Genotype-phenotype Correlation Analysis Research Articles

Distinct neurodevelopmental and epileptic phenotypes associated with gain- and loss-of-function GABRB2 variants

Variants in GABRB2, encoding the β2 subunit of the γ-aminobutyric acid type A (GABAA) receptor, can result in a diverse range of conditions, ranging from febrile seizures to severe developmental and epileptic encephalopathies. However, the mechanisms underlying the risk of developing milder vs more severe forms of disorder remain unclear. In this study, we conducted a comprehensive genotype-phenotype correlation analysis in a cohort of individuals with GABRB2 variants. Genetic and electroclinical data of 42 individuals harbouring 26 different GABRB2 variants were collected and accompanied by electrophysiological analysis of the effects of the variants on receptor function. Electrophysiological assessments of α1β2γ2 receptors revealed that 25/26 variants caused dysfunction to core receptor properties such as GABA sensitivity. Of these, 17 resulted in gain-of-function (GOF) while eight yielded loss-of-function traits (LOF). Genotype-phenotype correlation analysis revealed that individuals harbouring GOF variants suffered from severe developmental delay/intellectual disability (DD/ID, 74%), movement disorders such as dystonia or dyskinesia (59%), microcephaly (50%) and high risk of early mortality (26%). Conversely, LOF variants were associated with milder disease manifestations. Individuals with these variants typically exhibited fever-triggered seizures (92%), milder degrees of DD/ID (85%), and maintained ambulatory function (85%). Notably, severe movement disorders or microcephaly were not reported in individuals with loss-of-function variants. The data reveals that genetic variants in GABRB2 can lead to both gain and loss-of-function, and this divergence is correlated with distinct disease manifestations. Utilising this information, we constructed a diagnostic flowchart that aids in predicting the pathogenicity of recently identified variants by considering clinical phenotypes. This work was funded by the Australian National Health & Medical Research Council, the Novo Nordisk Foundation and The Lundbeck Foundation.

Compound heterozygous ABCA12 variants identified in a Chinese patient with congenital ichthyosiform erythroderma: Advancing genotype-phenotype correlations and literature review.

Ichthyosis is a common keratotic skin disease with high clinical, etiological and genetic heterogeneity. There are four types of non-syndromic hereditary ichthyoses, among which autosomal recessive congenital ichthyosis (ARCI) is a heterogeneous group of recessive Mendelian disorders. ARCI present with different phenotypes and ABCA12 pathogenic variants have been shown to cause complex ARCI phenotypes, including harlequin ichthyosis (HI), lamellar ichthyosis (LI) and congenital ichthyosiform erythroderma (CIE). A sporadic male patient, clinically diagnosed with CIE, was enrolled in this study. Exome sequencing was combined with Sanger sequencing to confirm the diagnosis and identify the pathogenic variants. In silico predictions were made using multiple software programs, and the identified variants were interpreted using the ACMG guidelines. A review of all literature reported ABCA12 variants was performed to explore genotype-phenotype correlations. Compound heterozygous ABCA12 variants [c.5381+1G>A and c.5485G>C (p.Asp1829His)] (NM_173076) were identified. The two variants were not detected in the public database. c.5381+1G>A is predicted to affect ABCA12 mRNA splicing and Asp1829 is highly conserved among various species. In silico analysis suggested that these two variants were responsible for the phenotype of the patient. Genotype-phenotype correlation analysis showed that biallelic truncation variants and/or exon/amino acid deletions in ABCA12 are the most common causes of HI. Biallelic missense variants are most common in LI and CIE. The compound heterozygous ABCA12 variants caused the CIE phenotype observed in the patient. The spectrum of ABCA12 pathogenic variants were broaden. Genotype-phenotype correlation analysis provided detailed evidence which can be used in future prenatal diagnosis and can inform the need for genetic counselling for patients with ABCA12-related ARCIs.

A novel homozygous missense mutation in the RPE65 gene in an Iranian family with retinitis pigmentosa

Hereditary retinal dystrophies such as retinitis pigmentosa (RP) are genetically and phenotypically heterogeneous and result in total blindness. One of the key genes causing RP is RPE65. In 2017, a gene therapy drug, voretigene neparvovec-rzyl, for RP associated with RPE65 mutations, received Food and Drug Administration approval. So, identification of RPE65 gene mutations in affected patients which may be amenable to genetic treatment is critical. Here, we examine three related Iranian patients with RP which have not been previously described in the population. Whole exome sequencing (WES) using next-generation Illumina sequencing was utilized to identify the disease-causing mutation in the proband. Subsequently, Sanger sequencing was performed to confirm the identified mutation in the patients and their family members. Finally, the possible effect of the reported mutation on the target protein was also evaluated using bioinformatics tools. WES identified a novel homozygous missense mutation c.T170C: p.F57S in exon 3 of the RPE65 gene. Sanger sequencing confirmed the mutation found in the patients and their healthy family members. This mutation segregated with the autosomal recessive inheritance pattern of RP disorder. Furthermore, the pathogenic nature of the identified mutation was confirmed by in silico approaches and genotype-phenotype correlation analysis. Our findings revealed a novel missense mutation c.T170C: p.F57S in the RPE65 gene and could expand the pathogenic mutations spectrum of the RPE65 gene. Additionally, such studies can aid to conduct genetic counseling, prenatal diagnosis, clinical management and even genetic treatment more accurately for all affected patients with RPE65 gene mutations.

Genetic Associations of Primary Angle-Closure Disease

Effects of genetic variants on primary angle-closure disease remained uncertain. To systematically review the associations of common single-nucleotide variants (SNVs) and rare coding variants with primary angle-closure disease, its subtypes (including primary angle-closure glaucoma, primary angle-closure suspect, and primary angle-closure) and progression. Eligible studies from PubMed, Embase, and Web of Science were retrieved up to April 3, 2023. SNV information was extracted from eligible reports and 2 genome-wide association studies summary statistics, UK BioBank and FinnGen. Studies providing analyzable genotype or allele data in a case-control design for primary angle-closure disease association and longitudinal case-only design for primary angle-closure disease progression. PRISMA guidelines were used for literature screening and the Newcastle Ottawa Scale for data quality assessment. Pooled effect size with 95% CIs of SNV associations were calculated using fixed- or random-effect models according to I2 statistics. SNVs reported in 2 or more studies were meta-analyzed to generate pooled odds ratios and P values. Common and rare coding variants from single reports were summarized. Sixty-nine citations were eligible for meta-analysis on overall primary angle-closure disease, involving 206 SNVs in 64 genes or loci. Seventeen SNVs in 15 genes or loci showed associations with primary angle-closure disease, and 15 SNVs in 13 genes or loci showed associations with primary angle-closure glaucoma. Two SNVs, ABCA1 rs2422493 and ZNRF3 rs3178915, were associated only with primary angle-closure disease. Two SNVs, PCMTD1-ST18 rs1015213 and COL11A1 rs3753841, were associated with primary angle-closure suspect, and 1 SNV, MMP9 rs3918249, was associated with primary angle-closure. This systematic review and meta-analysis newly confirmed 7 genes or loci associated with primary angle-closure glaucoma: ATOH7, CALCRL, FBN1, IL6, LOXL1, MMP19, and VAV3. Common and rare coding variants in 16 genes or loci that have been associated with primary angle-closure disease were cataloged. Stratification analysis revealed different primary angle-closure disease-associated genes in different ethnic populations. Only 1 study regarding the genetic association of primary angle-closure glaucoma progression was identified. This study revealed the genetic complexity of primary angle-closure disease, involving common SNVs and rare coding variants in more than 30 genes or loci, with ethnic and phenotypic diversities. Further replication, genotype-phenotype correlation, and pathway analyses are warranted.

Novel indel variation of LTBP4 gene associates with risk of sudden cardiac death in Chinese populations with coronary artery disease

The objective of this study is to investigate whether common genetic variants of the LTBP4 gene are linked to the susceptibility of sudden cardiac death in individuals who have atherosclerotic coronary artery disease (SCD-CAD) in Chinese populations. A total of 208 SCD-CAD cases and 638 controls were included in the analysis, and logistic regression was employed to assess the association between a 4-bp insertion/deletion polymorphism (rs34005443) within LTBP4 and the susceptibility to SCD-CAD among Chinese individuals. Logistic regression analysis demonstrated a notable association between the insertion allele of rs34005443 and an escalated susceptibility to SCD-CAD [odds ratio (OR) = 1.434; 95 % confidence interval:1.14–1.80; P = 1.79 × 10−3]. Genotype-phenotype correlation analysis was performed using Genotype-Tissue expression (GTEx) database and further validated by human myocardium using qPCR. Correlation analysis revealed that LTBP4 expression level was lower in samples with the insertion allele. Furthermore, the dual-luciferase activity assays indicated that rs34005443 may play a regulatory role. Additionally, we predicted 30 transcription factors that are likely to bind to rs34005443 and its highly linked genetic variants via 3DSNP database. Subsequent GO and KEGG analysis indicated that these transcription factors have a significant function in regulating gene expression. Finally, PPI network analysis suggested a tight connection between LTBP4 proteins and TGFβs, highlighting these genes as potential hub genes in the context of SCD-CAD. In summary, our study revealed that rs34005443 might contribute to SCD-CAD susceptibility by regulating LTBP4 expression. These findings revealed that this indel could be a potentially functional marker for molecular diagnosis and risk stratification of SCD-CAD.

Abstract P160: Prevalence of Genetic Dilated Cardiomyopathy: A Systematic Literature Review

Background: Dilated cardiomyopathy (DCM) is a leading cause of heart failure and cardiac transplantation worldwide. Many cases of DCM are due to genetic or idiopathic etiology. Two prominent contributors to genetic DCM (gDCM) are the TTN and MYH7 genes, which encode proteins associated with DCM etiology. Purpose: This study aimed to synthesize the published literature on the global prevalence of adult and pediatric gDCM within the clinical DCM population and the general population. Methods: A systematic review was conducted by searching MEDLINE® and Embase from database inception to 09/19/2022. We included observational studies reporting the prevalence of gDCM within any population; prevalence of TTN and MYH7 mutations were also extracted. Excluded were studies using family history as a proxy for gDCM. Median with interquartile range (IQR) or mean with standard deviation (SD) weighted by sample size (in cases of calculations with <10 studies) were used to summarize the data. Results: Of 2,720 identified abstracts, 57 studies were included in the review. Among the adult or mixed (adults and children) DCM population in any country, median prevalence was 21.0% for overall DCM-related genetic mutations, 11.4% for TTN mutations, and 3.2% for MYH7 mutations ( Table ). The prevalence of pediatric gDCM within the DCM population was similar (weighted mean: 21.3%). Data on prevalence of gDCM within the general population were scarce. Conclusion: This study highlights the variable prevalence of gDCM reported across different populations and settings. The current evidence may underestimate the genetic causes due to technical limitations in genetic testing and limited screening. Accurately determining the prevalence of gDCM is critical for identifying high-risk populations, developing targeted prevention strategies for disease complications, and improving outcomes; epidemiological studies using long-read sequencing techniques and large cohort datasets with genotype-phenotype correlation analyses are needed.

Analysis of pathogenicity and genotype-phenotype correlation of the c.158G>A variant of phenylalanine hydroxylase gene

To explore the pathogenicity and genotype-phenotype correlation of the c.158G>A variant of phenylalanine hydroxylase (PAH) gene among patients with PAH deficiency. Thirty seven children diagnosed with PAH deficiency at the Obstetrics and Gynecology Hospital Affiliated to Nanjing Medical University between July 2016 and June 2021 were selected as the study subjects. Clinical data and results of genetic testing were retrospectively analyzed. Among the 37 patients, mild hyperphenylalaninemia (HPA) was observed in 34 cases, two PAH variants (including c.158G>A), which formed a compound heterozygous mutation genotype, were detected in 33 patients, and the remainder one was found to harbor three PAH variants, including homozygous c.158G>A variants and a heterozygous c.842+2T>A variant. Classical phenylketonuria (PKU) was observed in 3 patients, and three PAH variants were detected in each of them, including two with c.[158G>A,842+2T>A]/c.728G>A and c.[158G>A,842+2T>A]/c.611A>G, respectively, and one with c.[158G>A, c.722G>A]/c.728G>A. The c.158G>A variant has a minimal influence on the PAH activity and is associated with a mild HPA phenotype. The variant should thereby be classified as likely benign. When the c.158G>A variant and other pathogenic variants are arranged in cis position, the ultimate phenotype will be determined by the pathogenicity of other variants.

Best Disease: Global Mutations Review, Genotype-Phenotype Correlation, and Prevalence Analysis in the Israeli Population.

To review all reported disease-causing mutations in BEST1, perform genotype-phenotype correlation, and estimate disease prevalence in the Israeli population. Medical records of patients diagnosed with Best disease and allied diseases from nine Israeli medical centers over the past 20 years were collected, as were clinical data including ocular findings, electrophysiology results, and retina imaging. Mutation detection involved mainly whole exome sequencing and candidate gene analysis. Demographic data were obtained from the Israeli Bureau of Statistics (January 2023). A bibliometric study was also conducted to gather mutation data from online sources. A total of 134 patients were clinically diagnosed with Best disease and related conditions. The estimated prevalence of Best disease was calculated to be 1 in 127,000, with higher rates among Arab Muslims (1 in 76,000) than Jews (1 in 145,000). Genetic causes were identified in 76 individuals (57%), primarily showing autosomal-dominant inheritance due to BEST1 mutations (58 patients). Critical conserved domains were identified consisting of a high percentage of dominant missense mutations, primarily in transmembrane domains and the intracellular region (Ca2+ binding domain) of the BEST1 protein. This study represents the largest cohort of patients with Best disease reported in Israel and globally. The prevalence in Israel is akin to that in Denmark but is lower than that in the United States. Critical conserved domains within the BEST1 protein are pivotal for normal functioning, and even minor missense alterations in these areas lead to a dominant disease manifestation. Genetic testing is indispensable as the gold standard for Best disease diagnosis due to the variable clinical presentation of the disease.

FGD1-related Aarskog–Scott syndrome: Identification of four novel variations and a literature review of clinical and molecular aspects

Patients with Aarskog–Scott syndrome (AAS) have short stature, facial anomalies, skeletal deformities, and genitourinary malformations. FYVE, RhoGEF, and PH domain-containing 1 (FGD1) is the only known causative gene of AAS. However, the diagnosis of AAS remains difficult, and specific treatments are still absent. Patients suspected with AAS were recruited, and clinical information was collected. Genetic testing and functional analysis were carried out for the diagnosis. By literature review, we summarized the clinical and genetic characteristics of FGD1-related AAS and analyzed the genotype–phenotype correlation. Five patients were recruited, and four novel FGD1 variants were identified. The diagnosis of AAS was confirmed by genetic analysis and functional study. Three patients treated with growth hormone showed improved heights during the follow-up period. By literature review, clinical features of AAS patients with FGD1 variants were summarized. Regarding FGD1 variations, substitutions were the most common form, and among them, missense variants were the most frequent. Moreover, we found patients with drastic variants showed higher incidences of foot and genitourinary malformations. Missense variants in DH domain were related to a lower incidence of cryptorchidism. Conclusion: We reported four novel pathogenic FGD1 variations in AAS patients and confirmed the efficacy and safety of growth hormone treatment in FGD1-related AAS patients with growth hormone deficiency. Additionally, our literature review suggested the crucial role of DH domain in FGD1 function.What is Known:• Aarskog–Scott syndrome is a rare genetic disease, and the only known cause is the variant in FGD1 gene. The typical clinical manifestations of AAS include facial, skeletal, and urogenital deformities and short stature.What is New:• We reported four novel FGD1 variants and reported the treatment of growth hormone in FGD1-related AAS patients. Our genotype–phenotype correlation analysis suggested the crucial role of DH domain in FGD1 function.

Analysis of genotype-phenotype correlation in Gaucher disease type 1 using machine learning techniques

Analysis of genotype-phenotype correlation in Gaucher disease type 1 using machine learning techniques

Clinical and Genetic Spectrum in a Large Cohort of Hereditary Spastic Paraplegia.

Next-generation sequencing-based molecular assessment has benefited the diagnosis of hereditary spastic paraplegia (HSP) subtypes. However, the clinical and genetic spectrum of HSP due to large fragment deletions/duplications has yet to be fully defined. We aim to better characterize the clinical phenotypes and genetic features of HSP and to provide new thoughts on diagnosis. Whole-exome sequencing (WES) was performed in patients with clinically suspected HSP, followed by multiple ligation-dependent probe amplification (MLPA) sequentially carried out for those with negative findings in known causative genes. Genotype-phenotype correlation analyses were conducted under specific genotypes. We made a genetic diagnosis in 60% (162/270) of patients, of whom 48.9% (132/270) had 24 various subtypes due to point mutations (SPG4/SPG11/SPG35/SPG7/SPG10/SPG5/SPG3A/SPG2/SPG76/SPG30/SPG6/SPG9A/SPG12/SPG15/SPG17/SPG18/SPG26/SPG49/SPG55/SPG56/SPG57/SPG62/SPG78/SPG80). Thirty patients were found to have causative rearrangements by MLPA (11.1%), among which SPG4 was the most prevalent (73.3%), followed by SPG3A (16.7%), SPG6 (3.3%), SPG7 (3.3%), and SPG11 (3.3%). Clinical analysis showed that some symptoms were often related to specific subtypes, and rearrangement-related SPG3A patients seemingly had later onset. We observed a presumptive anticipation among SPG4 and SPG3A families due to rearrangement. Based on the largest known Asian HSP cohort, including the largest subgroup of rearrangement-related pedigrees, we gain a comprehensive understanding of the clinical and genetic spectrum of HSP. We propose a diagnostic flowchart to sequentially detect the causative genes in practice. Large fragment mutations account for a considerable proportion of HSP, and thus, MLPA screening acts as a beneficial supplement to routine WES. © 2024 International Parkinson and Movement Disorder Society.

Genetic and phenotypic analyses of PRRT2 positive and negative paroxysmal kinesigenic dyskinesia.

Paroxysmal kinesigenic dyskinesia (PKD) is a rare neurological disorder, characterized by attacks of involuntary movements triggered by sudden action. Variants in proline-rich transmembrane protein 2 (PRRT2) are the most common genetic cause of PKD. The objective was to investigate the clinical and genetic characteristics of PKD and to establish genotype-phenotype correlations. We enrolled 219 PKD patients, documented their clinical information and performed PRRT2 screening using Sanger sequencing. Whole exome sequencing was performed on 49 PKD probands without PRRT2 variants. Genotype-phenotype correlation analyses were conducted on the probands. Among 219 PKD patients (99 cases from 39 families and 120 sporadic cases), 16 PRRT2 variants were identified. Nine variants (c.879+4A>G, c.879+5G>A, c.856G>A, c.955G>T, c.884G>C, c.649C>T, c.649dupC, c.649delC and c.696_697delCA) were previously known, while seven were novel (c.367_403del, c.347_348delAA, c.835C>T, c.116dupC, c.837_838insC, c.916_937del and c.902G>A). The mean interval from onset to diagnosis was 7.94 years. Compared to patients without PRRT2 variants, patients with the variants were more likely to have a positive family history, an earlier age of onset and a higher prevalence of falls during pre-treatment attacks (27.14% versus 8.99%, respectively). Patients with truncated PRRT2 variants tend to have bilateral attacks. We identified two transmembrane protein 151A (TMEM151A) variants including a novel variant (c.368G>C) and a reported variant (c.203C>T) in two PRRT2-negative probands with PKD. These findings provide insights on the clinical characteristics, diagnostic timeline and treatment response of PKD patients. PKD patients with truncated PRRT2 variants may tend to have more severe paroxysmal symptoms. This study expands the spectrum of PRRT2 and TMEM151A variants. Carbamazepine and oxcarbazepine are both used as a first-line treatment choice for PKD patients.

Splicing mutations of GSDME cause late-onset non-syndromic hearing loss

Objective:To dentify the genetic and audiological characteristics of families affected by late-onset hearing loss due to GSDMEgene mutations, aiming to explore clinical characteristics and pathogenic mechanisms for providing genetic counseling and intervention guidance. Methods:Six families with late-onset hearing loss from the Chinese Deafness Genome Project were included. Audiological tests, including pure-tone audiometry, acoustic immittance, speech recognition scores, auditory brainstem response, and distortion product otoacoustic emission, were applied to evaluate the hearing levels of patients. Combining with medical history and physical examination to analyze the phenotypic differences between the probands and their family members. Next-generation sequencing was used to identify pathogenic genes in probands, and validations were performed on their relatives by Sanger sequencing. Pathogenicity analysis was performed according to the American College of Medical Genetics and Genomics Guidelines. Meanwhile, the pathogenic mechanisms of GSDME-related hearing loss were explored combining with domestic and international research progress. Results:Among the six families with late-onset hearing loss, a total of 30 individuals performed hearing loss. The onset of hearing loss in these families ranged from 10 to 50 years（mean age: 27.88±9.74 years）. In the study, four splicing mutations of the GSDME were identified, including two novel variants: c. 991－7C>G and c. 1183+1G>T. Significantly, the c. 991－7C>G was a de novo variant. The others were previously reported variants: c. 991-1G>C and c. 991-15_991-13del, the latter was identified in three families. Genotype-phenotype correlation analysis revealed that probands with the c. 991－7C>G and c. 1183+1G>T performed a predominantly high-frequency hearing loss. The three families carrying the same mutation exhibited varying degrees of hearing loss, with an annual rate of hearing deterioration exceeding 0.94 dB HL/year. Furthermore, follow-up of interventions showed that four of six probands received intervention（66.67%）, but the results of intervention varied. Conclusion:The study analyzed six families with late-onset non-syndromic hearing loss linked to GSDME mutations, identifying four splicing variants. Notably, c. 991－7C>G is the first reported de novo variant of GSDME globally. Audiological analysis revealed that the age of onset generally exceeded 10 years,with variable effectiveness of interventions.

Genotype-phenotype correlations of neurofibromatosis type 1: a cross-sectional study from a large Chinese cohort.

Neurofibromatosis type 1 (NF1) is a highly heterogeneous autosomal genetic disorder characterized by a broad spectrum of clinical and molecular manifestations. The correlations between genotype and phenotype in NF1 remain elusive. This study aimed to elucidate genotype-phenotype associations in a large Chinese cohort of NF1 patients. We included NF1 patients from our center who underwent genetic testing for NF1 variants and systemic examination. Genotype-phenotype correlation analyses were performed, focusing on variation types and involved neurofibromin domains. A total of 195 patients were enrolled, comprising 105 males and 90 females, with a median age of 18years. Truncating variants, single amino acid variations, and splicing variants accounted for 139/195 (71.3%), 23/195 (11.8%), and 33/195 (16.9%), respectively. Patients with splicing variants exhibited a significantly higher prevalence of spinal plexiform neurofibromas (spinal PNF) than those with truncating variants (76.4% vs. 51.8%; p = 0.022). Variations affecting the PKC domain were associated with higher rates of cutaneous neurofibromas (CNF) (100% vs. 64.9%, p < 0.001), Lisch nodules (100% vs. 61.2%, p < 0.001), plexiform neurofibromas (PNF) (100% vs. 95.7%, p = 0.009), and psychiatric disorders (11.8% vs. 1.6%, p = 0.042). Patients with mutations in the CSRD had an elevated risk of secondary primary malignancies (11.6% vs. 2.8%, p = 0.015). GRD involvement might enhance the risk of Lisch nodules (76.9% vs. 53.7%, p = 0.044). Variations in the Sec14-PH domain were correlated with a higher rate of CNF (76.8% vs. 58.6%, p = 0.014). Additionally, we found that the p.R1748* variants carry a high risk of malignancy. Our study suggested some novel genotype-phenotype correlations within a Chinese cohort, providing innovative insights into this complex field that may contribute to genetic counseling, risk stratification, and clinical management for the NF1 population.

Exome sequencing-aided precise diagnosis of four families with type I Stickler syndrome.

Stickler syndrome is a multisystemic disorder characterized by ophthalmological and non-ophthalmological abnormalities, frequently misdiagnosed due to high clinical heterogeneity. Stickler syndrome type I (STL1) is predominantly caused by mutations in the COL2A1 gene. Exome sequencing and co-segregation analysis were utilized to scrutinize 35 families with high myopia, and pathogenic mutations were identified. Mutant COL2A1 was overexpressed in cells for mechanistic study. A retrospective genotype-phenotype correlation analysis was further conducted. Two novel pathogenic mutations (c.2895+1G>C and c.3505G>A (p.Val1169Ile)) and two reported mutations (c.1597C>T (p.Arg533*) and c.1693C>T (p.Arg565Cys)) in COL2A1 were identified causing STL1. These mutations are all in the G-X-Y triplet, and c.2895+1G>C contributed to aberrant RNA splicing. COL2A1 mutants tended to form large aggregates in the endoplasmic reticulum (ER) and elevated ER stress. Additionally, mutations c.550G>A (p.Ala184Thr) and c.2806G>A (p.Gly936Ser) in COL2A1 were found in high myopia families, but were likely benign, although c.2806G>A (p.Gly936Ser) is on G-X-Y triplet. Moreover, genotype-phenotype correlation analysis revealed that mutations in exon 2 mainly contribute to retinal detachment, whereas mutations in the collagen alpha-1 chain region of COL2A1 tend to cause non-ophthalmologic symptoms. This study broadens the COL2A1 gene mutation spectrum, provides evidence for ER stress caused by pathogenic COL2A1 mutations and highlights the importance of non-ophthalmological examination in clinical diagnosis of high myopia.

HLA sequencing identifies novel associations and suggests clinical relevance of DPB1*04:01 in ANCA-associated Granulomatosis with polyangiitis

Granulomatosis with polyangiitis (GPA) is a rare systemic autoimmune disease. Major contributions of HLA genes have been reported; however, HLA typing-based diagnosis or risk prediction in GPA has not been established. We have performed a sequencing-based HLA genotyping in a north Indian GPA cohort and controls to identify clinically relevant novel associations. PR3-ANCA-positive 40 GPA patients and 40 healthy controls from north India were recruited for the study. Targeted sequencing of HLA-A,-B,-C,-DRB1,-DQB1, and -DPB1 was performed. Allelic and haplotypic associations were tested. Molecular docking of susceptibility HLA alleles with reported super-antigen epitopes was performed. The association of substituted amino acids located at the antigen-binding domain of HLA was evaluated. Genetic association of five HLA-alleles was identified in GPA. The novel association was identified for C*15:02 (p = 0.04; OR = 0.27(0.09–0.88)). The strongest association was observed for DPB1*04:01 (p < 0.0001; OR = 6.2(3.08–11.71)), previously reported in European studies. 35 of 40 GPA subjects had at least one DPB1*04:01 allele, and its significant risk was previously not reported from the Indian population. Significantly associated haplotypes DRB1*03:01–DQB1*02:01–DPB1*04:01 (p = 0.02; OR = 3.46(1.11–12.75)) and DRB1*07:01–DQB1*02:02–DPB1*04:01 (p = 0.04; OR = 3.35(0.95–14.84)) were the most frequent in GPA patients. Ranging from 89 % to 100 % of GPA patients with organ involvement can be explained by at least one DPB1*04:01 allele. A strong interaction between the HLA and three epitopes of the reported super antigen TSST-1 of Staphylococcus aureus was confirmed. Our study highlighted the potential applicability of HLA typing for screening and diagnosis of GPA. A large multi-centric study and genotype-phenotype correlation analysis among GPA patients will enable the establishment of HLA-typing based GPA diagnosis.

Genotipe-phenotype correlation in alpk3 null variants. an extended analysis

Abstract Introduction ALPK3 null variants (ALPK3nv) in simple heterozygosis represent an established and emerging genetic cause for hypertrophic cardiomyopathy. Some studies have indicated that this genetic substrate would be associated with a disease of late-onset disease and incomplete penetrance. Purpose To perform an extended genotype-phenotype correlation analysis with respect to simple heterozygous ALPK3nv carriers, focusing on age at diagnosis, maximum wall thickness and survival analysis, performed on the largest available released cohort to date. Methods ALPK3 gene was included in an extended NGS panel in 16,780 probands from a reference multicentric genetic laboratory, of whom 6,505 were referred with a HCM phenotype. We collected a composite cohort of ALPK3nv (considering frameshift, nonsense and splice-site predicted frameshift variants), including index and familial cases referred to this laboratory, but also cases reported in the literature. Phenotypic behavior was analyzed, mainly considering age at diagnosis, maximum LV wall thickness, and a composite of events (heart failure and arrhythmia-related endpoints). Results A heterozygous ALPK3 null variant was identified in 110 probands out of 6,505 index cases diagnosed with HCM in our center (1.7% of HCM cases). For genotype-phenotype analysis, in total 189 heterozygous carriers were included, considering relatives and cases from the literature; 21 carriers had biallelic involvement (were homozygous or compound heterozygous for two ALPK3Knv). Among ALPK3nv heterozygous carriers, mean age at diagnosis was 53.4 (±15.2) years; mean left ventricular thickness was 17.7 (±4.9) mm, and morphological profile was mainly apical (42%) and/or concentric (26%). Males tended to be diagnosed at an earlier age than females (median age of diagnosis was 56 vs 71 years, respectively, p &amp;lt;0.01). Five events were observed in this group (four males and one female) all of them related to heart failure, and occur in carriers older than 45 years. The clinical profile was drastically different in cases with biallelic involvement, with a mean age at diagnosis of 22.2±9.3, mean LV wall thickness of 24 mm (±8.6), with LV dysfunction observed in 25%. Nine events were observed in this group, also mostly associated with HF (70%). Conclusions ALPK3 null variants in simple heterozygosis can explain 1.7% of HCM. They were associated with late-onset disease, especially in females, predominance of apical and/or concentric forms, and a phenotype that was not particularly severe, both morphologically and in terms of survival.

Atypical features in two adult patients with Cockayne syndrome and analysis of genotype-phenotype correlation.

Atypical features in two adult patients with Cockayne syndrome and analysis of genotype-phenotype correlation.

Remote modulation of WWOX by an intronic variant associated with survival of Chinese gastric cancer patients.

The protein WWOX was reported to be involved in cancer progression via interaction with mTOR and DNA repair pathway. We previously reported noteworthy association of some single nucleotide polymorphisms (SNPs) in mTOR and DNA repair pathways with gastric cancer (GCa) patients' survival. We hypothesized that genetic variants in WWOX gene could predict the survival of GCa patients. By extracting WWOX genetic variants from our ongoing genome-wide association study including 796 GCa patients from an Eastern Chinese population, we identified 51 out of 1913 SNPs to be significantly associated with survival of GCa patients, which passed the false positive probability tests. In particular, the intronic variant rs9922483, a G>T change, was associated with 21% increased death risk for GCa patients (HR = 1.21, 95% CI = 1.04-1.42, P = .015). This locus was predicted to be involved in potential enhancer by bioinformatics analysis. Genotype-phenotype correlation analysis revealed decreased expression of WWOX by rs9922483 G>T change. Mechanistically, rs9922483 locus may exhibits long-range interaction with WWOX promoter, and the G>T change inhibited the transcriptional activity driven by WWOX promoter in luciferase reporter system. Especially, the G>T change had an allele-specific negative effect on NR3C1 binding, and NR3C1 promoted the expression of WWOX in GCa cells. Further functional analysis indicated an increase in proliferation, migration and invasion of GCa cells by knockdown of WWOX. In conclusion, WWOX genetic variants may modulate survival of Chinese GCa patients by exerting remote regulatory effect on WWOX expression. Our results highlight the cis-regulatory effect of genetic variants on genes and survival modulation for GCa patients.

An integrative analysis of genotype-phenotype correlation in Charcot Marie Tooth type 2A disease with MFN2 variants: A case and systematic review

Dominant genetic variants in the mitofusin 2 (MFN2) gene lead to Charcot-Marie-Tooth type 2A (CMT2A), a neurodegenerative disease caused by genetic defects that directly damage axons. In this study, we reported a proband with a pathogenic variant in the GTPase domain of MFN2, c.494A > G (p.His165Arg). To date, at least 184 distinct MFN2 variants identified in 944 independent probands have been reported in 131 references. However, the field of medical genetics has long been challenged by how genetic variation in the MFN2 gene is associated with disease phenotypes. Here, by collating the MFN2 variant data and patient clinical information from Leiden Open Variant Database 3.0, NCBI clinvar database, and available related references in PubMed, we determined the mutation frequency, age of onset, sex ratio, and geographical distribution. Furthermore, the results of an analysis examining the relationship between variants and phenotypes from multiple genetic perspectives indicated that insertion and deletions (indels), copy number variants (CNVs), duplication variants, and nonsense mutations in single nucleotide variants (SNVs) tend to be pathogenic, and the results emphasized the importance of the GTPase domain to the structure and function of MFN2. Overall, three reliable classification methods of MFN2 genotype-phenotype associations provide insights into the prediction of CMT2A disease severity. Of course, there are still many MFN2 variants that have not been given clear clinical significance, which requires clinicians to make more accurate clinical diagnoses.