Interferon type I signature associated with skin disease in juvenile dermatomyositis.

Background: Interferon type I (IFN-I) signaling system hyperactivation plays an important role in the pathogenesis of juvenile dermatomyositis (JDM). Aim of the study: To analyze IFN-I score with disease activity in patients with JDM. Materials and methods: Clinical manifestations laboratory data, and treatment options were analyzed in 15 children with JDM. Disease activity was assessed by CMAS (childhood myositis assessment tool) and CAT (cutaneous assessment tool) scores. IFN I-score was assessed by RT-PCR quantitation of 5 IFN I-regulated transcripts (IFI44L, IFI44, IFIT3, LY6E, MXA1). Results: All patients had skin and muscle involvement, some had a fever (n = 8), swallowing disorders (n = 4), arthritis (n = 5), calcinosis (n = 3), lipodystrophy (n = 2), and interstitial lung disease (n = 5). Twelve patients had elevated IFN I-score and it was correlated with skin disease activity. Ten patients had clinically active disease and the level of IFN I-score and its components were higher than in patients with inactive disease (8.8 vs. 4.2, p = 0.011). IFN I-score was evaluated in nine patients during follow-up. The simultaneous reduction of IFN I-score and its components, CMAS and CAT scores was observed. Conclusion: Skin involvement in refractory JDM is a challenging problem requiring the use of additional medications. Serum IFN I-score might be suggested as the promising biomarker of skin disease activity in JDM patients. Further investigations on patients with JDM and recurrent disease activity are needed, especially concerning biomarkers that determine the response to JAK inhibitors and treatment options for patients who don't respond to them.

Safety and efficacy of canakinumab treatment for undifferentiated autoinflammatory diseases: the data of a retrospective cohort two-centered study.

Introduction: The blockade of interleukine-1 (anakinra and canakinumab) is a well-known highly effective tool for monogenic autoinflammatory diseases (AIDs), such as familial Mediterranean fever, tumor necrosis factor receptor-associated periodic syndrome, hyperimmunoglobulinaemia D syndrome, and cryopyrin-associated periodic syndrome, but this treatment has not been assessed for patients with undifferentiated AIDs (uAIDs). Our study aimed to assess the safety and efficacy of canakinumab for patients with uAIDs. Methods: Information on 32 patients with uAIDs was retrospectively collected and analyzed. Next-generation sequencing and Federici criteria were used for the exclusion of the known monogenic AID. Results: The median age of the first episode was 2.5 years (IQR: 1.3; 5.5), that of the disease diagnosis was 5.7 years (IQR: 2.5;12.7), and that of diagnostic delay was 1.1 years (IQR: 0.4; 6.1). Patients had variations in the following genes: IL10, NLRP12, STAT2, C8B, LPIN2, NLRC4, PSMB8, PRF1, CARD14, IFIH1, LYST, NFAT5, PLCG2, COPA, IL23R, STXBP2, IL36RN, JAK1, DDX58, LACC1, LRBA, TNFRSF11A, PTHR1, STAT4, TNFRSF1B, TNFAIP3, TREX1, and SLC7A7. The main clinical features were fever (100%), rash (91%; maculopapular predominantly), joint involvement (72%), splenomegaly (66%), hepatomegaly (59%), lymphadenopathy (50%), myalgia (28%), heart involvement (31%), intestinal involvement (19%); eye involvement (9%), pleuritis (16%), ascites (6%), deafness, hydrocephalia (3%), and failure to thrive (25%). Initial treatment before canakinumab consisted of non-biologic therapies: non-steroidal anti-inflammatory drugs (NSAID) (91%), corticosteroids (88%), methotrexate (38%), intravenous immunoglobulin (IVIG) (34%), cyclosporine A (25%), colchicine (6%) cyclophosphamide (6%), sulfasalazine (3%), mycophenolate mofetil (3%), hydroxychloroquine (3%), and biologic drugs: tocilizumab (62%), sarilumab, etanercept, adalimumab, rituximab, and infliximab (all 3%). Canakinumab induced complete remission in 27 patients (84%) and partial remission in one patient (3%). Two patients (6%) were primary non-responders, and two patients (6%) further developed secondary inefficacy. All patients with partial efficacy or inefficacy were switched to tocilizumab (n = 4) and sarilumab (n = 1). The total duration of canakinumab treatment was 3.6 (0.1; 8.7) years. During the study, there were no reported Serious Adverse Events (SAEs). The patients experienced non-frequent mild respiratory infections at a rate that is similar as before canakinumab is administered. Additionally, one patient developed leucopenia, but it was not necessary to stop canakinumab for this patient. Conclusion: The treatment of patients with uAIDs using canakinumab was safe and effective. Further randomized clinical trials are required to confirm the efficacy and safety.

Hereditary Conditions Associated with Elevated Cancer Risk in Childhood.

Received January, 31, 2023 Revised March, 16, 2023 Accepted March, 18, 2023 Widespread use of the next-generation sequencing (NGS) technologies revealed that a significant percentage of tumors in children develop as a part of monogenic hereditary diseases. Predisposition to the development of pediatric neoplasms is characteristic of a wide range of conditions including hereditary tumor syndromes, primary immunodeficiencies, RASopathies, and phakomatoses. The mechanisms of tumor molecular pathogenesis are diverse and include disturbances in signaling cascades, defects in DNA repair, chromatin remodeling, and microRNA processing. Timely diagnosis of tumor-associated syndromes is important for the proper choice of cancer treatment, genetic counseling of families, and development of the surveillance programs. The review describes the spectrum of neoplasms characteristic of the most common syndromes and molecular pathogenesis of these diseases.

IFIH1 and DDX58 gene variants in pediatric rheumatic diseases.

BACKGROUND: The IFIH1 gene codes the MDA5 protein and the DDX58 gene codes the RIG-I receptor. Both proteins are parts of the interferon (IFN) I signaling pathway and are responsible for antiviral defense and innate immune response. IFIH1 and DDX58 polymorphisms are associated with a spectrum of autoimmune diseases. Rare gain-of-function IFIH1 mutations have been found in Singleton-Merten and Aicardi-Goutières syndrome, while DDX58 mutation can cause atypical Singleton-Merten syndrome. AIM: To characterize children with pediatric rheumatic diseases (PRD) carrying DDX58 or IFIH1 variants. METHODS: Clinical exome sequencing was performed on 92 children with different PRD. IFIH1 and DDX58 variants have been detected in 14 children. IFN-I score has been analyzed and the clinical characteristics of patients have been studied. RESULTS: A total of seven patients with systemic lupus erythematosus (SLE) (n = 2), myelodysplastic syndrome with SLE features at the onset of the disease (n = 1), mixed connective tissue disease (MCTD) (n = 1), undifferentiated systemic autoinflammatory disease (uSAID) (n = 3) have 5 different variants of the DDX58 gene. A common non-pathogenic variant p.D580E has been found in five children. A rare variant of uncertain significance (VUS) p.N354S was found in one patient with uSAID, a rare likely non-pathogenic variant p.E37K in one patient with uSAID, and a rare likely pathogenic variant p.Cys864fs in a patient with SLE. Elevated IFN-I score was detected in 6 of 7 patients with DDX58 variants. Seven patients had six different IFIH1 variants. They were presented with uSAID (n = 2), juvenile dermatomyositis (JDM) (n = 1), SLE-like disease (n = 1), Periodic fever with aphthous stomatitis, pharyngitis, and adenitis syndrome (n = 1), and systemic onset juvenile idiopathic arthritis (n = 1). Three patients have VUS p.E627X, one patient has benign variant p.I923V. Rare VUS p.R595H was detected in the JDM patient. Another rare VUS p.L679Ifs*2 and previously not reported variant p.V599Ffs*5 were detected in the patient with uSAID. One patient with uSAID has rare VUS p.T520A. All patients had elevated IFN-I scores. CONCLUSION: Rare compound-heterozygous IFIH1 variant (p.L679Ifs*2 and p.V599Ffs*5), heterozygous IFIH1 variant (p.T520A) and heterozygous DDX58 variant (p.Cys864fs) are probably disease causative for uSAID and SLE. The majority of patients with different DDX58 and IFI1 variants had hyperactivation of the IFN I signaling pathway.

Rituximab Biosimilar BCD020 Shows Superior Efficacy above Conventional Non-Biologics Treatment in Pediatric Lupus Nephritis: The Data of Retrospective Cohort Study.

BACKGROUND: Pediatric lupus nephritis (LN) is one of the most serious manifestations of systemic lupus erythematosus (SLE) in children, determining the outcomes of the disease. There are no standardized treatment protocols for pediatric LN, and the role of biologics has not yet been conclusively defined. OBJECTIVES: analyze the safety and efficacy of rituximab biosimilar BCD020 in pediatric patients with lupus nephritis. METHODS: in a retrospective cohort study, the data from the case histories of 25 patients with LN (10 boys and 15 girls) with an onset age of 13 (9-16) years, who failed conventional non-biologic treatment or developed corticosteroid dependence/toxicity, were included. The diagnosis was made using Systemic Lupus International Collaborating Clinics (SLICC) classification criteria. Rituximab biosimilar BCD020 was prescribed in a dosage of 375 mg/m2 every week (2-4 infusions) with repeated courses every 6-12 months (2-4 infusions) according to disease activity, B-cell depletion, and IgG levels. The dynamics of clinical and laboratory data, the activity of the disease by SLEDAI, and corticosteroid doses were assessed at the onset and during the rituximab trial. RESULTS: The main patient's characteristics were: Pre-rituximab non-biologic conventional treatment included: cyclophosphamide 15 (60%), MMF 8 (32%), azathioprine 3 (12%), hydroxychloroquine 12 (48%), and pulse therapy of methylprednisolone followed by oral methylprednisolone 25 (100%). The time before rituximab was 7.0 (3.0-24.0) months, and the whole observation period was 7.0 (0; 24) months. The initial pre-rituximab treatment slightly reduced SLEDAI levels and the proportion of patients with LN. A significant reduction of SLEDAI, the anti-dsDNA level, proteinuria, hematuria, C4 complement, ESR, and the median corticosteroid dose by 80% from the initial value, as well as the proportion of patients without corticosteroids, was observed after rituximab administration. Two deaths were observed due to catastrophic SLE with macrophage activation syndrome, accompanied by a severe infection (invasive aspergillosis, n = 2). Three patients developed serious adverse events: pneumonia (n = 2), transient agranulocytosis (n = 1) after the third rituximab infusion, and meningitis, caused by Listeria monocytosis, after the first rituximab infusion. Eight patients received antibacterial treatment for different respiratory infections without hospital admissions. CONCLUSIONS: Rituximab biosimilar BCD020 showed effectiveness in LN, whereas previous non-biologic treatment was insufficiently effective. Randomized controlled trials are required to evaluate the efficacy and safety of rituximab and evaluate the benefits when compared with conventional SLE treatment.

Hereditary cancer syndromes.

Hereditary cancer syndromes (HCSs) are arguably the most frequent category of Mendelian genetic diseases, as at least 2% of presumably healthy subjects carry highly-penetrant tumor-predisposing pathogenic variants (PVs). Hereditary breast-ovarian cancer and Lynch syndrome make the highest contribution to cancer morbidity; in addition, there are several dozen less frequent types of familial tumors. The development of the majority albeit not all hereditary malignancies involves two-hit mechanism, i.e. the somatic inactivation of the remaining copy of the affected gene. Earlier studies on cancer families suggested nearly fatal penetrance for the majority of HCS genes; however, population-based investigations and especially large-scale next-generation sequencing data sets demonstrate that the presence of some highly-penetrant PVs is often compatible with healthy status. Hereditary cancer research initially focused mainly on cancer detection and prevention. Recent studies identified multiple HCS-specific drug vulnerabilities, which translated into the development of highly efficient therapeutic options.

The Comparison of Pediatric Patients with Familial Mediterranean Fever Originated from Turkey and Crimea.

OBJECTIVE: We aimed to evaluate the clinical and laboratory features and MEFV allele distribution in Crimean Tatar familial Mediterranean fever patients and to compare them with Turkish familial Mediterranean fever patients and healthy controls. MATERIALS AND METHODS: All newly diagnosed familial Mediterranean fever patients with Crimean Tatar nationality (n = 18) in Children's Regional Hospital in Simferopol were enrolled in the study and were compared to 40 familial Mediterranean fever cases followed up at Hacettepe University, Ankara, Turkey. The distribution of MEFV alleles was assessed in the 127 unrelated healthy Crimean Tatar adults aged 20 years or more from different parts of the Crimea peninsula. RESULTS: Age and gender distribution, the frequency of colchicine resistance, and colchicine intolerance were similar between Turkish and Crimean Tatar children with familial Mediterranean fever. The duration of familial Mediterranean fever attack was shorter in Turkish patients than in Crimean Tatar (2.0 vs. 3.0 days, P < .001). Chest pain was more frequent in Turkish familial Mediterranean fever patients, whereas arthralgia, arthritis, and erysipeloid rash were more common in Crimean TatarT. MEFV allele distribution in Crimean Tatar was M694V-81%, M680I and V726A 9.5% both, and 68.6%, 14.3%, and 12.9% in Turkish, consequently. Homozygous carriers were 11%, compound-heterozygous was 6%, and heterozygous was 83%, compared to Turkish being 45%, 30%, and 25%, respectively. The allele distribution in healthy Crimean Tatar and Turkish was 10.2% and M694V was 7.1%, M680I was 1.6%, and V726A was 1.6%. CONCLUSION: The similar MEFV allele prevalence in both populations suggests the high prevalence of familial Mediterranean fever and the high number of undiagnosed patients in the Crimea peninsula. Younger age at onset, shorter duration of attacks, the prevalence of articular involvement, and erysipeloid rash were distinctive features of familial Mediterranean fever in Crimean Tatar.

Standard and increased canakinumab dosing to quiet macrophage activation syndrome in children with systemic juvenile idiopathic arthritis.

Objective: Macrophage activation syndrome (MAS) is a life-threatening, potentially fatal condition associated with systemic juvenile idiopathic arthritis (sJIA). Interleukin-1 (IL-1) is a key cytokine in the pathogenesis of sJIA MAS. Many cases of MAS are medically refractory to traditional doses of biologic cytokine inhibitors and may require increased dosing. When MAS occurs in the setting of sJIA treated with the IL-1 receptor antagonist (IL-1Ra), anakinra, increased anakinra dosing may be beneficial. Increased dosing of another IL-1 inhibitor, canakinumab, a monoclonal antibody to IL-1ß, has not been reported to treat refractory MAS in the setting of sJIA. Methods: Retrospective data collection extracted from the electronic medical record focused on canakinumab usage and dosing in 8 children with sJIA who developed MAS at a single academic center from 2011 to 2020. Results: Eight sJIA children (five girls) with median age 8.5 years (range, 0.9-14.2 years) were included in the present study. Five children developed MAS at disease onset and three during ongoing canakinumab therapy. MAS resolved in all eight children with canakinumab treatment. When the canakinumab dosing was insufficient or MAS developed during canakinumab therapy, the dosing was temporally up-titrated (four patients, maximum 300 mg per dose) without observed side effects. Conclusion: This report provides evidence for the efficacy and safety of short-term increased doses (2-3-times normal) of canakinumab in treating sJIA associated MAS. Further study of the efficacy and safety of increased doses of canakinumab for treatment of MAS in children with sJIA is warranted.

Simultaneous Onset of Pediatric Systemic Lupus Erythematosus in Twin Brothers: Case Report.

There are hundreds of twin adult patients with systemic lupus erythematosus (SLE), but male children with SLE are rarely affected. Two monozygotic twin brothers developed SLE at the age of 11 years during 1 month. The index brother manifested with Henoch-Shonlein purpura, accompanied by ANA positivity, and later developed critical left femoral arterial stenosis with high levels of anti-dsDNA, antiphospholipid antibodies, hypocomplementemia, and Coombs-positive hemolytic anemia. At that time his twin brother had only identical autoimmune findings and developed clinical manifestation (myositis and fasciitis) a month later. Both twins had increased IFN-score and shared a heterozygous variant in the RNASEL gene. Index patients developed scalp rash and nephritis 6 months after their parents refused the treatment which has been lasted for 1 year after disease diagnostics. Conclusion: The simultaneous onset of the pediatric SLE in the male twin is a very rare situation suspected monogenic origin of the disease. Further functional studies are required to confirm the causative role of the mutation.

The Safety and Efficacy of Tofacitinib in 24 Cases of Pediatric Rheumatic Diseases: Single Centre Experience.

JAK-inhibitors are small molecules blocking the JAK-STAT pathway that have proven effective in the treatment of different immune-mediated diseases in adults and juvenile idiopathic arthritis (JIA). AIM OF STUDY: To evaluate the safety and efficacy of tofacitinib in children with different rheumatic diseases. MATERIAL AND METHODS: We extracted information from 24 children with the following diagnosis: JIA (n = 15), undifferentiated systemic autoinflammatory diseases (SAIDs) (n = 7), and juvenile dermatomyositis (JDM) (n = 2) who have been treated with tofacitinib for a period of longer than 6 months. The treatment outcomes were classified according to the opinion of the attending physicians as having a complete response (CR), i.e., the absence of disease activity, or a partial response (PR)-a significant improvement of symptoms and disease activity, or no response (NR)-no changes in disease activity. RESULTS: CR was achieved in 10/24 patients; 7/15 among JIA patients, 1/2 among JDM patients, 4/7 among SAID patients, and PR in 5/15 of JIA, 1/2 of JDM, and 3/7 of SAID patients. Three non-responders with JIA discontinued tofacitinib. Corticosteroids were successfully tapered off in 11/14 patients and discontinued in 2/14 patients. Four patients had side effects not requiring treatment discontinuation: liver enzyme elevation (n = 2), hypercholesterolemia (n = 1), lymphadenitis (n = 1). CONCLUSION: JAK-inhibitors are effective new therapies for the treatment of multiple immune-mediated diseases. Our experience has shown the best results in patients with JIA and JIA-associated alopecia, and type I interferonopathies. More data from randomized controlled clinical trials are needed to use JAK-inhibitors safely in pediatric rheumatic diseases.

Identification of recurrent pathogenic alleles using exome sequencing data: Proof-of-concept study of Russian subjects.

Whole exome sequencing (WES) is a powerful tool for the cataloguing of population-specific genetic diseases. Within this proof-of-concept study we evaluated whether analysis of a small number of individual exomes is capable of identifying recurrent pathogenic alleles. We considered 106 exomes of subjects of Russian origin and revealed 13 genetic variants, which occurred more than twice and fulfilled the criteria for pathogenicity. All these alleles turned out to be indeed recurrent, as revealed by the analysis of 1045 healthy Russian donors. Eight of these variants (NAGA c.973G>A, ACADM c.985A>C, MPO c.2031-2A>C, SLC3A1 c.1400T>C, LRP2 c.6160G>A, BCHE c.293A>G, MPO c.752T>C, FCN3 c.349delC) are non-Russian-specific, as their high prevalence was previously demonstrated in other European populations. The remaining five disease-associated alleles appear to be characteristic for subjects of Russian origin and include CLCN1 c.2680C>T (myotonia congenita), DHCR7 c.453G>A (Smith-Lemli-Opitz syndrome), NUP93 c.1162C>T (steroid-resistant nephrotic syndrome, type 12), SLC26A2 c.1957T>A (multiple epiphyseal dysplasia) and EIF3F c.694T>G (mental retardation). These recessive disease conditions may be of particular relevance for the Russian Federation and other countries with a significant Slavic population.

Revisiting multiple erroneous genetic testing results and clinical misinterpretations in a patient with Li-Fraumeni syndrome: lessons for translational medicine.

BACKGROUND: Many cancer patients undergo sophisticated laboratory testing, which requires proper interpretation and interaction between different specialists. CASE PRESENTATION: We describe a patient with an extensive family history of cancer, who was diagnosed with bilateral breast cancer and two lung cancer lumps by the age of 40 years. She submitted a lung cancer specimen to a genetic profiling service, which reported the presence of the EGFR mutation (a combination of G719S and L833V substitutions) and the TP53 с.322_327del (p.G108_F109del) mutation in the tumor tissue. Possible therapeutic options were discussed at a medical conference, where one of the discussants raised a concern that the identified TP53 mutation may not necessarily be somatic, but reflect the germ-line status of the gene. Review of clinical records and follow-up dialog with the patient revealed, that she previously provided her blood for DNA analysis in two laboratories. The first laboratory utilized a custom NGS assay and did not detect the TP53 mutation, instead pointed to a potential pathogenic significance of the MSH6 c.2633 T > C (p.V878A) allele. The second laboratory revealed the TP53 с.322_327del (p.G108_F109del) allele but stated in the written report that it has an unknown pathogenic significance. To resolve the possible uncertainty regarding the role of the TP53 с.322_327del (p.G108_F109del) variant, we suggested that the patient invite her second cousin for genetic testing, as she was affected by neuroblastoma at the age of 3 years. This analysis revealed the presence of the same TP53 variant. CONCLUSION: We provide point-by-point discussion, reviewing multiple laboratory mistakes and clinical misinterpretations occurred with this patient. This case report exemplifies the need to involve rigorous clinical expertise in the daily practice of medical laboratory facilities.

Next generation sequencing analysis of consecutive Russian patients with clinical suspicion of inborn errors of immunity.

Primary immune deficiencies are usually attributed to genetic defects and, therefore, frequently referred to as inborn errors of immunity (IEI). We subjected the genomic DNA of 333 patients with clinical signs of IEI to next generation sequencing (NGS) analysis of 344 immunity-related genes and, in some instances, additional genetic techniques. Genetic causes of the disease were identified in 69/333 (21%) of subjects, including 11/18 (61%) of children with syndrome-associated IEIs, 45/202 (22%) of nonsyndromic patients with Jeffrey Modell Foundation (JMF) warning signs, 9/56 (16%) of subjects with periodic fever, 3/30 (10%) of cases of autoimmune cytopenia, 1/21 (5%) of patients with unusually severe infections and 0/6 (0%) of individuals with isolated elevation of IgE level. There were unusual clinical observations: twins with severe immunodeficiency carried a de novo CHARGE syndrome-associated SEMA3E c.2108C>T (p.S703L) allele; however, they lacked clinical features of CHARGE syndrome. Additionally, there were genetically proven instances of Netherton syndrome, Х-linked agammaglobulinemia, severe combined immune deficiency (SCID), IPEX and APECED syndromes, among others. Some patients carried recurrent pathogenic alleles, such as AIRE c.769C>T (p.R257*), NBN c.657del5, DCLRE1C c.103C>G (p.H35D), NLRP12 c.1054C>T (p.R352C) and c.910C>T (p.H304Y). NGS is a powerful tool for high-throughput examination of patients with malfunction of immunity.

Gene rearrangements in consecutive series of pediatric inflammatory myofibroblastic tumors.

BACKGROUND: Inflammatory myofibroblastic tumors (IMTs) are exceptionally rare neoplasms, which are often driven by rearranged tyrosine kinases. METHODS: This study considered 33 consecutive patients with IMT (median age, 6.6; age range, 0.6-15.8 years). RNA and cDNA were successfully obtained in 29 cases. The molecular analysis included sequential tests for 5'/3'-end unbalanced gene expression, variant-specific PCR, and next-generation sequencing (NGS). RESULTS: 5'/3'-end unbalanced ALK expression was revealed in 15/29 (52%) IMTs. Strikingly, all these tumors demonstrated high amount of ALK protein detected by immunohistochemistry. Variant-specific PCR was capable of identifying the type of ALK rearrangement in 11/15 IMTs with 5'/3'-end unbalanced ALK expression. The remaining four tumors were analyzed by NGS; two known and two novel (CLTC-ins6del84-ALK and EEF1G-ALK) ALK rearrangements were detected. Five IMTs demonstrated 5'/3'-end unbalanced ROS1 expression, and all these tumors carried TFG-ROS1 fusion. Nine tumors, which were negative for 5'/3'-end unbalanced ALK/ROS1 expression, were subjected to further analysis. Variant-specific PCR revealed two additional tumors with gene rearrangements (TFG-ROS1 and ETV6-NTRK3). The remaining seven IMTs were tested by NGS; single instances of TFG-ROS1 and novel SRF-PDGFRb translocations were detected. CONCLUSIONS: Twenty-four of 29 IMTs (83%) were shown to have druggable rearrangements involving tyrosine kinases, 20 of these 24 gene fusions were detectable by simple and inexpensive PCR assay, which is based on the detection 5'/3'-end unbalanced gene expression.

The spectrum of Lynch syndrome-associated germ-line mutations in Russia.

Hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome (LS), is a common cancer-predisposing syndrome. This study aimed to investigate the spectrum of germ-line mutations in Russian LS patients. LS-related mismatch repair (MMR) genes were analyzed in 16 patients, who were forwarded to genetic testing due to strong clinical features of LS and had high-level microsatellite instability (MSI-H) in the tumor (n = 14) or unknown MSI status (n = 2). In addition, 672 consecutive colorectal cancer (CRC) cases were screened for family history; 15 patients were younger than 50 years and reported 2 or more instances of LS-related cancers in 1st- or 2nd-degree relatives. Seven of these cases demonstrated MSI-H and therefore were subjected to DNA germ-line testing. Overall, 17/23 (74%) subjects carried LS-associated gene variants (MLH1: 10; MSH2: 4; MSH6: 2; PMS2: 1), with 2 alleles (MLH1 c.677G > T and MSH2 с.1906G > C) detected twice. Testing for recurrent mutations of 30 consecutive MSI-H CRCs led to the identification of 2 additional subjects with LS. The analysis of all relevant publications identified 28 unrelated LS patients presented in Russian medical literature and 3 unrelated Russian LS subjects described in international journals. Overall, 15/49 (31%) genetic defects revealed in Russian LS patients were represented by six recurrent alleles (MLH1: c.350C > T, c.677G > T, c.1852_1854del; MSH2: c.942+3A > T, c.1861C > T, с.1906G > C). We conclude that the founder effect for LS in Russia is seemingly less pronounced than the one for hereditary breast-ovarian cancer syndrome, however testing for recurrent LS mutations may be considered feasible in some circumstances.

ATM mutation spectrum in Russian children with ataxia-telangiectasia.

Ataxia-telangiectasia (AT) is a severe autosomal recessive orphan disease characterized by a number of peculiar clinical manifestations. Genetic diagnosis of AT is complicated due to a large size of the causative gene, ATM. We used next-generation sequencing (NGS) technology for the ATM analysis in 17 children with the clinical diagnosis of AT. Biallelic mutations in the ATM gene were identified in all studied subjects; these lesions included one large gene rearrangement, which was reliably detected by NGS and validated by multiplex ligation-dependent probe amplification (MLPA). There was a pronounced founder effect, as 17 of 30 (57%) pathogenic ATM alleles in the patients of Slavic origin were represented by three recurrent mutations (c.5932G > T, c.450_453delTTCT, and c.1564_1565delGA). These data have to be taken into account while considering the genetic diagnosis and screening for ataxia-telangiectasia syndrome.

Exome sequencing study of Russian breast cancer patients suggests a predisposing role for USP39.

PURPOSE: Germline variants in known breast cancer (BC) predisposing genes explain less than half of hereditary BC cases. This study aimed to identify missing genetic determinants of BC. METHODS: Whole exome sequencing (WES) of lymphocyte DNA was performed for 49 Russian patients with clinical signs of genetic BC predisposition, who lacked Slavic founder mutations in BRCA1, BRCA2, CHEK2, and NBS1 genes. RESULTS: Bioinformatic analysis of WES data was allowed to compile a list of 229 candidate mutations. 79 of these mutations were subjected to a three-stage case-control analysis. The initial two stages, which involved up to 797 high-risk BC patients, 1504 consecutive BC cases, and 1081 healthy women, indicated a potentially BC-predisposing role for 6 candidates, i.e., USP39 c.*208G > C, PZP p.Arg680Ter, LEPREL1 p.Pro636Ser, SLIT3 p.Arg154Cys, CREB3 p.Lys157Glu, and ING1 p.Pro319Leu. USP39 c.*208G > C was strongly associated with triple-negative breast tumors (p = 0.0001). In the third replication stage, we genotyped the truncating variant of PZP (rs145240281) and the potential splice variant of USP39 (rs112653307) in three independent cohorts of Russian, Byelorussian, and German ancestry, comprising a total of 3216 cases and 2525 controls. The data obtained for USP39 rs112653307 supported the association identified in the initial stages (the combined OR 1.72, p = 0.035). CONCLUSIONS: This study suggests the role of a rare splicing variant in BC susceptibility. USP39 encodes an ubiquitin-specific peptidase that regulates cancer-relevant tumor suppressors including CHEK2. Further epidemiological and functional studies involving these gene variants are warranted.

Exome-based search for recurrent disease-causing alleles in Russian population.

Exomes of 27 Russian subjects were analyzed for the presence of medically relevant alleles, such as protein-truncating variants (PTVs) in known recessive disease-associated genes and pathogenic missense mutations included in the ClinVar database. 36 variants (24 PTVs and 12 amino acid substitutions) were identified and then subjected to the analysis in 897 population controls. 9/36 mutations were novel, however only two of them (POLH c.490delG associated with xeroderma pigmentosum variant (XPV) and CATSPER1 c.859_860delCA responsible for spermatogenic failure) were shown to be recurrent. 27 out of 36 pathogenic alleles were already described in prior genetic studies; seven of them occurred only in the index cases, while 20 demonstrated evidence for persistence in Russian population. In particular, non-random occurrence was revealed for SERPINA1 c.1096G > A (alpha-1 antitrypsin deficiency), C8B c.1282C > T and c.1653G > A (complement component 8B deficiency), ATP7B c.3207C > A (Wilson disease), PROP1 c.301_302delAG (combined pituitary hormone deficiency), CYP21A2 c.844G > T (non-classical form of adrenogenital syndrome), EYS c.1155T > A (retinitis pigmentosa), HADHA c.1528G > C (LCHAD deficiency), SCO2 c.418G > A (cytochrome c oxidase deficiency), OTOA c.2359G > T (sensorineural deafness), C2 c.839_866del (complement component 2 deficiency), ACADVL c.848T > C (VLCAD deficiency), TGM5 c.337G > T (acral peeling skin syndrome) and VWF c.2561 G > A (von Willebrand disease, type 2N). These data deserve to be considered in future medical genetic activities.

Multigene sequencing reveals heterogeneity of NLRP12-related autoinflammatory disorders.

NLRP12-related autoinflammatory disease (NLRP12-AID) is an exceptionally rare autosomal dominant disorder caused by germline mutations in NLRP12 gene. Very few patients with NLRP12-AD have been identified worldwide; therefore, there is a scarcity of data on phenotypic presentation of this syndrome. Here we provide evidence that NLRP12-AID may have clinical manifestations characteristic for primary immune deficiencies (PID). 246 children with periodic fever (PF) of unknown origin were subjects to the next generation sequencing (NGS) analysis; 213 of these patients had signs of primary immunodeficiency (PID) manifested by recurrent infections, while 33 kids had isolated PF. The NGS panel was composed of 302 genes implicated in PID and/or AID. 15 patients (9 girls and 6 boys) with NLRP12-AID were identified. Median age of first AID-related fever episode was 12 months, ranging from 2 months to 13 years. Main clinical features of NLRP12-related AID were periodic fever (100%), abdominal pain and diarrhea (47%), arthralgia (20%), headache (20%) and failure to thrive (33%). Nine patients demonstrated increased susceptibility to infection and two children suffered from Crohn's disease. Administration of short courses of NSAID or corticosteroids resulted in resolution of the disease flare. In one severe case, canakinumab (anti-interleukin-1ß antibody) was successfully used. Significant number of patients with genetically assigned diagnosis of NLPR12-AID has clinical features which close resemble primary immune deficiency. This phenotypic overlap may result in underdiagnosis of NLPR12-AID among patients with PID.

Pattern of TSC1 and TSC2 germline mutations in Russian patients with tuberous sclerosis.

Tuberous sclerosis (TS) is a rare autosomal-dominant genetic disease. TS is manifested by the development of multiple hamartomas, which affect brain, kidneys, retina, skin and other organs. This study aimed to reveal specific features of molecular epidemiology of TS in Russia. Blood DNA samples from 61 patients with definite (n = 53) or probable (n = 8) clinical diagnosis of TS were tested for mutations in TSC1 and TSC2 genes using Sanger sequencing and MLPA analysis. Five TSC1/2 mutation-negative patients were further analyzed by exome sequencing. TSC1/2 mutations were detected in 53/61 patients (87%): 39 (74%) carried mutations in the TSC2 and 14 (26%) in the TSC1. Large rearrangements (exon deletions/duplications) affected exclusively TSC2, accounting for 15% of lesions of this gene. 6/8 (75%) patients with incomplete clinical manifestation of TS carried TSC1/2 gene lesion. Overall, 96% of detected germline TSC1/2 mutations occurred de novo. Patients with no mutation identified (NMI) differed from TSC1/2 mutation carriers, being lacking cortical tubers and subependymal nodules but having higher frequencies of renal angiomyolipomas, rhabdomyomas, and lymphangioleiomyomatosis. Exome sequencing failed to identify overt disease-causing mutation candidates among NMI patients. Russian patients with TS have increased frequency of TSC2 large gene rearrangements and TSC1/2 mutations occurring de novo as compared to other studies. Patients with suspected TS diagnosis but NMI status may represent a distinct disease entity.