Molecular spectrum, family screening and genetic counselling of Spinocerebellar Ataxia (SCA) cases in an Indian scenario.

Spinocerebellar Ataxia (SCA) is a heterogeneous adult-onset disorder with an autosomal dominant inheritance pattern mainly caused by triplet repeat expansions. Clinical diagnosis of SCA is based on phenotypic features followed by confirmation through molecular diagnosis. To identify status of repeat range in Indian SCA cases and provide extended family screening, we enrolled 70 clinical SCA suspects. For molecular diagnosis, multiplex PCR (M-PCR) was used for common Indian SCA subtypes 1, 2, 3, 6, 7, 10, 12 and 17. TP-PCR was further used in SCA2, 7 and 10 to identify larger expansions. Eighteen out of 70 SCA suspects (25%) were found to be positive for various SCA subtypes- (5 SCA1 (28%), 6 SAC2 (34%), 2 SCA3 (12%), 3 SCA7 (16%) and one each for SCA6 (1%) and SCA17 (1%) subtypes). Genetic counselling and extended family screening were offered to all positive cases and yielded additional nine cases. We have established M-PCR and TP-PCR to detect the CAG repeat expansion in SCA suspects. This method can confirm SCA subtypes in a reliable, rapid and cost-effective way. Genetic characterization of SCA-related genes has great clinical relevance, as it could provide additional information and guidance to clinicians and family members regarding prognosis.

Defining the role of FMR1 gene in unexplained recurrent spontaneous abortion.

INTRODUCTION: Recurrent spontaneous abortion is a multifactorial disorder and till date, various factors have been attributed in its pathogenesis. Still, approximately 50% of RSA cases remain unexplained. Premutation (PM) expanded allele of fragile-X mental retardation 1 (FMR1) gene is known to contribute to ovarian dysfunction in 20% of the cases. Recently, the link between expanded FMR1 allele and recurrent miscarriages has been reported. METHOD: In the present prospective case-control study, we have investigated the status of CGG repeat size at 5'UTR of the FMR1 gene in women with unexplained RSA in comparison to age-matched healthy control women (n = 100 each). The genomic DNA from these samples was subjected to molecular analysis for characterization of CGG repeat size and composition at FMR1 gene RESULTS: As compared to the control women, the RSA women cohort had a higher frequency of carriers with alleles in gray zone (GZ) and expanded PM range, i.e., 2% (2/100) versus 5% (5/100), respectively. Also, the RSA cohort had a significantly higher number of normal alleles with ≥ 35 CGG repeats (24 out of 200 alleles) as compared to control cohort (8 out of 200 alleles). The number of larger FMR1 alleles with pure CGG repeat tract was found to be significantly higher (P = 0.0063) in the RSA cohort (15 out of 200 alleles) as compared to that in control cohort (3 out of 200 alleles). CONCLUSION: Henceforth, the CGG expanded uninterrupted FMR1 allele might be associated with recurrent abortions and may help to explain many of these unexplained cases.

Connecting links between genetic factors defining ovarian reserve and recurrent miscarriages.

PURPOSE: Approximately 1-2% of the women faces three or more successive spontaneous miscarriages termed as recurrent miscarriage (RM). Many clinical factors have been attributed so far to be the potential risk factors in RM, including uterine anomalies, antiphospholipid syndrome, endocrinological abnormalities, chromosomal abnormalities, and infections. However, in spite of extensive studies, reviews, and array of causes known to be associated with RM, about 50% cases encountered by treating physicians remains unknown. The aims of this study were to evaluate recent publications and to explore oocyte-specific genetic factors that may have role in incidence of recurrent miscarriages. METHOD: Recent studies have identified common molecular factors contributing both in establishment of ovarian reserve and in early embryonic development. Also, studies have pointed out the relationship between the age-associated depletion of OR and increase in the risk of miscarriages, thus suggestive of an interacting biology. Here, we have gathered literature evidences in establishing connecting links between genetic factors associated with age induced or pathological OR depletion and idiopathic RM, which are the two extreme ends of female reproductive pathology. CONCLUSION: In light of connecting etiological link between infertility and RM as reviewed in this study, interrogating the oocyte-specific genes with suspected roles in reproductive biology, in cases of unexplained RM, may open new possibilities in widening our understanding of RM pathophysiology.

Molecular screening of intellectually disabled patients and those with premature ovarian failure for CGG repeat expansion at FMR1 locus: Implication of combined triplet repeat primed polymerase chain reaction and methylation-specific polymerase chain reaction analysis.

BACKGROUND: Fragile X syndrome (FXS) is also a leading cause of intellectual disability along with Down's syndrome. It is caused by the expansion of CGG triplet repeat at 5' untranslated region of the fragile X mental retardation 1 (FMR1) gene. Since the prevalence rate is quite high in the general population, molecular diagnosis is important to establish the cause and the prenatal diagnosis. At present, there are a number of methods available with their own merits and demerits. AIM AND METHODS: Molecular screening of intellectually disabled patients and those with premature ovarian failure with combined triplet repeat primed polymerase chain reaction (TP-PCR) and methylation-specific polymerase chain reaction (MS-PCR) for establishing the diagnosis of FXS. RESULTS: The specificity of the method has been validated with archived previously genotyped samples, facilitating the application of this method in the screening procedure. The combined TP-PCR and MS-PCR approach identified six (10%) of the intellectually disabled cases as full mutation positive, one (4%) of the premature ovarian failure cases as premutation positive, and one (out of two) of the prenatal samples as premutation positive. CONCLUSION: The present study concludes that a combined usage of TP-PCR and MS-PCR will be a useful alternative approach to diagnose patients suffering from fragile X syndrome.

Maternal Risk Factors Triggering Congenital Heart Defects in Down Syndrome: A Case-Control Study.

OBJECTIVES: Maternal MTHFR and MTRR polymorphisms as a risk of CHD in DS fetus were studied along with maternal folic acid supplementation, which could influence the folate metabolism along with other risk factors. MATERIAL AND METHODS: A case-control study comprising of mothers of DS with and without CHD along with controls were recruited from a tertiary care center since 2018-2019. Genomic DNA was isolated followed by PCR-RFLP. RESULTS: Mothers with age ≥35 years and having history of miscarriages have a higher risk of giving birth to DS with CHD (n = 35% and 42%, respectively). Mothers who carried the MTHFR 677CT/TT and MTRR 524CT/TT genotypes combination in the folic acid nonusers group during pregnancies had six-fold (OR = 6.909, p-value = 0.027; 95% CI-1.23 ± 38.51) and four-fold (OR = 4.75, p-value = 0.040; 95% CI-1.067 ± 21.44) increased odds of having a DS child with CHD, respectively, as compared to folic acid users. CONCLUSION: Maternal age, folic acid supplementation, and previous history of miscarriages is involved in the etiology of CHD in DS fetus in Indian population. Maternal MTHFR and MTRR polymorphisms are also involved in the occurrence of CHD and DS in Indian population when controlling for periconceptional folic acid supplementation. LIMITATIONS: Single-Centered Study.

Brain exosomes as minuscule information hub for Autism Spectrum Disorder.

INTRODUCTION: Autism spectrum disorder (ASD) is a neurodevelopmental disorder initiating in the first three years of life. Early initiation of management therapies can significantly improve the health and quality of life of ASD subjects. Thus, indicating the need for suitable biomarkers for the early identification of ASD. Various biological domains were investigated in the quest for reliable biomarkers. However, most biomarkers are in the preliminary stage, and clinical validation is yet to be defined. Exosome based research gained momentum in various Central Nervous System disorders for biomarker identification. However, the utility and prospect of exosomes in ASD is still underexplored. AREAS COVERED: In the present review, we summarized the biomarker discovery current status and the future of brain-specific exosomes in understanding pathophysiology and its potential as a biomarker. The studies reviewed herein were identified via systematic search (dated: June 2021) of PubMed using variations related to autism (ASD OR autism OR Autism spectrum disorder) AND exosomes AND/OR biomarkers. EXPERT OPINION: As exosomess are highly relevant in brain disorders like ASD, direct access to brain tissue for molecular assessment is ethically impossible. Thus investigating the brain-derived exosomes would undoubtedly answer many unsolved aspects of the pathogenesis and provide reliable biomarkers.

Investigation of LOY in Prostate, Pancreatic, and Colorectal Cancers in males: A case-control study.

Background: LOY is associated with ageing and increase the incidence of cancers. Aims: To elucidate the role of LOY in various cancer types, namely, prostate (PRT), pancreatic (PC), and colorectal (CRC) cancers in males. Material and Methods: Fifty CRC patients [mean age = 44.58±11.2 years], fifty PRT [mean age= 60.48± 17.07 years] and fifty PC [mean age = 48.74 ±16.45 years] along with 100 healthy controls [mean age= 54.06 ±15.04 years] were recruited. DNA was isolated from peripheral blood and was subjected to multiplex QF-PCR. The Y/X ratio was calculated from the peak height. Results: The mean Y/X ratio was lower in all patients with cancers (0.875333± 0.086; p value˂ 0.0001) than in controls (1.11 ± 0.071), as well as, in CRC (0.926±0.192; p value˂0.0001), PC (0.85 ± 0.0311; p value˂0.0001) and PRT (0.85±0.122; p value˂0.0001) when calculated separately. Multivariate logistic regression analysis was used to analyze the strength of the presence of cancer prediction using the percentage of LOY and age showed that LOY (p= 0.001) is a better predictor of cancer presence than age (p= 0.359). Conclusion: LOY in blood could be a predictive biomarker in the carcinogenesis of males.

Fragile X molecular investigation and genetic counseling of intellectual disability/developmental delay patients in an Indian scenario.

Background: Fragile X Syndrome (FXS), the most common cause of inherited intellectual disability (ID), is caused by a CGG repeat expansion (full mutation (FM), >200 CGG) at the Fragile X Mental Retardation 1 (FMR1) gene. Early identification of FXS has prognostic significance for affected individuals due to early initiation of interventions. Genetic counseling and family screening can aid parents and at-risk asymptomatic carriers (premutation (PM), 55-200 CGG) in taking proper reproductive decisions. Methodology: The present study utilizes Triplet Primed-Polymerase Chain Reaction (TP-PCR) methodology for detecting the repeat expansion at FMR1 gene in 233 Indian intellectual disability/developmental delay (ID/DD) patients. Results: We have identified 18/233 (7.7%) FXS positive cases. Early diagnosis was made in 66.7% cases (<10 years). Extended family screening in 14 affected individuals identified 9 additional FM cases (7 males and 2 females) and 23 carrier PM females, which otherwise could have been missed. Four prenatal diagnoses were also performed, leading to the identification of 1 PM and 1 FM carrier fetus. Conclusion: A high frequency (7.7%) of FXS among Indian ID/DD subjects obtained in this study depicted the need for more professional recommendations concerning prompt referral for genetic testing, and increased exposure to information about FXS to pediatricians.

Molecular Characterization of FMR1 Gene by TP-PCR in Women of Reproductive Age and Women with Premature Ovarian Insufficiency.

BACKGROUND: Fragile X syndrome is caused by CGG repeat expansion mutation in the FMR1 gene. Normal alleles have 5-44 CGG repeats with AGG interruptions. The expanded gray zone (GZ) (45-54 repeats) and premutation (PM) (55-200 repeats) alleles are often uninterrupted and are unstably inherited in subsequent generations. The prevalence of PM and GZ carriers is high in the female population, at 1/66 and 1/113, respectively, and PM is associated with fertility problems in 20% of cases. OBJECTIVE: Our objective was to molecularly characterize CGG repeats and AGG interruption sequences in the FMR1 gene in women of reproductive age and in women with premature ovarian insufficiency (POI). MATERIALS AND METHODS: We conducted molecular analysis of the FMR1 gene from 300 women of reproductive age and 140 women with POI using triplet primed-polymerase chain reaction. This enabled us to identify carriers and to document CGG repeat size and the AGG interruption pattern. RESULTS: In women of reproductive age, 1.7% were GZ carriers and 0.3% were PM carriers; in women with POI, 3.6% were GZ carriers and 2.14% were PM carriers. The frequency of GZ and PM carriers did not significantly differ between the cohorts (Fisher's exact test: p < 2.23 for GZ vs. control and p < 0.101 for PM vs. control). Carriers received genetic counselling; family screening identified an additional seven carriers. CONCLUSION: We documented preliminary data on the prevalence of GZ and PM carriers among the studied cohorts. The identification of PM carriers among women with POI serves a dual purpose of recognizing a cause for ovarian dysfunction and enabling genetic counselling, which will help carriers when making reproductive decisions.