The variability of SMCHD1 gene in FSHD patients: evidence of new mutations.

In this study, we investigated the sequence of (Structural Maintenance of Chromosomes flexible Hinge Domain containing 1) SMCHD1 gene in a cohort of clinically defined FSHD (facioscapulohumeral muscular dystrophy) patients in order to assess the distribution of SMCHD1 variants, considering the D4Z4 fragment size in terms of repeated units (RUs; short fragment: 1-7 RU, borderline: 8-10RU and normal fragment: >11RU). The analysis of SMCHD1 revealed the presence of 82 variants scattered throughout the introns, exons and 3'untranslated region (3'UTR) of the gene. Among them, 64 were classified as benign polymorphisms and 6 as VUS (variants of uncertain significance). Interestingly, seven pathogenic/likely pathogenic variants were identified in patients carrying a borderline or normal D4Z4 fragment size, namely c.182_183dupGT (p.Q62Vfs*48), c.2129dupC (p.A711Cfs*11), c.3469G>T (p.G1157*), c.5150_5151delAA (p.K1717Rfs*16) and c.1131+2_1131+5delTAAG, c.3010A>T (p.K1004*), c.853G>C (p.G285R). All of them were predicted to disrupt the structure and conformation of SMCHD1, resulting in the loss of GHKL-ATPase and SMC hinge essential domains. These results are consistent with the FSHD symptomatology and the Clinical Severity Score (CSS) of patients. In addition, five variants (c.*1376A>C, rs7238459; c.*1579G>A, rs559994; c.*1397A>G, rs150573037; c.*1631C>T, rs193227855; c.*1889G>C, rs149259359) were identified in the 3'UTR region of SMCHD1, suggesting a possible miRNA-dependent regulatory effect on FSHD-related pathways. The present study highlights the clinical utility of next-generation sequencing (NGS) platforms for the molecular diagnosis of FSHD and the importance of integrating molecular findings and clinical data in order to improve the accuracy of genotype-phenotype correlations.

Facioscapulohumeral muscular dystrophy (FSHD) molecular diagnosis: from traditional technology to the NGS era.

Facioscapulohumeral muscular dystrophy (FSHD) is a genetic neuromuscular disorder which mainly affects the muscles of the face, shoulder, and upper arms. FSHD is generally associated with the contraction of D4Z4 macrosatellite repeats on 4q35 chromosome or mutations in SMCHD1, which are responsible of the toxic expression of DUX4 in muscle tissue. Despite the recent application of NGS techniques in the clinical practice, the molecular diagnosis of FSHD is still performed with dated techniques such as Southern blotting. The diagnosis of FSHD requires therefore specific skills on both modern and less modern analytical protocols. Considering that clinical and molecular diagnosis of FSHD is challenging, it is not surprising that only few laboratories offer a comprehensive characterization of FSHD, which requires the education of professionals on traditional techniques even in the era of NGS. In conclusion, the study of FSHD provides an excellent example of using classical and modern molecular technologies which are equally necessary for the analysis of DNA repetitive traits associated with specific disorders.

Genetic Variants Allegedly Linked to Antisocial Behaviour Are Equally Distributed Across Different Populations.

Human behaviour is determined by a complex interaction of genetic and environmental factors. Several studies have demonstrated different associations between human behaviour and numerous genetic variants. In particular, allelic variants in SLC6A4, MAOA, DRD4, and DRD2 showed statistical associations with major depressive disorder, antisocial behaviour, schizophrenia, and bipolar disorder; BDNF polymorphic variants were associated with depressive, bipolar, and schizophrenia diseases, and TPH2 variants were found both in people with unipolar depression and in children with attention deficit-hyperactivity disorder (ADHD). Independent studies have failed to confirm polymorphic variants associated with criminal and aggressive behaviour. In the present study, a set of genetic variants involved in serotoninergic, dopaminergic, and neurobiological pathways were selected from those previously associated with criminal behaviour. The distribution of these genetic variants was compared across worldwide populations. While data on single polymorphic variants showed differential distribution across populations, these differences failed to be significant when a comprehensive analysis was conducted on the total number of published variants. The lack of reproducibility of the genetic association data published to date, the weakness of statistical associations, the heterogeneity of the phenotype, and the massive influence of the environment on human behaviour do not allow us to consider these genetic variants as undoubtedly associated with antisocial behaviour. Moreover, these data confirm the absence of ethnic predisposition to aggressive and criminal behaviour.

Precision Medicine into Clinical Practice: A Web-Based Tool Enables Real-Time Pharmacogenetic Assessment of Tailored Treatments in Psychiatric Disorders.

The management of neuropsychiatric disorders involves different pharmacological treatments. In order to perform efficacious drug treatments, the metabolism of CYP genes can help to foresee potential drug-drug interactions. The NeuroPGx software is an open-source web-based tool for genotype/diplotype/phenotype interpretation for neuropharmacogenomic purposes. The software provides information about: (i) the genotypes of evaluated SNPs (single nucleotide polymorphisms); (ii) the main diplotypes in CYP genes and corresponding metabolization phenotypes; (iii) the list of neuropsychiatric drugs with recommended dosage adjustment (according to CPIC and DPWG guidelines); (iv) the list of possible (rare) diplotypes and corresponding metabolization phenotypes. The combined application of NeuroPGx software to the OpenArray technology results in an easy, quick, and highly automated device ready to be used in routine clinical practice.

Genetic Counseling and NGS Screening for Recessive LGMD2A Families.

: Genetic counseling applied to limb-girdle muscular dystrophies (LGMDs) can be very challenging due to their clinical and genetic heterogeneity and the availability of different molecular assays. Genetic counseling should therefore be addressed to select the most suitable approach to increase the diagnostic rate and provide an accurate estimation of recurrence risk. This is particularly true for families with a positive history for recessive LGMD, in which the presence of a known pathogenetic mutation segregating within the family may not be enough to exclude the risk of having affected children without exploring the genetic background of phenotypically unaffected partners. In this work, we presented a family with a positive history for LGMD2A (OMIM #253600, also known as calpainopathy) characterized by compound heterozygosity for two CAPN3 mutations. The genetic specialist suggested the segregation analysis of both mutations within the family as a first-level analysis. Sequentially, next-generation sequencing (NGS) analysis was performed in the partners of healthy carriers to provide an accurate recurrence/reproductive risk estimation considering the genetic background of the couple. Finally, this work highlighted the importance of providing a genetic counseling/testing service even in unaffected individuals with a carrier partner. This approach can support genetic counselors in estimating the reproductive/recurrence risk and eventually, suggesting prenatal testing, early diagnosis or other medical surveillance strategies.

NGS Analysis for Molecular Diagnosis of Retinitis Pigmentosa (RP): Detection of a Novel Variant in PRPH2 Gene.

This work describes the application of NGS for molecular diagnosis of RP in a family with a history of severe hypovision. In particular, the proband received a clinical diagnosis of RP on the basis of medical, instrumental examinations and his family history. The proband was subjected to NGS, utilizing a customized panel including 24 genes associated with RP and other retinal dystrophies. The NGS analysis revealed a novel missense variant (c.668T > A, I223N) in PRPH2 gene, which was investigated by segregation and bioinformatic analysis. The variant is located in the D2 loop domain of PRPH2, which is critical for protein activity. Bioinformatic analysis described the c.668T > A as a likely pathogenic variant. Moreover, a 3D model prediction was performed to better characterize the impact of the variant on the protein, reporting a disruption of the α-helical structures. As a result, the variant protein showed a substantially different conformation with respect to the wild-type PRPH2. The identified variant may therefore affect the oligomerization ability of the D2 loop and, ultimately, hamper PRPH2 proper functioning and localization. In conclusion, PRPH2_c.668T > A provided a molecular explanation of RP symptomatology, highlighting the clinical utility of NGS panels to facilitate genotype-phenotype correlations.

Limb-Girdle Muscular Dystrophies (LGMDs): The Clinical Application of NGS Analysis, a Family Case Report.

The diagnosis of LGMD2A (calpainopathy) can be challenging due to genetic heterogeneity and to high similarity with other LGMDs or neuromuscular disorders. In this setting, NGS panels are highly recommended to perform differential diagnosis, identify new causative mutations and enable genotype-phenotype correlations. In this manuscript, the case of a patient affected by LGMD2A is reported, for which the application of a defined custom designed NGS panel allowed to confirm the diagnosis of calpainopathy linked with two heterozygous variants in CAPN3, namely c.550delA and c.1813G>C. The first variant has been extensively described in relation to calpainopathy. The second variant c.1813G>C, instead, is novel and has been predicted to be probably damaging. In addition, NGS analysis on the proband revealed a heterozygous variant (c.550C>T) in the LMNA gene, which is associated with dilated cardiomyopathy. The variant is novel and has been predicted to be deleterious by subsequent bioinformatic analysis. Successively, segregation analysis was performed on family members. Interestingly, none of them showed neuromuscular symptoms but the mother was diagnosed with bradycardia and syncopal episodes and showed a positive family history for cardiomyopathy. The segregation analysis reported that the proband inherited the c.1813G>C (CAPN3) from the father who was a healthy carrier. The mother was positive for c.550delA (CAPN3) and c.550C>T (LMNA), suggesting thereby a possible genetic explanation for her cardiovascular problems. Segregation analysis, therefore, confirmed the inheritance pattern of the variants carried by the proband and highlighted a familiarity for cardiomyopathy which should not be neglected. The NGS analysis was further performed on the partner of the proband, to estimate the reproductive risk of the couple. The partner was negative to NGS screening, suggesting thereby a low risk to have an affected child with calpainopathy and 50% probability to inherit the LMNA variant. This case report showed the clinical utility of the NGS panel in providing accurate LGMD2A diagnosis and identifying complex phenotypes originating from mutations in multiple genes. However, NGS results should always be accomplished by a dedicated genetic counseling, not only to evaluate the recurrence and reproductive risks but also to uncover unexpected findings which can be clinically significant.