretest and posttest counseling, molecular diagnosis with next-generation sequencing (NGS), genotype-phenotype correlation and Sanger sequencing for targeted variant analysis. RESULTS: This manuscript reports a molecular spectrum of variants in 34 orthopedic cases referred to a single genetic unit attached to a tertiary care hospital. The diagnostic yield of NGS-based tests coupled with genetic counseling and segregation analysis was 79% which included 7 novel variants. In about 53% (i.e. 18/34 cases), molecular testing outcome was actionable since 8 of the 18 underwent prenatal diagnosis, as they were either in their early gestation or had planned a pregnancy subsequent to molecular testing, while ten cases were premaritally/prenatally counseled for the families to take informed decisions as they were in the reproductive age. CONCLUSIONS: The report highlights the importance of NGS-based tests even in a low resource setting as it helps patients, families and healthcare providers in reducing the economic, social and emotional burden of these disorders.

Identification of novel RB1 genetic variants in Retinoblastoma patients and their impact on clinical outcome.

BACKGROUND: Retinoblastoma (RB) is an intraocular childhood cancer develops due to inactivation of RB1 gene. Identification of RB1 genetic variants, correlating and confirming genetic test results with clinical outcomes are crucial for effective RB management. METHODS: Retrospective study of 62 RB patients and 14 family members who underwent genetic testing either by next generation sequencing (NGS) or multiplex ligation-dependent probe amplification (MLPA) or by both for screening RB1 germline mutations present in peripheral blood. Mutational outcomes were correlated with clinical outcomes evaluated over a follow-up period of 12 months. RESULTS: Of the 62 patients, 35 (56%) had bilateral RB and 27 (44%) had unilateral RB. Out of 24 (52%) variants detected by NGS, 9 (37.5%) were novel and 15 (62.5%) were known in 46 probands. Six (18%) gross deletions were detected by MLPA in 34 probands. The mutation detection rate by NGS and MLPA in unilateral cases was 15% (n = 4) and 74% (n = 26) in bilateral cases. In patients with RB1 genetic mutations versus those without, the rate of primary enucleation (7 (12%) vs 18 (44%) eyes; p = .0008) was inversely proportional to tumor recurrence (25 (45%) vs 6 (15%) eyes; p = .002). There was no difference in the rate of globe salvage and metastasis, over a mean follow-up period of 12 months. CONCLUSION: The mutations screening is important for risk assessment in future siblings and offspring of RB patients and most important in unilateral RB for determining if hereditary or not hereditary RB. Its role in predicting clinical outcomes is yet to be determined.

Mitochondrial Genetic Heterogeneity in Leber's Hereditary Optic Neuropathy: Original Study with Meta-Analysis.

Leber's hereditary optic neuropathy (LHON) is a mitochondrial disorder that causes loss of central vision. Three primary variants (m.3460G>A, m.11778G>A, and m.14484T>C) and about 16 secondary variants are responsible for LHON in the majority of the cases. We investigated the complete mitochondrial DNA (mtDNA) sequences of 189 LHON patients and found a total of 54 disease-linked pathogenic variants. The primary variants m.11778G>A and m.14484T>C were accountable for only 14.81% and 2.64% cases, respectively. Patients with these two variants also possessed additional disease-associated variants. Among 156 patients who lacked the three primary variants, 16.02% harboured other LHON-associated variants either alone or in combination with other disease-associated variants. Furthermore, we observed that none of the haplogroups were explicitly associated with LHON. We performed a meta-analysis of m.4216T>C and m.13708G>A and found a significant association of these two variants with the LHON phenotype. Based on this study, we recommend the use of complete mtDNA sequencing to diagnose LHON, as we found disease-associated variants throughout the mitochondrial genome.

Pedigree and BRCA gene analysis in breast cancer patients to identify hereditary breast and ovarian cancer syndrome to prevent morbidity and mortality of disease in Indian population.

Global burden of breast cancer is expected to increase to >2 million new cases every year by 2030 and 10% of these are likely to have hereditary breast and ovarian cancer syndrome. Identifying these individuals by pedigree and BRCA1/2 mutation analyses will enable us to offer targeted mutation testing and appropriate counseling. This study from a tertiary care hospital showed that of the 127 breast cancer patients on treatment during 2014-2015, 24 of them fulfilled the criteria of hereditary breast and ovarian cancer syndrome after detailed verbal autopsy and pedigree analysis, and BRCA1 and 2 next-generation sequencing done after pre-test counseling revealed mutations in 13 cases (54%), these included 9 BRCA1 mutations (69%) and 4 BRCA2 mutation (31%). Subsequent post-test counseling recommended targeted mutation analysis for 64 high-risk members in these 13 families with pathogenic mutations, which will help in surveillance for early detection, appropriate management, and prevention of the disease by decreasing the burden to both family and nation. Results from this preliminary study highlight the importance of genetic counseling, pedigree analysis, and genetic testing. It can be recommended that all oncology units should have a genetic counseling service for providing appropriate support to oncologists, patients, and families to prevent unnecessary testing; however, breast cancer screening program is incomplete without evaluating for hereditary breast and ovarian cancer syndrome.