Identification of a novel GNAS mutation in a family with pseudohypoparathyroidism type 1A.

BACKGROUND: Pseudohypoparathyroidism (PHP) is caused by loss-of-function mutations at the GNAS gene (as in the PHP type 1A; PHP1A), de novo or inherited at heterozygous state, or by epigenetic alterations at the GNAS locus (as in the PHP1B). The condition of PHP refers to a heterogeneous group of disorders that share common clinical and biological features of PTH resistance. Manifestations related to resistance to other hormones are also reported in many patients with PHP, in association with the phenotypic picture of Albright hereditary osteodystrophy characterized by short stature, round facies, subcutaneous ossifications, brachydactyly, mental retardation and, in some subtypes, obesity. The purpose of our study is to report a new mutation in the GNAS gene and to describe the significant phenotypic variability of three sisters with PHP1A bearing the same mutation. CASE PRESENTATION: We describe the cases of three sisters with PHP1A bearing the same mutation but characterized by a significantly different phenotypic picture at onset and during follow-up in terms of clinical features, auxological pattern and biochemical changes. Clinical exome sequencing revealed a never before described heterozygote mutation in the GNAS gene (NM_000516.5 c.118_139 + 51del) of autosomal dominant maternal transmission in the three siblings, confirming the diagnosis of PHP1A. CONCLUSIONS: This study reported on a novel mutation of GNAS gene and highlighted the clinical heterogeneity of PHP1A characterized by wide genotype-phenotype variability. The appropriate diagnosis has crucial implications for patient care and long-term multidisciplinary follow-up.

Genetic underpinnings explored: OPA1 deletion and complex phenotypes on chromosome 3q29.

BACKGROUND: Copy number variations (CNVs) have emerged as significant contributors to the elusive genetic causality of inherited eye diseases. In this study, we describe a case with optic atrophy and a brain aneurysm, in which a de novo CNV 3q29 deletion was identified. CASE PRESENTATION: A 40-year-old female patient was referred to our department after undergoing aneurysm transcatheter arterial embolization for a brain aneurysm. She had no history of systemic diseases, except for unsatisfactory best-corrected visual acuity (BCVA) since elementary school. Electrophysiological tests confirmed the findings in retinal images, indicating optic nerve atrophy. Chromosomal microarray analysis revealed a de novo deletion spanning 960 kb on chromosome 3q29, encompassing OPA1 and six neighboring genes. Unlike previously reported deletions in this region associated with optic atrophy, neuropsychiatric disorders, and obesity, this patient displayed a unique combination of optic atrophy and a brain aneurysm. However, there is no causal relationship between the brain aneurysm and the CNV. CONCLUSION: In conclusion, the optic atrophy is conclusively attributed to the OPA1 deletion, and the aneurysm could be a coincidental association. The report emphasizes the likelihood of underestimating OPA1 deletions due to sequencing technology limitations. Recognizing these constraints, healthcare professionals must acknowledge these limitations and consistently search for OPA1 variants/deletions in Autosomal Dominant Optic Atrophy (ADOA) patients with negative sequencing results. This strategic approach ensures a more comprehensive exploration of copy-number variations, ultimately enhancing diagnostic precision in the field of genetic disorders.

A novel variant in NSUN2 causes intellectual disability in a Chinese family.

NSUN2-intellectual disability syndrome, also known as intellectual disability type 5 (MRT5), is an autosomal recessive disorder that is characterized by intellectual disability (ID), postnatal growth retardation, dysmorphic facies, microcephaly, short stature, developmental delay, language impairment and other congenital abnormalities. The disease is caused by mutations in the NSUN2 gene, which encodes a tRNA cytosine methyltransferase that has an important role in spindle assembly during mitosis and chromosome segregation. In this study, we recruited a family that had two individuals with ID. Whole exome sequencing was performed to identify a homozygous frameshift variant (c.1171_1175delACCAT(p.Thr391fs*18*)) in NSUN2 (NM_017755.5) in the proband. The varint was confirmed as segregating in his affected brother and his parents by Sanger sequencing. The individuals that we described showed a similar dysmorphology profile to that associated with MRT5. To analyze the correlations between genotypes of NSUN2 and phenotypes of individuals with ID, we examined 17 variants and the associated phenotypes from 32 ID individuals in current and previous studies. We concluded that mutations in NSUN2 cause a wide range of phenotypic defects. Although some clinical manifestations were highly variable, the core phenotypes associated with NSUN2 mutations were dysmorphic facies, microcephaly, short stature, ID, growth restriction, language impairment, hypotonia and delayed puberty. Our study expands the genetic spectrum of NSUN2 mutations and helps to further define the genotype-phenotype correlations in MRT5.

Case report: Novel compound heterozygous IL1RN mutations as the likely cause of a lethal form of deficiency of interleukin-1 receptor antagonist.

Undiagnosed monogenic diseases represent a challenging group of human conditions highly suspicious to have a genetic origin, but without conclusive evidences about it. We identified two brothers born prematurely from a non-consanguineous healthy couple, with a neonatal-onset, chronic disease characterized by severe skin and bone inflammatory manifestations and a fatal outcome in infancy. We conducted DNA and mRNA analyses in the patients' healthy relatives to identify the genetic cause of the patients' disease. DNA analyses were performed by both Sanger and next-generation sequencing, which identified two novel heterozygous IL1RN variants: the intronic c.318 + 2T>G variant in the father and a ≈2,600-bp intragenic deletion in the mother. IL1RN mRNA production was markedly decreased in both progenitors when compared with healthy subjects. The mRNA sequencing performed in each parent identified two novel, truncated IL1RN transcripts. Additional experiments revealed a perfect intrafamilial phenotype-genotype segregation following an autosomal recessive inheritance pattern. The evidences shown here supported for the presence of two novel loss-of-function (LoF) IL1RN pathogenic variants in the analyzed family. Biallelic LoF variants at the IL1RN gene cause the deficiency of interleukin-1 receptor antagonist (DIRA), a monogenic autoinflammatory disease with marked similarities with the patients described here. Despite the non-availability of the patients' samples representing the main limitation of this study, the collected evidences strongly suggest that the patients described here suffered from a lethal form of DIRA likely due to a compound heterozygous genotype at IL1RN, thus providing a reliable genetic diagnosis based on the integration of old medical information with currently obtained genetic data.

Biallelic variants identified in 36 Pakistani families and trios with autism spectrum disorder.

With its high rate of consanguineous marriages and diverse ethnic population, little is currently understood about the genetic architecture of autism spectrum disorder (ASD) in Pakistan. Pakistan has a highly ethnically diverse population, yet with a high proportion of endogamous marriages, and is therefore anticipated to be enriched for biallelic disease-relate variants. Here, we attempt to determine the underlying genetic abnormalities causing ASD in thirty-six small simplex or multiplex families from Pakistan. Microarray genotyping followed by homozygosity mapping, copy number variation analysis, and whole exome sequencing were used to identify candidate. Given the high levels of consanguineous marriages among these families, autosomal recessively inherited variants were prioritized, however de novo/dominant and X-linked variants were also identified. The selected variants were validated using Sanger sequencing. Here we report the identification of sixteen rare or novel coding variants in fifteen genes (ARAP1, CDKL5, CSMD2, EFCAB12, EIF3H, GML, NEDD4, PDZD4, POLR3G, SLC35A2, TMEM214, TMEM232, TRANK1, TTC19, and ZNF292) in affected members in eight of the families, including ten homozygous variants in four families (nine missense, one loss of function). Three heterozygous de novo mutations were also identified (in ARAP1, CSMD2, and NEDD4), and variants in known X-linked neurodevelopmental disorder genes CDKL5 and SLC35A2. The current study offers information on the genetic variability associated with ASD in Pakistan, and demonstrates a marked enrichment for biallelic variants over that reported in outbreeding populations. This information will be useful for improving approaches for studying ASD in populations where endogamy is commonly practiced.

A de novo dominant-negative variant is associated with OTULIN-related autoinflammatory syndrome.

OTULIN-related autoinflammatory syndrome (ORAS), a severe autoinflammatory disease, is caused by biallelic pathogenic variants of OTULIN, a linear ubiquitin-specific deubiquitinating enzyme. Loss of OTULIN attenuates linear ubiquitination by inhibiting the linear ubiquitin chain assembly complex (LUBAC). Here, we report a patient who harbors two rare heterozygous variants of OTULIN (p.P152L and p.R306Q). We demonstrated accumulation of linear ubiquitin chains upon TNF stimulation and augmented TNF-induced cell death in mesenchymal stem cells differentiated from patient-derived iPS cells, which confirms that the patient has ORAS. However, although the de novo p.R306Q variant exhibits attenuated deubiquitination activity without reducing the amount of OTULIN, the deubiquitination activity of the p.P152L variant inherited from the mother was equivalent to that of the wild-type. Patient-derived MSCs in which the p.P152L variant was replaced with wild-type also exhibited augmented TNF-induced cell death and accumulation of linear chains. The finding that ORAS can be caused by a dominant-negative p.R306Q variant of OTULIN furthers our understanding of disease pathogenesis.

Discovery of a novel homozygous SOD1 truncating variant bolsters infantile SOD1 deficiency syndrome.

OBJECTIVE: Superoxide dismutase 1 (SOD1) is an important antioxidant enzyme whose main function is to neutralise superoxide free radicals in the cytoplasm. Heterozygous variants in SOD1 are responsible for a substantial percentage of familial amyotrophic lateral sclerosis (ALS) cases. Recently, several reports have shown that biallelic loss of SOD1 function results in a novel phenotype called infantile SOD1 deficiency syndrome, which is consistent with a recessive pattern of inheritance and can be distinguished from typical (adult-onset) ALS. METHODS: We documented detailed family histories and clinical data, followed by whole-exome sequencing and family co-segregation analysis through Sanger sequencing. To facilitate comparisons, relevant data from fifteen previously reported patients with SOD1-related neurodevelopmental disorders were included. RESULTS: This study presents a new Turkish family with two affected children exhibiting severe delayed motor development, infancy-onset loss of motor skills, axial hypotonia, tetraspasticity, and impaired cognitive functions. Genetic analysis revealed a novel homozygous frameshift variant in SOD1 (c.248dupG [p.Asp84Argfs*8]), with computational biochemical studies shedding light on the mechanistic aspects of SOD1 dysfunction. CONCLUSIONS: Our findings contribute an affirmative report of a fourth biallelic variant resulting in a severe clinical phenotype, reminiscent of those induced by previously identified homozygous loss-of-function SOD1 variants. This research not only advances our understanding of the pathogenesis of this debilitating neurological syndrome but also aligns with ongoing intensive efforts to comprehend and address SOD1-linked ALS.

Newborn Screening for ß-Thalassemia Identifies a Complex Genotype Involving a Novel ß-Globin Gene Mutation (HBB:c.336dup).

Newborn screening identified a Chinese-Canadian infant who was positive for possible ß-thalassemia (ß-thal). Detailed family studies demonstrated that the proband was a compound heterozygote for the Chinese Gγ(Aγδß)0-thal deletion and a novel frameshift mutation within exon 3 (HBB:c.336dup), and heterozygous for the Southeast Asian α-thal deletion (--SEA/αα). This case illustrates the importance of follow-up molecular testing of positive newborn screening results to confirm the diagnosis and define risks for future pregnancies.

Thrombosis Tendency After Splenectomy in a Danish Family With Hemoglobin Volga, and a Literature Review.

Hemoglobin (Hb) Volga is a rare, unstable ß-chain hemoglobin variant (ß27 Ala→Asp), causing chronic hemolytic anemia. This study presents two members of a Danish family, splenectomized due to Hb Volga at and with multiple thrombotic events. The proband was diagnosed with Hb Volga 9 years old and splenectomy was performed as a part of treatment. Throughout his life, he experienced multiple superficial thrombophlebitis, two episodes of distal deep venous thrombosis (DVT) on lower extremities (age 32 and 33) and a transient ischemic attack (TIA) presented as amaurosis fugax (age 51). Thrombophilia investigation was normal. The proband's son was diagnosed with Hb Volga and underwent splenectomy at the age of 6. Despite anticoagulation therapy, he suffered from multiple venous thromboembolic events in his youth and died of chronic pulmonary embolism (PE)/pulmonary hypertension combined with infection. Given the observed propensity for multiple thromboses in these two patients, a literature review was conducted investigating reported occurrence of thrombotic events in individuals with Hb Volga.Currently 25 cases of Hb Volga are reported worldwide. The clinical symptoms primarily described are related to hemolytic anemia. Splenectomy is reported in 15 patients. Thromboses have previously been reported in only three patients who were also splenectomized. These cases involved DVT and PE, myocardial infarction, and an unspecified thrombotic event. The proband represents the first reported Hb Volga case with both venous and arterial thrombotic disorders. The exact mechanism underlying thrombotic tendency in patients with Hb Volga remains unknown, but it is probably associated with splenectomy.

Temporal dynamics of genetic parameters and SNP effects for performance and disorder traits in poultry undergoing genomic selection.

Accurate genetic parameters are crucial for predicting breeding values and selection responses in breeding programs. Genetic parameters change with selection, reducing additive genetic variance and changing genetic correlations. This study investigates the dynamic changes in genetic parameters for residual feed intake (RFI), gain (GAIN), breast percentage (BP), and femoral head necrosis (FHN) in a broiler population that undergoes selection, both with and without the use of genomic information. Changes in single nucleotide polymorphism (SNP) effects were also investigated when including genomic information. The dataset containing 200,093 phenotypes for RFI, 42,895 for BP, 203,060 for GAIN, and 63,349 for FHN was obtained from 55 mating groups. The pedigree included 1,252,619 purebred broilers, of which 154,318 were genotyped with a 60K Illumina Chicken SNP BeadChip. A Bayesian approach within the GIBBSF90 + software was applied to estimate the genetic parameters for single-, two-, and four-trait models with sliding time intervals. For all models, we used genomic-based (GEN) and pedigree-based approaches (PED), meaning with or without genotypes. For GEN (PED), heritability varied from 0.19 to 0.2 (0.31 to 0.21) for RFI, 0.18 to 0.11 (0.25 to 0.14) for GAIN, 0.45 to 0.38 (0.61 to 0.47) for BP, and 0.35 to 0.24 (0.53 to 0.28) for FHN, across the intervals. Changes in genetic correlations estimated by GEN (PED) were 0.32 to 0.33 (0.12 to 0.25) for RFI-GAIN, -0.04 to -0.27 (-0.18 to -0.27) for RFI-BP, -0.04 to -0.07 (-0.02 to -0.08) for RFI-FHN, -0.04 to 0.04 (0.06 to 0.2) for GAIN-BP, -0.17 to -0.06 (-0.02 to -0.01) for GAIN-FHN, and 0.02 to 0.07 (0.06 to 0.07) for BP-FHN. Heritabilities tended to decrease over time while genetic correlations showed both increases and decreases depending on the traits. Similar to heritabilities, correlations between SNP effects declined from 0.78 to 0.2 for RFI, 0.8 to 0.2 for GAIN, 0.73 to 0.16 for BP, and 0.71 to 0.14 for FHN over the eight intervals with genomic information, suggesting potential epistatic interactions affecting genetic trait architecture. Given rapid genetic architecture changes and differing estimates between genomic and pedigree-based approaches, using more recent data and genomic information to estimate variance components is recommended for populations undergoing genomic selection to avoid potential biases in genetic parameters.

Genetic parameters are used to predict breeding values for individuals in breeding programs undergoing selection. However, inaccurate genetic parameters can cause breeding values to be biased, and genetic parameters can change over time due to multiple factors. This study aimed to investigate how genetic parameters changed over time in a broiler population using time intervals and observing the behavior of single nucleotide polymorphism (SNP) effects. We studied four traits related to production and disorders while also studying the impact of using genomic information on the estimates. Genetic variances showed an overall decreasing trend, whereas residual variances increased during each interval, resulting in decreasing heritability estimates. Genetic correlations between traits varied but with no major changes over time. Estimates tended to be lower when genomic information was included in the analysis. SNP effects showed changes over time, indicating changes to the genetic background of this population. Using outdated variance components in a population under selection may not represent the current population. Furthermore, when genomic selection is practiced, accounting for this information while estimating variance components is important to avoid biases.

A novel SOX10 mutation causing Waardenburg syndrome type 2 by expressing a truncated and dysfunctional protein in a Chinese child.

OBJECTIVES: This study aimed to identify the causative variants in a patient with Waardenburg syndrome (WS) type 2 using whole exome sequencing (WES). METHODS: The clinical features of the patient were collected. WES was performed on the patient and his parents to screen causative genetic variants and Sanger sequencing was performed to validate the candidate mutation. The AlphaFold2 software was used to predict the changes in the 3D structure of the mutant protein. Western blotting and immunocytochemistry were used to determine the SOX10 mutant in vitro. RESULTS: A de novo variant of SOX10 gene, NM_006941.4: c.707_714del (p. H236Pfs*42), was identified, and it was predicted to disrupt the wild-type DIM/HMG conformation in SOX10. In-vitro analysis showed an increased level of expression of the mutant compared to the wild-type. CONCLUSIONS: Our findings helped to understand the genotype-phenotype association in WS2 cases with SOX10 mutations.

Detection of Novel BEST1 Variations in Autosomal Recessive Bestrophinopathy Using Third-generation Sequencing.

OBJECTIVE: Autosomal recessive bestrophinopathy (ARB), a retinal degenerative disease, is characterized by central visual loss, yellowish multifocal diffuse subretinal deposits, and a dramatic decrease in the light peak on electrooculogram. The potential pathogenic mechanism involves mutations in the BEST1 gene, which encodes Ca2+-activated Cl- channels in the retinal pigment epithelium (RPE), resulting in degeneration of RPE and photoreceptor. In this study, the complete clinical characteristics of two Chinese ARB families were summarized. METHODS: Pacific Biosciences (PacBio) single-molecule real-time (SMRT) sequencing was performed on the probands to screen for disease-causing gene mutations, and Sanger sequencing was applied to validate variants in the patients and their family members. RESULTS: Two novel mutations, c.202T>C (chr11:61722628, p.Y68H) and c.867+97G>A, in the BEST1 gene were identified in the two Chinese ARB families. The novel missense mutation BEST1 c.202T>C (p.Y68H) resulted in the substitution of tyrosine with histidine in the N-terminal region of transmembrane domain 2 of bestrophin-1. Another novel variant, BEST1 c.867+97G>A (chr11:61725867), located in intron 7, might be considered a regulatory variant that changes allele-specific binding affinity based on motifs of important transcriptional regulators. CONCLUSION: Our findings represent the first use of third-generation sequencing (TGS) to identify novel BEST1 mutations in patients with ARB, indicating that TGS can be a more accurate and efficient tool for identifying mutations in specific genes. The novel variants identified further broaden the mutation spectrum of BEST1 in the Chinese population.

[Analysis of three Chinese pedigrees affected with Hereditary factor â ¦ deficiency due to compound heterozygous variants of F7 gene].

OBJECTIVE: To analyze the types of genetic variants and clinical characteristics of three Chinese pedigrees affected with Hereditary coagulation factor Ⅶ (FⅦ) deficiency. METHODS: Three pedigrees who had visited the First Affiliated Hospital of Wenzhou Medical University between December 2021 and October 2022 were selected as the study subjects. Prothrombin time (PT), activated partial thromboplastin time (APTT) and FⅦ activity (FⅦ:C) were measured in the three probands and their pedigree members. All exons and their flanking sequences were analyzed by direct sequencing, and candidate variants were verified by reverse sequencing. The corresponding variant loci in the family members were also analyzed. ClustalX-2.1-win was used to analyze the conservation of the variant loci. Varcards and Spcards online software was used to predict the pathogenicity of the variants. Pymol software was used to analyze the changes in protein structure and molecular forces. RESULTS: Three cases of hereditary FⅦ deficiency were found to have decreased FⅦ:C, prolonged PT and normal APTT. Genetic analysis identified a total of four genetic variants, and all three probands had harbored compound heterozygous variants of the F7 gene, including p.Cys389Gly and p.His408Gln in proband 1, p.Cys389Gly and IVS6+1G>T in proband 2, and IVS6+1G>T and IVS1a+5G>A in proband 3. Conservation analysis showed that both the p.Cys389 and p.His408 loci are highly conserved among orthologous species. Analysis with Varcards and Spcards software showed that these variants were pathogenic. Protein modeling analysis showed that the p.Cys389Gly and p.His408Gln variants may result in altered protein structures and changes in hydrogen bonds. CONCLUSION: The clinical manifestations of the three FⅦ-deficient probands may be attributed to the compound heterozygous variants of p.Cys389Gly/p.His408Gln, p.Cys389Gly/IVS6+1G>T and IVS6+1G>T/IVS1a+5G>A of the F7 gene. The combination of the three compound heterozygous variants was unreported previously.

[Genetic analysis of a Chinese pedigree affected with atypical Charcot-Marie-Tooth disease type 1A due to duplication of PMP22 gene].

OBJECTIVE: To explore the clinical manifestations and genetic basis for a Chinese pedigree affected with atypical Charcot-Marie-Tooth disease type 1 A (CMT1A). METHODS: A patient admitted to the Department of Neurology, Xijing Hospital Affiliated to Air Force Medical University in June 2022 was selected as the study subject. Clinical data of the patient was collected, and 17 family members from four generations of this pedigree were traced based on pes arcuatus and atypical clinical symptoms. Neuroultrasound and genetic testing were carried out on available family members. Whole exome sequencing and multiple ligation-dependent probe amplification assay were carried out for the proband and some of the affected members of the pedigree. RESULTS: The proband, a 15-year-old male, had presented with paroxystic limb pain with weakness, accompanied by pes cavus and hypertrophy of gastrocnemius muscles, without stork leg sign caused by muscles atrophy in the distal lower extremities. MRI has revealed no sign of fat infiltration in the muscles of both legs. Nerve conduction examination had indicated damages of the sensory and motor nerves of the limbs, mainly with demyelinating changes. Seven members of the pedigree had pes arcuatus, including 5 presenting with paroxysmal neuropathic pain and myasthenia in the limbs, whilst 2 were without any clinical symptoms. Neurosonography of the proband, his brother, father and aunt showed thickened peripheral nerves of the extremities with unclear bundle structure. Genetic analysis revealed a large repeat encompassing exons 1 to 5 of the PMP22 gene and flanking regions (chr17: 15133768_15502298) in some of the affected members, which was predicted to be pathogenic. CONCLUSION: The duplication of PMP22 gene was considered to be pathogenic for this CMT1A pedigree.

[Clinical and genetic analysis of two pedigrees affected with Carnitine-acylcarnitine translocase deficiency due to variant of SLC25A20 gene].

OBJECTIVE: To analyze the clinical phenotype and genotypes of two children with Carnitine-acylcarnitine translocase deficiency (CACTD). METHODS: Two children diagnosed with CACTD at the Gansu Provincial Maternal and Child Health Care Hospital respectively on January 3 and November 19, 2018 were selected as the study subjects. Trio-whole exome sequencing (trio-WES) was carried out, and candidate variants were validated through Sanger sequencing and pathogenicity analysis. RESULTS: Both children were males and had manifested mainly with hypoglycemia. Trio-WES and Sanger sequencing showed that child 1 had harbored compound heterozygous variants of the SLC25A20 gene, namely c.49G>C (p.Gly17Arg) and c.106-2A>G, which were inherited from his father and mother, respectively. Child 2 had harbored homozygous c.199-10T>G variants of the SLC25A20 gene, which were inherited from both of his parents. Among these, the c.106-2A>G and c.49G>C variants were unreported previously. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.49G>C (p.Gly17Arg), c.106-2A>G, and c.199-10T>G variants were classified as likely pathogenic (PM2_supporting+PP3+PM3_strong+PP4), pathogenic (PVS1+PM2_supporting+PM5+PP3), and pathogenic (PVS1+PM2_supporting+PP3+PP5), respectively. CONCLUSION: Combined with their clinical phenotype and genetic analysis, both children were diagnosed with CACTD. Above finding has provided a basis for their treatment as well as genetic counseling and prenatal diagnosis for their families.

Identification of Novel FZD4 Mutations in Familial Exudative Vitreoretinopathy and Investigating the Pathogenic Mechanisms of FZD4 Mutations.

Purpose: The purpose of this study is to report five novel FZD4 mutations identified in familial exudative vitreoretinopathy (FEVR) and to analyze and summarize the pathogenic mechanisms of 34 of 96 reported missense mutations in FZD4. Methods: Five probands diagnosed with FEVR and their family members were enrolled in the study. Ocular examinations and targeted gene panel sequencing were conducted on all participants. Plasmids, each carrying 29 previously reported FZD4 missense mutations and five novel mutations, were constructed based on the selection of mutations from each domain of FZD4. These plasmids were used to investigate the effects of mutations on protein expression levels, Norrin/ß-catenin activation capacity, membrane localization, norrin binding ability, and DVL2 recruitment ability in HEK293T, HEK293STF, and HeLa cells. Results: All five novel mutations (S91F, V103E, C145S, E160K, C377F) responsible for FEVR were found to compromise Norrin/ß-catenin activation of FZD4 protein. After reviewing a total of 34 reported missense mutations, we categorized all mutations based on their functional changes: signal peptide mutations, cysteine mutations affecting disulfide bonds, extracellular domain mutations influencing norrin binding, transmembrane domain (TM) 1 and TM7 mutations impacting membrane localization, and intracellular domain mutations affecting DVL2 recruitment. Conclusions: We expanded the spectrum of FZD4 mutations relevant to FEVR and experimentally demonstrated that missense mutations in FZD4 can be classified into five categories based on different functional changes.

Expanding the Genetic Spectrum of AGXT Gene Variants in Egyptian Patients with Primary Hyperoxaluria Type I.

Introduction: Approximately 80% of primary hyperoxaluria cases are caused by primary hyperoxaluria type 1 (PH1, OMIM# 259900), which is characterized by pathogenic variants in the AGXT gene, resulting in deficiency of the liver-specific enzyme alanine-glyoxylate aminotransferase (AGT). This leads to increased production of oxalate, which cannot be effectively eliminated from the body, resulting in its accumulation primarily in the kidneys and other organs. Subjects and Methods: This study included 17 PH1 Egyptian patients from 12 unrelated families, recruited from the Inherited Kidney Disease Outpatient Clinic and the Dialysis Units, Cairo University Hospitals, during the period from January 2018 to December 2019, aiming to identify the pathogenic variants in the AGXT gene. Results: Six different variants were detected. These included three frameshift and three missense variants, all found in homozygosity within the respective families. The most common variant was c.121G>A;p.(Gly41Arg) detected in four families, followed by c.725dup;p.(Asp243GlyfsTer12) in three families, c.33dup;p.(Lys12Glnfs156) in two families, and c.731T >C;p.(Ile244Thr), c.33delC;p.(Lys12Argfs34), and c.568G>A;p.(Gly190Arg) detected in one family each. Conclusion: Consanguineous Egyptian families with history of renal stones or renal disease suspicious of primary hyperoxaluria should undergo AGXT genetic sequencing, specifically targeting exons 1 and 7, as variants in these two exons account for >75% of disease-causing variants in Egyptian patients with confirmed PH1.

Waardenburg syndrome type 2 with a de novo variant of the SOX10 gene: a case report.

BACKGROUND: Waardenburg syndrome type 2 (WS2) has been reported to be a rare hereditary disorder, which is distinguished by vivid blue eyes, varying degrees of hearing impairment, and abnormal pigment deposition in the skin and hair. Variants in the sex-determining region Y-box containing gene 10 (SOXl0) gene may cause congenital deafness and have been demonstrated to be important during the development of WS2. METHODS: Complete clinical data of the proband and her family members (her parents and 2 sisters) was collected and physical examinations were performed in the hospital. The laboratory examination including hemoglobin, Coomb's test, urine protein, ENA, autoimmune hepatitis-related autoantibodies and ultrasonography were all conducted. We obtained the peripheral blood samples from all the participants and performed whole exome sequencing and sanger sequencing validation. RESULTS: The present study identified a family of 5 members, and only the proband exhibited typical WS2. Beyond the characteristics of WS2, the proband also manifested absence of puberty. The proband and her younger sister manifested systemic lupus erythematosus (SLE). Whole exome sequencing revealed a de novo variant in the SOX10 gene. The variant c.175 C > T was located in exon 2 of the SOX10 gene, which is anticipated to result in early termination of protein translation. CONCLUSION: The present study is the first to report a case of both WS2 and SLE, and the present findings may provide a new insight into WS2.

Genotype-phenotype associations in CRB1 bi-allelic patients: a novel mutation, a systematic review and meta-analysis.

PURPOSE: The goal of the study was to search for novel bi-allelic CRB1 mutations, and then to analyze the CRB1 literature at the genotypic and phenotypic levels. APPROACH: We screened various variables such as the CRB1 mutation types, domains, exons, and genotypes and their relation with specific ocular phenotypes. An emphasis was given to the bi-allelic missense and nonsense mutations because of their high prevalence compared to other mutation types. Finally, we quantified the effect of various non-modifiable factors over the best-corrected visual acuity oculus uterque (BCVA OU) using multivariate linear regression models and identified genetic interactions. RESULTS: A novel bi-allelic missense in the exon 9 of CRB1; c.2936G > A; p.(Gly979Asp) was found to be associated with rod-cone dystrophy (RCD). CRB1 mutation type, exons, domains, and genotype distribution varied significantly according to fundus characteristics, such as peripheral pigmentation and condition, optic disc, vessels, macular condition, and pigmentation (P < 0.05). Of the 154 articles retrieved from PubMed, 96 studies with 439 bi-allelic CRB1 patients were included. Missense mutations were significantly associated with an absence of macular pigments, pale optic disc, and periphery pigmentation, resulting in a higher risk of RCD (P < 0.05). In contrast, homozygous nonsense mutations were associated with macular pigments, periphery pigments, and a high risk of LCA (P < 0.05) and increased BCVA OU levels. We found that age, mutation types, and inherited retinal diseases were critical determinants of BCVA OU as they significantly increased it by 33% 26%, and 38%, respectively (P < 0.05). Loss of function alleles additively increased the risk of LCA, with nonsense having a more profound effect than indels. Finally, our analysis showed that p.(Cys948Tyr) and p.(Lys801Ter) and p.(Lys801Ter); p.(Cys896Ter) might interact to modify BCVA OU levels. CONCLUSION: This meta-analysis updated the literature and identified genotype-phenotype associations in bi-allelic CRB1 patients.