Heterozygous State Research Articles

Гено-фенотипические особенности муковисцидоза у российских детей из Чеченской и Карачаево-Черкесской Республик

Background: Cystic fibrosis (CF) is an autosomal recessive disease that occurs with a frequency of 1:1,500 to 1:5,000 newborns, according to the World Health Organization. In the Russian Federation, the average incidence of the disease is 1:10,000 newborns. The medical and social significance of this disease is associated with the early disability of patients, the need for long-term treatment and constant follow-up, as well as the heterogeneity of phenotypic manifestations, which in turn requires early diagnosis using molecular genetic methods. The aim of the study: To study the clinical and molecular genetic characteristics of children with CF from the Chechen and Karachay-Cherkess Republics. Materials and methods: The study included 237 patients with a confirmed diagnosis of CF. Molecular genetic diagnostics was performed using the method of mass parallel sequencing using a hybridization target panel that includes the entire CFTR gene. Sequencing was performed on the MiSeq platform. All causal nucleotide variants were validated using Sanger sequencing. Results: The most common amino acid variants of the CFTR gene in patients with CF from the Chechen Republic are: p.Y515* (94 alleles/78.3%), p.E92K (18 alleles/15%). The presence of variants p.Y515* and p.E92K in the heterozygous state in the genotype is more often a favorable prognostic factor for the absence of pancreatic lesion. The main distinctive clinical feature of these patients is the onset of the disease with manifestations of pseudo-Bartter syndrome. The major amino acid variant of the CFTR gene in patients with CF from the Karachay-Cherkess Republic is: p.W1282* (28 alleles/70%). The number of patients with pseudo-Bartter syndrome was 54.5%. In 90% of cases, in patients who are homo- and heterozygous according to p.W1282*, a severe degree of pancreatic insufficiency was noted. Conclusion: Patients with cystic fibrosis from the Chechen and Karachay-Cherkess Republics are a difficult category of patients, despite neonatal screening, and cystic fibrosis therapy developed and implemented. This is partly due to the peculiarities of the phenotype and the unique distribution of alleles and genotypes of the CFTR gene. The high number of homozygous variants of the CFTR gene in patients from the Chechen and Karachay-Cherkess Republics is probably due to monoethnic marital assortativity.

The co-occurrence of genetic variants in the TYR and OCA2 genes confers susceptibility to albinism

Although rare genetic conditions are mostly caused by DNA sequence alterations that functionally disrupt individual genes, large-scale studies using genome sequencing have started to unmask additional complexity. Understanding how combinations of variants in different genes shape human phenotypes is expected to provide important insights into the clinical and genetic heterogeneity of rare disorders. Here, we use albinism, an archetypal rare condition associated with hypopigmentation, as an exemplar for the study of genetic interactions. We analyse data from the Genomics England 100,000 Genomes Project alongside a cohort of 1120 individuals with albinism, and investigate the effect of dual heterozygosity for the combination of two established albinism-related variants: TYR:c.1205 G > A (p.Arg402Gln) [rs1126809] and OCA2:c.1327 G > A (p.Val443Ile) [rs74653330]. As each of these changes alone is insufficient to cause disease when present in the heterozygous state, we sought evidence of synergistic effects. We show that, when both variants are present, the probability of receiving a diagnosis of albinism is significantly increased (odds ratio 12.8; 95% confidence interval 6.0 – 24.7; p-value 2.1 ×10−8). Further analyses in an independent cohort, the UK Biobank, support this finding and highlight that heterozygosity for the TYR:c.1205 G > A and OCA2:c.1327 G > A variant combination is associated with statistically significant alterations in visual acuity and central retinal thickness (traits that are considered albinism endophenotypes). The approach discussed in this report opens up new avenues for the investigation of oligogenic patterns in apparently Mendelian disorders.

Defects in the Maturation of Mitochondrial Iron-Sulfur Proteins: Biophysical Investigation of the MMDS3 Causing Gly104Cys Variant of IBA57.

Multiple mitochondrial dysfunctions syndrome type 3 (MMDS3) is a rare autosomal recessive mitochondrial leukoencephalopathy caused by biallelic pathogenic variants in the IBA57 gene. The gene protein product, IBA57, has an unknown role in iron-sulfur (Fe-S) cluster biogenesis but is required for the maturation of mitochondrial [4Fe-4S] proteins. To better understand the role of IBA57 in MMDS3, we have investigated the impact of the pathogenic p.Gly104Cys (c.310G > T) variant on the structural and functional properties of IBA57. The Gly104Cys variant has been associated with a severe MMDS3 phenotype in both compound heterozygous and homozygous states, and defects in the activity of mitochondrial respiratory complexes and lipoic acid-dependent enzymes have been demonstrated in the affected patients. Size exclusion chromatography, also coupled to multiple angle light scattering, NMR, circular dichroism, and fluorescence spectroscopy characterization has shown that the Gly104Cys variant does not impair the conversion of the homo-dimeric [2Fe-2S]-ISCA22 complex into the hetero-dimeric IBA57-[2Fe-2S]-ISCA2 but significantly affects the stability of IBA57, in both its isolated form and in complex with ISCA2, thus providing a rationale for the severe MMDS3 phenotype associated with this variant.

An unusual case of Anasarca-Rapunzel syndrome

Rapunzel syndrome is a rare form of gastric trichobezoar extending into the intestine, often associated with malnutrition and protein-losing enteropathy. A 12-year-old female presented with epigastric abdominal pain, facial puffiness, bilateral lower limb swelling, and anorexia. She was a known case of sickle-thalassemia double heterozygous state but had never received a blood transfusion. Family history revealed parental separation and harsh paternal behavior. The patient was undernourished but otherwise developed normally. On examination, she was lethargic, exhibited generalized anasarca, severe anemia, signs of congestive cardiac failure, and patchy hair loss on the scalp. Abdominal examination revealed moderate ascites, hepatosplenomegaly, and a firm, mobile, non-tender epigastric mass (10×8 cm), suggestive of gastric bezoar. Laboratory findings showed microcytic hypochromic anemia with macro-ovalocytes in the context of sickle-thalassemia heterozygosity. The child required multiple blood and serum albumin transfusions for severe anemia and hypoproteinemia with anasarca. Hepatic and renal causes of anasarca were excluded. Cardiovascular and respiratory systems were normal. Contrast enhanced computed tomography (CECT) abdomen confirmed the gastric bezoar. After stabilization, exploratory laparotomy and trichobezoar evacuation were performed. Psychiatric counseling and diversion therapy were provided. The child was discharged in stable condition, with follow-up showing significant improvement in nutritional status, mood, and general well-being. This case highlights the unusual presentation of Rapunzel syndrome with generalized anasarca in a pediatric patient with underlying sickle-thalassemia, emphasizing the importance of multidisciplinary management and follow-up.

A case report of Indian siblings with short stature due to novel variant in the CEP57 gene, causing Mosaic Variegated Aneuploidy Syndrome Type 2 and review of the phenotype of related patients

IntroductionMosaic Variegated Aneuploidy Syndrome 2 (MVA2) is a rare genetic disorder characterized by a variable percentage (25–50%) of constitutional mosaic aneuploidies. To our knowledge, only 15 cases worldwide with only 1 Indian family and six pathogenic variants of MVA2 have been described.Clinical featuresWe now report a 2nd Indian family with two female siblings who presented with short stature, dysmorphism, microcephaly, and a history of consanguinity.Diagnosis and interventionKaryotyping was reported to be normal (46, XX) in both siblings. Whole exome and Sanger sequencing revealed a homozygous c.1388_1391del(p.Lys463IlefsTer3) in exon 11 in the CEP57 gene (NM_014679.5), a novel variant that leads to the termination of protein translation causing MVA2. Testing of a phenotypically typical sibling showed a heterozygous status for the identified variant.ConclusionThis report highlights an important lesson for genetic testing. Our findings enrich the CEP57 mutational spectrum and emphasize the importance of genetic testing and karyotyping in patients with microcephaly and short stature.

Sequence variants underlying severe combined immunodeficiency and leukocyte adhesion deficiency type 1 in six consanguineous families.

Inborn errors of immunity (IEI) are defined as genetic disorders affecting the immune system and resulting in diverse clinical signs and symptoms. Despite the lack of diagnosis and unavailability of IEI estimation in the Pakistani population, consanguinity is exacerbating its prevalence. The current study focuses on severe combined immunodeficiency (SCID) and leukocyte adhesion deficiency type 1 (LAD1). SCID is associated with the life-threatening symptoms developing at post-birth. LAD1 is clinically characterized by recurrent bacterial infections related to the skin, mouth, and respiratory tract owing to impaired leukocytes. Herein, in six consanguineous families, flow cytometry was used to evaluate the patient's immune status. Whole-exome sequencing (WES) was then conducted to search for the causative variations in immunodeficiency genes. Sanger sequencing was used to assess the segregation of the variants with the disorder within the families. Sequence analysis revealed five homozygous variants in four different causative genes. This included four novel nonsense variants in CD70 p.(Thr126Profs*33), CD3e p.(Trp151*), IL7R p.(Val138Ilefs*10), and ITGB2 p.(Ser627Valfs*61), and one previously reported in ITGB2 p.(Cys62*). In one of the families, two variants in two different genes, including DNAH6 p.(Tyr2653His) and NIPAL4 p.(Gly121Ser), were detected in an unclassified patient. All the identified variants were found in a homozygous state in the patient but in a heterozygous state in the available parents. The study will facilitate the diagnosis and management of IEI patients.

TARGETED SEQUENCING REVEAL TWO PATHOGENIC MUTATIONS IN LDLR AND APOE GENES IN PATIENT WITH FAMILY HYPERCHOLESTEROLEMIA: CASE REPORT

Familial hypercholesterolemia (FH) is a serious inherited disorder that can lead to early development of cardiovascular disease (CVD) due to the high blood cholesterol levels. In our study, we identified in FH patient likely pathogenic variant of LDLR and APOE genes. Interest in the homozygous state of FH is understandable given its rarity and severe health consequences. The homozygous state, when both LDL receptor alleles mutated, demonstrates even higher cholesterol levels and an earlier and more severe clinical course compared with the heterozygous state. In our study, we report an interesting case of homozygous FH due to its rare prevalence. Patient U., 16 years old, woman, admitted to the National Research Cardiac Surgery Center (NRCC), was diagnosed with FH, congenital heart disease (CHD), bicuspidal aortic valve (AV) type 1. Both parents (mother and father) were included for reliable analysis. DNA was isolated from the venous blood sample by using the column method of QIAamp DNA Mini Kit. Targeted NGS using TruSight Cardio panel for 174 genes was performed on MiSeq, Illumina. Identified genetic variants were classified according to the ACMG guidelines. Pathogenic variants were validated by Sanger sequencing. Additionally, databases of the VarSome and ClinVar were used for analysis. Sequencing of 96 genes and bioinformatics analysis identified 2 likely pathogenic variants - C526T:p.R176C in APOE and G295A:p.E99K in LDLR gene, 4 uncertain significance variants in APOB, TTN, COL3A1, NOTCH1 and 90 benign variants in APOB, TTN, LAMA4, MYPN, DMD. LDLR (G295A:p.E99K) and APOE (C526T:p.R176C) were validated and confirmed by Sanger sequencing in patients and her father and mother. The main function of the APOE gene is to make the protein apolipoprotein E, which is involved in fat metabolism. In our study, the patient had a heterozygous variant of СT polymorphism rs7412 in the APOE gene, which indicates the presence of a possible disorder of fat metabolism. LDLR gene encodes a protein called low-density lipoprotein receptor, which is responsible for the uptake of cholesterol-carrying lipoprotein particles in cells. In our study, a patient with a homozygous AA variant of the LDLR gene was found to be pathogenic. Disruption of the uptake of cholesterol-carrying lipoprotein particles in cells can have serious consequences for the body. This can lead to cholesterol accumulation in the blood and tissues, which in turn can contribute to the development of atherosclerosis and other CVD. We found that both parents had a heterozygous genotype of G295A:p.E99K in LDLR gene; and mother had a heterozygous genotype and father had a homozygous genotype of C526T:p.R176C in APOE gene. In our study, we found the genetic mutations - two likely pathogenic genetic variants LDLR (G295A:p.E99K) and APOE (C526T:p.R176C) associated with FH in patient with clinical phenotype of FH using TruSight Cardio targeted panel of 96 genes. Genetic testing using targeted NGS or whole exome sequencing would be useful for right diagnosis and might improve personalize treatment for these patients. To identify other genes associated with FH whole exome sequencing can be recommend. Supported by Committee of Science of the Ministry of Science and Higher Education of Republic of Kazakhstan (AP14869903), (BR21881970) and Nazarbayev University CRP (211123CRP1608).

A new nonsense pathogenic variant in exon 1 of PHOX2B leads to the diagnosis of congenital central hypoventilation syndrome with intra-familial variability

Congenital central hypoventilation syndrome (CCHS) is a rare genetic disorder of the autonomic nervous system resulting in decreased brain sensitivity to hypercapnia and hypoxia characterized by a genetic abnormality in the pair-like homeobox 2B (PHOX2B) gene. Most patients have a heterozygous expansion of the polyalanine repeat in exon 3 (PARM), while 10 % of patients have non-PARM (NPARM) mutations that can span the entire gene. The majority of pathogenic variants are de novo, but variants with incomplete penetrance can be identified in the heterozygous state. In the present report, CCHS was diagnosed in a symptomatic 3-month-old infant with neonatal respiratory distress. Genetic analysis revealed a new mutation in exon 1 of the PHOX2B gene – p.Ser28* (c.83C>G) – which was further identified in two family members, one minimally symptomatic and one asymptomatic. The identification of this new mutation supports the importance of sequencing the entire gene even when the classic PARM mutation is not found and highlights the phenotypic variability of CCHS.

GNE Myopathy: Genotype - Phenotype Correlation and Disease Progression in an Indian Cohort.

GNE myopathy is a rare slowly progressive adult-onset distal myopathy with autosomal recessive inheritance. It has distinctive features of quadriceps sparing with preferential anterior tibial involvement. Most patients eventually become wheelchair bound by 10-20 years after onset. This study analyzes the phenotype-genotype characteristics and disease progression in a large cohort of GNEM patients from India. Retrospective observational study on GNEM from a quaternary neurology referral hospital in southern India. Data was collected from clinical phenotyping, serum creatine kinase levels, muscle biopsy histopathology, genetic analysis and functional assessment scales - IBMFRS and MDFRS. 157 patients were included with mean age at onset and diagnosis: 26.5±6.2 years and 32.8±7.8 years, respectively. M:F ratio was 25 : 13. Most common presenting symptom: foot drop (46.5%) and limb girdle weakness (19.1%). Wasting and weakness of small muscles of hand and finger flexors seen in 66.2% and as an initial symptoms in 5.2%. Though tibialis anterior involvement was most common (89.2%), early quadriceps weakness was noted in 3.2% and Beevor's sign in 59.2%. Rimmed vacuoles were present in 75% of patients with muscle biopsy. Most common variant was the Indian Founder variant identified in 129 patients (c.2179 G>A, p.Val727Met - 82.2%) and most common zygosity being compound heterozygous state (n = 115, 87.5%). Biallelic kinase domain variations predisposed to a more severe phenotype. Wheelchair bound state noted in 8.9% with a mean age and duration of 32.0±7.1 and 6.3±4.9 years respectively, earlier than previous studies on other ethnic groups. This is the largest GNEM cohort reported from South Asia. The p.Val727Met variant in compound heterozygous state is noted in majority (82.2%) of the cases. Observed relationships between genotype and clinical parameters shows that severity of the disease might be attributable to specific GNE genotype and thus could aid in predicting the disease progression.

Optogenetic control of early embryos labeling using photoactivatable Cre recombinase 3.0.

Establishing a highly efficient photoactivatable Cre recombinase PA-Cre3.0 can allow spatiotemporal control of Cre recombinase activity. This technique may help to elucidate cell lineages, as well as facilitate gene and cell function analysis during development. This study examined the blue light-mediated optical regulation of Cre-loxP recombination using PA-Cre3.0 transgenic early mouse pre-implantation embryos. We found that inducing PA-Cre3.0 expression in the heterozygous state did not show detectable recombination activation with blue light. Conversely, in homozygous embryos, DNA recombination by PA-Cre3.0 was successfully induced by blue light and resulted in the activation of the red fluorescent protein reporter gene, while almost no leaks of Cre recombination activity were detected in embryos without light illumination. Thus, we characterize the conditions under which the PA-Cre3.0 system functions efficiently in early mouse embryos. These results are expected to provide a new optogenetic tool for certain biological studies, such as developmental process analysis and lineage tracing in early mouse embryos.

Genetic Markers of Spina Bifida in an Indian Cohort.

To identify the genetic markers of spina bifida through a systematic survey of the exome in an Indian cohort. Three consecutive patients (P1: 1 year, male; P2: 2.8 years, male; and P3: 10 years, female) with spina bifida (lumbosacral meningomyelocele) underwent whole-exome sequencing (libraries: SureSelect Human All Exon V8; sequencing: 2 * 150 bp paired-end run, 100×) with NovaSeq 6000. Data analysis was performed using SMART-One™ (secondary analysis) and SMARTer™ (tertiary analysis) for automated quality check, alignment (GRCh38/hg38), variant calling, annotation (ClinVar, OMIM, avsnp150, 1000 Genomes v5b, ExAC v0.3, gnomAD v4.0, and esp6500vi2all v0.0.25), v0.0.25), interpretation. The pathogenic and likely pathogenic (ClinVar/ InterVar), non-synonymous, exonic markers (read depth ≥ 5) were matched with the Familial Neural Tube Defects (Version 1.10) panel (FNTD panel). Pathogenic variants overlapping with the FNTD panel were MTRR, CC2D2A, and ZIC2 in P1 and P2, TGIF1 in P1 only, and none in P3. Novel pathogenic/likely pathogenic variants common to all three patients were PRUNE1, PKD1, PDZD2, and DAB2 in the homozygous state as well as in the heterozygous state, PLK1 and NLGN2. The possible role of such markers in etiopathogenesis was explored through a literatur search. The genetic landscape of the spina bifida in an Indian cohort is diverse compared to that reported from other parts of the world. A comprehensive catalog of single-nucleotide variants in the etiopathogenesis of the spina bifida on a background of the Familial Neural Tube Defects Panel has been generated.

Germline variants in acquired aplastic anemia: current knowledge and future perspectives.

Aplastic anemia (AA) is a disease characterized by failure of hematopoiesis, bone marrow aplasia, and pancytopenia. It can be inherited or acquired. Although acquired AA is believed to be immune-mediated and random, new evidence suggests an underlying genetic predisposition. Besides confirmed genomic mutations that contribute to inherited AA (such as pathogenic mutations of TERT and TERC), germline variants, often in heterozygous states, also play a not negligible role in the onset and progression of acquired AA. These variants, associated with inherited bone marrow failure syndromes and inborn errors of immunity, contribute to the disease, possibly through mechanisms including gene homeostasis, DNA repair, and immune injury. This article explores the nuanced association between acquired AA and germline variants, detailing the clinical significance of germline variants in diagnosing and managing this condition. More work is encouraged to better understand the role of immunogenic pathogenic variants and whether somatic mutations participate as secondary "hits" in the development of bone marrow failure.

Mutations of CYP1B1 and FOXC1 genes for childhood glaucoma in Japanese individuals.

To explore the frequency and positions of genetic mutations in CYP1B1 and FOXC1 in a Japanese population. Molecular genetic analysis. Genomic DNA was extracted from 31 Japanese patients with childhood glaucoma (CG) from 29 families. We examined the CYP1B, FOXC1, and MYOC genes using Sanger sequencing and whole-exome sequencing (WES). For CYP1B1, we identified 9 families that harbored novel mutations, p.A202T, p.D274E, p.Q340*, and p.V420G; the remaining mutations had been previously reported. When mapped to the CYP1B1 protein structure, all mutations appeared to influence the enzymatic activity of CYP1B1 by provoking structural deformity. Five patients were homozygotes or compound heterozygotes, supporting the recessive inheritance of the CYP1B1 mutations in CG. In contrast, four patients were heterozygous for the CYP1B1 mutation, suggesting the presence of regulatory region mutations or strong modifiers. For the FOXC1 gene, we identified 3 novel mutations, p.Q23fs, p.Q70R, and p.E163*, all of which were identified in a heterozygous state. No mutation was found in the MYOC gene in these CG patients. All individuals with CYP1B1 and FOXC1 mutations were severely affected by early-onset CG. In the CYP1B1-, FOXC1-, and MYOC-negative families, we also searched for variants in the other candidate genes reported for CG through WES, but could not find any mutations in these genes. Our analyses of 29 CG families revealed 9 families with point mutations in the CYP1B1 gene, and four of those patients appeared to be heterozygotes, suggesting the presence of complex pathogenic mechanisms. FOXC1 appears to be another major causal gene of CG, indicating that panel sequencing of CYP1B1 and FOXC1 will be useful for diagnosis of CG in Japanese individuals.

Agouti-Signaling Protein and Melanocortin-1-Receptor Mutations Associated with Coat Color Phenotypes in Fallow Deer (Dama dama).

Four dominant coat color phenotypes are found in fallow deer (Dama dama). Brown is the most common. Black, menil, and white occur with varying frequencies. In order to gain insights into the molecular genetic background of these phenotypes, 998 fallow animals (772 brown, 62 black, 126 menil, and 38 white) were examined for mutations in the ASIP, MC1R, TYR, and SLC45A2 genes. In ASIP, two mutations (ASIP-M-E2, located at the boundary from exon 2 to intron 2; and ASIP-M-E3, an InDel of five nucleotides) were found, leading to black fallow deer being either homozygous or heterozygous in combination. There were also two mutations found in MC1R. Whereby the mutation MC1R-M1 (leucine to proline, L48P) homozygous leads to a white coat, while the mutation MC1R-M2 (glycine to aspartic acid, G236D) homozygous is associated with the menil phenotype. When both mutations occur together in a heterozygous character state, it results in a menil coat. Since the mutations in the two genes are only present alternatively, 36 genotypes can be identified that form color clusters to which all animals can be assigned. No mutations were found in the TYR and SLC45A2 genes. Our investigations demonstrate that the four dominant coat colors in fallow deer can be explained by ASIP and MC1R mutations only.

Rare heterozygous variants in paediatric steroid resistant nephrotic syndrome – a population-based analysis of their significance

Genetic testing in nephrotic syndrome may identify heterozygous predicted-pathogenic variants (HPPVs) in autosomal recessive (AR) genes that are known to cause disease in the homozygous or compound heterozygous state. In such cases, it can be difficult to define the variant’s true significance and questions remain about whether a second pathogenic variant has been missed during analysis or whether the variant is an incidental finding. There are now known to be over 70 genes associated with nephrotic syndrome, the majority inherited as an AR trait. Knowledge of whether such HPPVs occur with equal frequency in patients compared to the general population would assist interpretation of their significance. Exome sequencing was performed on 187 Steroid-Resistant Nephrotic Syndrome (SRNS) paediatric patients recruited to a UK rare disease registry plus originating from clinics at Evelina, London. 59 AR podocytopathy linked genes were analysed in each patient and a list of HPPVs created. We compared the frequency of detected HPPVs with a ‘control’ population from the gnomAD database containing exome data from approximately 50,000 individuals. A bespoke filtering process was used for both patients and controls to predict ‘likely pathogenicity’ of variants. In total 130 Caucasian SRNS patients were screened across 59 AR genes and 201 rare heterozygous variants were identified. 17/201 (8.5%) were assigned as ‘likely pathogenic’ (HPPV) using our bespoke filtering method. Comparing each gene in turn, for SRNS patients with a confirmed genetic diagnosis, in 57 of the 59 genes we found no statistically significant difference in the frequency of these HPPVs between patients and controls (In genes ARHGDIA and TP53RK, we identified a significantly higher number of HPPVs in the control population compared with the patients when filtering was performed with ‘high stringency’ settings only). In the SRNS patients without a genetics diagnosis confirmed, there was no statistically significant difference identified in any gene between patient and control. In children with SRNS, we propose that identification of HPPV in AR podocytopathy linked genes is not necessarily representative of pathogenicity, given that the frequency is similar to that seen in controls for the majority. Whilst this may not exclude the presence of genetic kidney disease, this type of heterozygous variant is unlikely to be causal and each result must be interpreted in its clinical context.

The Impact of Different MEFV Genotypes on Clinical Phenotype of Patients with Familial Mediterranean Fever: Special Emphasis on Joint Involvement

Familial Mediterranean Fever (FMF) is the most common monogenic autoinflammatory disease worldwide. In this retrospective cohort study, we aimed to assess the effects of various MEFV genotypes on the clinical characteristics of the patients, with a special focus on the joint involvement. In total, 782 patients with FMF were categorized into 3 groups according to the MEFV mutation; Group 1: Patients homozygous for M694V; Group 2: Patients carrying other pathogenic MEFV variants in exon 10 in homozygous or compound heterozygous states; and Group 3: FMF patients with other variants or without mutations. Clinical and demographic findings were compared between groups. Among the 782 FMF patients, total frequency of arthritis was 237 (30.3%): 207 (26.4%) were acute monoarthritis and 67 (8.5%) were chronic arthritis. Both the frequency of arthritis (acute and/or chronic) (40.4% vs. 24.8% vs. 26.7%; p:0.001) and acute monoarthritis (35.4% vs. 20% vs. 23.7%; p:0.001) were significantly higher in Group 1 than in the other groups. FMF patients with chronic arthritis showed a distinct juvenile idiopathic arthritis (JIA) distribution pattern with a more frequent enthesitis-related arthritis (ERA) subtype (43.2%). HLA-B27 was positive in 24% of the ERA patients.Conclusion: Homozygous M694V mutation is associated with a more frequent and longer acute monoarthritis comparing to other MEFV genotypes. In addition, the risk of chronic arthritis seems not related to the MEFV mutations. However, FMF patients with chronic arthritis show a distinct ILAR JIA distribution pattern with a more frequent ERA and undifferentiated arthritis subtype.What is known:• Homozygous M694V mutation is associated with a more frequent and longer acute monoarthritisWhat is new:• FMF patients with chronic arthritis show a distinct ILAR JIA distribution pattern with a more frequent ERA subtype• ERA patients with negative HLA-B27 antigen should also be assessed for polyserositis episodes of FMF, especially in countries with high FMF carrier frequency

Characterization of Genetic Variability of Common and Tartary Buckwheat Genotypes Using Microsatellite Markers.

Buckwheat is a highly nutritional pseudocereal with antioxidant potential. The aim of this study was to analyze the genetic variability of 21 varieties of common buckwheat (Fagopyrum esculentum Moench.) and 14 varieties of Tartary buckwheat (Fagopyrum tataricum Gaertn.) using microsatellite markers. By analyzing 21 SSR markers, an average of 11.6 alleles per locus were amplified and an average PIC value of 0.711 was determined. We determined the heterozygous status of the individuals and variability in the set using the SSR analysis on the basis of expected heterozygosity (He, 0.477), observed heterozygosity (Ho, 0.675), Shannon's index (I, 0.820), and fixation indices (FST, FIS, FIT). Based on the SSR analyses, the lower level of expected heterozygosity in the analyzed set of Tartary buckwheat genotypes was observed compared to common buckwheat. With the help of a hierarchical cluster analysis using the UPGMA algorithm, Structure analysis, and PCoA analysis for the SSR markers, we divided the buckwheat varieties in the dendrogram into two main clusters according to the species. The AMOVA analysis showed that genetic variability between the individuals prevails in the analyzed set. The SSR technique proved to be a suitable tool for the determination of intra- and inter-varietal genetic variability and for analysis of diversity.

Whole paternal uniparental disomy of chromosome 4 with a novel homozygous IDUA splicing variant, c.159-9T>A, in a Chinese patient with mucopolysaccharidosis type I.

Mucopolysaccharidosis type I (MPS-I) is a rare autosomal recessive genetic lysosomal storage disorder that is caused by pathogenic variants of the α-L-iduronidase (IDUA) gene. This study aimed to identify the genetic causes of MPS-I in a Chinese patient and construct a minigene of IDUA to analyze its variants upon splicing. Whole-exome sequencing (WES) and Sanger sequencing were used to confirm the potential causative variants. Single-nucleotide polymorphism (SNP) array was subsequently performed to confirm uniparental disomy (UPD). Minigene assay was performed to analyze the effect on splicing of mRNA. We meanwhile explored the conservative analysis and protein homology simulation. A novel homozygous splicing mutation of IDUA, c.159-9T>A, was identified in an individual presenting with overlapping features of MPS-I. Interestingly, only the father and sisters, but not the mother, carried the variant in a heterozygous state. WES and SNP array analyses validated paternal UPD on chromosome 4. Minigene splicing revealed two aberrant splicing events: exon 2 skipping and intron 1 retention. Moreover, the specific structure of the mutant protein obviously changed according to the results of the homologous model. This study describes a rare autosomal recessive disorder with paternal UPD of chromosome 4 leading to the homozygosity of the IDUA splicing variant in patients with MPS-I for the first time. This study expands the variant spectrum of IDUA and provides insights into the splicing system, facilitating its enhanced diagnosis and treatment.

Tofersen decreases neurofilament levels supporting the pathogenesis of the SOD1 p.D91A variant in amyotrophic lateral sclerosis patients

BackgroundSince the antisense oligonucleotide tofersen has recently become available for the treatment of amyotrophic lateral sclerosis (ALS) caused by mutations in SOD1, determining the causality of the over 230 SOD1 variants has become even more important. The most common SOD1 variant worldwide is p.D91A (c.272A > C), whose causality for ALS is contested when in a heterozygous state. The reason is the high allele frequency of SOD1D91A in Europe, exceeding 1% in Finno-Scandinavia.MethodsWe present the clinical disease course and serum neurofilament light chain (NfL) results of treating 11 patients either homo- or heterozygous for the SOD1D91A allele for up to 16 months with tofersen.ResultsTofersen decreases serum neurofilament levels (sNFL), which are associated with the ALS progression rate, in the 6 ALS patients homozygous for SOD1D91A. We observe significantly lower sNfL levels in the 5 patients heterozygous for SOD1D91A. The results indicate that both mono- and bi-allelic SOD1D91A are causally relevant targets, with a possibly reduced effect size of SOD1D91Ahet.ConclusionsThe finding is relevant for decision making regarding tofersen treatment, patient counseling and inclusion of SOD1D91A patients in drug trials. As far as we are aware, the approach is conceptually new since it provides evidence for the causality of an ALS variant based on a biomarker response to gene-specific treatment.

Whole genome joint analysis reveals ATM:C.1564_1565del variant segregating with Ataxia-Telangiectasia and breast cancer

ATM gene is implicated in the development of breast cancer in the heterozygous state, and Ataxia-telangiectasia (A-T) in a homozygous or compound heterozygous state. Ataxia-telangiectasia (A-T) is a rare cerebellar ataxia syndrome presenting with progressive neurologic impairment, telangiectasia, and an increased risk of leukemia and lymphoma.Although the role of ATM, separately, in association with A-T and breast cancer is well documented, there is a limited number of studies investigating ATM variants when segregating with both phenotypes in the same family. Here, using joint analysis and whole genome sequencing, we investigated ATM c.1564_1565del in a family with one homozygous member presenting with A-T (OMIM # 208900) and three heterozygous members, of whom one had breast cancer (OMIM #114480). To our knowledge, this is the first study of ATM c.1564_1565del segregation with both A-T and breast cancer phenotypes within the same kindred. This study highlights the need for a comprehensive genomic approach in the appropriate cancer risk management of heterozygote carriers of ATM in families with A-T.