Monogenic Autosomal Recessive Disorder Research Articles

8488 Sex-Specific Differences in an Alstrom Syndrome Mouse Model

Abstract Disclosure: Y. Carcamo-Bahena: None. J. Youn: None. E. Lartigue: None. S. Sisley: None. Background: Alström syndrome is a monogenic autosomal recessive disorder caused by loss of the ALMS1 gene that affects 1 in 1 million. Loss of a functional ALMS1 protein leads to global disorganization of microtubules. Patients are affected by progressive vision and hearing loss and are at risk of developing obesity and type 2 diabetes. Aside from reproductive system anomalies, no clinical reports have identified sex-specific difference in patients with Alström syndrome. Methods: Male and female Alms1tvrm[1]02/tvrm[1]02 (null), Alms1tvrm[1]02/+ (heterozygous) and wildtype littermate mice were weaned onto standard chow diet. At 16 weeks of age, they were changed to a 45% high fat diet (HFD). Weekly body weights were collected and intraperitoneal glucose tolerance tests (GTTs, 1.5 g/kg D20W) were performed at three different time points (11, 16, 25 weeks of age). Results:Alms1 null mice were heavier than wildtype and heterozygous mice on standard chow diet. In males, significant changes in weight gain in null mice occurred by 10 weeks compared to wildtype and heterozygous mice (p<0.05). In females, compared to null, this change was observed by 13 weeks (p<0.05). Although female mice are typically protected from diet-induced obesity, the null females weighed the same as the null males (65.0 ± 2.0 vs 67.7 ± 2.8 g) after 9 weeks on HFD. We observed sex and diet specific differences in GTT outcomes. On chow diet, Alms1 deficiency did not affect glucose levels during a GTT in female mice. However, after 9 weeks of HFD (25 weeks of age), baseline fasting glucose levels were higher in the null females compared to wildtype (p<0.05) and heterozygotes (p<0.01). Additionally, the GTT curve was monophasic, indicating onset of diabetes whereas wildtype and heterozygotes (p<0.0001) had normal curves. Null male mice showed an impaired glucose response at 11 weeks of age on chow diet compared to wildtype and heterozygous males (p<0.001) and by 16 weeks, the GTT glucose curve for Alms1 null mice was monophasic. After 9 weeks of HFD, no differences were observed in glucose levels during a GTT. Conclusions: We observed sex-specific differences in this Alms1 null mouse model related to body weight and glucose tolerance with male null mice exhibiting earlier obesity and impaired glucose tolerance and female mice showing more pronounced effects on a HFD. Future research should investigate if these sex-specific effects alter responses to dietary or pharmaceutical interventions. Presentation: 6/1/2024

8131 A Rare Case of Autoimmune Polyendocrine Syndrome; a Menopause Despite Replacement Therapy

Abstract Disclosure: M.E. Chacon Cruz: None. M. Sanchez Cordero: None. R.M. Roman Torres: None. G. Guerra Velazquez: None. Polyendocrinopathy is a heterogeneous group of disorders leading to dysfunction of multiple endocrine glands and other tissues. The syndromes can occur in patients from early infancy to old age and new components of a given syndrome can appear throughout life. APS can be classified into APS type 1 and APS2-4. APS-1 is a rare monogenic autosomal recessive autoimmune disorder consisting of the triad of chronic mucocutaneous candidiasis, hypoparathyroidism and adrenal insufficiency. APS2 require presence of Addison disease, autoimmune thyroid disorder and type 1 diabetes. APS 3 requires presence of Thyroid autoimmune disease associated with other autoimmune diseases. APS4 is a combination of organ specific autoimmune disease non included in a previous group. Autoimmune oophoritis is found in approximately 4 percent of females who presented with spontaneous primary ovarian insufficiency and may occur in type I and II syndromes of polyglandular autoimmune failure. This is the case of 44 year old female patient with history of hypertension, hypoparathyroidism diagnose at the age of 9 year old, vitiligo and premature ovarian failure diagnose at the age of 16 year old. Patient reported that started with multiple episodes of watery non bloody diarrhea and arthralgia. Patient went to her Pediatrician and they found hypocalcemia hyperphospathemia. Patient mineral was replaced with medication and then followed by pediatric endocrinologist. Patient continues with normal life, but menstrual periods had not started even at age 16th. Laboratory work up was done and premature ovarian failure was diagnosed after that, patient started with progesterone and estrogen to induce menstrual periods. Menstrual periods began regularly and monthly. Patient continues taking medication regularly, phoslo, calcitriol, progestin and estradiol without problem until this year that despite regular medication, started with signs and symptoms of menopause with irregular menstrual periods, palpitations hot flashes, sweating, anxiety and sleep problems. Patient met criteria for APS4 due to combination of organ specific autoimmune disease such premature ovarian failure, vitiligo and hypoparathryroidism. This case is extremely important since despite the fact that there is no family history of either endocrinological or autoimmune diseases, our patient debuts throughout her life with several autoimmune diseases, such as premature ovarian failure and vitiligo. Patient had Schedule appointment with gynecologist who increased the dose of progestin and estradiol. This case highlights the importance of being vigilant about new components of a syndrome developing at different times though a patient's life. As described, autoimmune diseases commonly are related to other diseases, but without a good clinical history and physical examination could be misdiagnosed affecting the quality of life of those patients. Presentation: 6/2/2024

Comparison of Third-Generation Sequencing and Routine Polymerase Chain Reaction in Genetic Analysis of Thalassemia.

Thalassemia is the most widely distributed monogenic autosomal recessive disorder in the world. Accurate genetic analysis of thalassemia is crucial for thalassemia prevention. To compare the clinical utility of a third-generation sequencing-based approach termed comprehensive analysis of thalassemia alleles with routine polymerase chain reaction (PCR) in genetic analysis of thalassemia and explore the molecular spectrum of thalassemia in Hunan Province. Subjects in Hunan Province were recruited, and hematologic testing was performed. Five hundred four subjects positive on hemoglobin testing were then used as the cohort, and third-generation sequencing and routine PCR were used for genetic analysis. Of the 504 subjects, 462 (91.67%) had the same results, whereas 42 (8.33%) exhibited discordant results between the 2 methods. Sanger sequencing and PCR testing confirmed the results of third-generation sequencing. In total, third-generation sequencing correctly detected 247 subjects with variants, whereas PCR identified 205, which showed an increase in detection of 20.49%. Moreover, α triplications were identified in 1.98% (10 of 504) hemoglobin testing-positive subjects in Hunan Province. Seven hemoglobin variants with potential pathogenicity were detected in 9 hemoglobin testing-positive subjects. Third-generation sequencing is a more comprehensive, reliable, and efficient approach for genetic analysis of thalassemia than PCR, and allowed for a characterization of the thalassemia spectrum in Hunan Province.

Thrombocytopenia and Kidney disease, two possible hallmark of FCS phenotype: preliminary evidence from a cohort study

Background and Aim: Familial Chylomicronemia Syndrome (FCS) is a rare monogenic autosomal recessive disorder of lipid metabolism determining severe hypertriglyceridemia (HTG). As the use of Volanesorsen, a novel FCS treating drug, has been associated with thrombocytopenia, the relationship between FCS and low platelets counts should be firmly established. It has been reported also kidney complication in FCS, but the data are sparse. To this aim, we have retrospectively evaluated the spontaneous variation of platelet counts and Kidney impairment in a cohort of patients with FCS. Methods: Single-center retrospective cohort study on 20 FCS patients included in the LIPIGEN. Medical charts have been revised to collect retrospectively information on kidney function in a cohort of patients with FCS. Results: Across the study population, the median PLT count was 187,225 platelet/mcL. The median on treatment TG levels in the whole cohort was 1309 mg/dl. During follow-up, 8 (44.4%) patients experienced at least one episode of mild and 1 (5%) of moderate thrombocytopenia. None had severe thrombocytopenia. Mean triglycerides do not significantly predict mean platelet values. However, when considering a multivariate model including mean triglycerides, sex, the presence of hepatic steatosis and age we found that male sex and the presence of ultrasound estimated hepatic steatosis were associated with significantly lower platelet (respectively β-0,473, P=0,044 and β-0,469, P=0,048). Age was of borderline statistical significance (β-0,388, P=0,087). Across the study population, the median GFR values was 99.5 ml/min. Median eGFR was significantly associated with history of hypertension (β-0,508, P=0,031). Overall, proteinuria occurred in 5 (25%) patients, and it did not associate with hypertension, diabetes, age, sex nor triglyceride levels. Four (20.0%) patients meet the criteria of hyperfiltration whereas 3 (15.0%) were exhibiting an eGFR below 90 ml/min. Among hyperfiltrating, two had also proteinuria in at least one occasion during life. One patient with eGFR below 90 ml/min and proteinuria had a biopsy-proven diagnosis of glomerulonephritis. Overall, the impairment in kidney function was independent from age, diabetes, hypertension, median TGs, AP, sex. Conclusions: The present analysis confirmed that thrombocytopenia and kidney impairment might be a clinical characteristics of FCS phenotype. Further studies in larger cohort are needed to better clarify if kidney disease and thrombocytopenia might be a hallmark of FCS in broader population and understand the potential patho-physiological mechanism.

Thalassemia and Nanotheragnostics: Advanced Approaches for Diagnosis and Treatment

Thalassemia is a monogenic autosomal recessive disorder caused by mutations, which lead to abnormal or reduced production of hemoglobin. Ineffective erythropoiesis, hemolysis, hepcidin suppression, and iron overload are common manifestations that vary according to genotypes and dictate, which diagnosis and therapeutic modalities, including transfusion therapy, iron chelation therapy, HbF induction, gene therapy, and editing, are performed. These conventional therapeutic methods have proven to be effective, yet have several disadvantages, specifically iron toxicity, associated with them; therefore, there are demands for advanced therapeutic methods. Nanotechnology-based applications, such as the use of nanoparticles and nanomedicines for theragnostic purposes have emerged that are simple, convenient, and cost-effective methods. The therapeutic potential of various nanoparticles has been explored by developing artificial hemoglobin, nano-based iron chelating agents, and nanocarriers for globin gene editing by CRISPR/Cas9. Au, Ag, carbon, graphene, silicon, porous nanoparticles, dendrimers, hydrogels, quantum dots, etc., have been used in electrochemical biosensors development for diagnosis of thalassemia, quantification of hemoglobin in these patients, and analysis of conventional iron chelating agents. This review summarizes the potential of nanotechnology in the development of various theragnostic approaches to determine thalassemia-causing gene mutations using various nano-based biosensors along with the employment of efficacious nano-based therapeutic procedures, in contrast to conventional therapies.

Distribution of Exonic Variants in Glycogen Synthesis and Catabolism Genes in Late Onset Pompe Disease (LOPD)

Pompe disease (PD) is a monogenic autosomal recessive disorder caused by biallelic pathogenic variants of the GAA gene encoding lysosomal alpha-glucosidase; its loss causes glycogen storage in lysosomes, mainly in the muscular tissue. The genotype-phenotype correlation has been extensively discussed, and caution is recommended when interpreting the clinical significance of any mutation in a single patient. As there is no evidence that environmental factors can modulate the phenotype, the observed clinical variability in PD suggests that genetic variants other than pathogenic GAA mutations influence the mechanisms of muscle damage/repair and the overall clinical picture. Genes encoding proteins involved in glycogen synthesis and catabolism may represent excellent candidates as phenotypic modifiers of PD. The genes analyzed for glycogen synthesis included UGP2, glycogenin (GYG1-muscle, GYG2, and other tissues), glycogen synthase (GYS1-muscle and GYS2-liver), GBE1, EPM2A, NHLRC1, GSK3A, and GSK3B. The only enzyme involved in glycogen catabolism in lysosomes is α-glucosidase, which is encoded by GAA, while two cytoplasmic enzymes, phosphorylase (PYGB-brain, PGL-liver, and PYGM-muscle) and glycogen debranching (AGL) are needed to obtain glucose 1-phosphate or free glucose. Here, we report the potentially relevant variants in genes related to glycogen synthesis and catabolism, identified by whole exome sequencing in a group of 30 patients with late-onset Pompe disease (LOPD). In our exploratory analysis, we observed a reduced number of variants in the genes expressed in muscles versus the genes expressed in other tissues, but we did not find a single variant that strongly affected the phenotype. From our work, it also appears that the current clinical scores used in LOPD do not describe muscle impairment with enough qualitative/quantitative details to correlate it with genes that, even with a slightly reduced function due to genetic variants, impact the phenotype.

Hematological and genetic profiles of persons with co-inherited heterozygous β-thalassemia and supernumerary α-globin genes.

Thalassemias are common monogenic autosomal recessive hemoglobin disorders. The usually asymptomatic heterozygotes (β-thalassemia traits, βTT) may rarely develop non-transfusion-dependent-thalassemia (NTDT) due to co-inheritance of supernumerary α-globin genes. Literature on phenotypic/genotypic features of these rare combinations is limited. We studied the demographic, clinical, and laboratory data from 47 persons with co-inherited βTT + supernumerary α-globin genes. HBB mutations were tested for by ARMS-PCR and/or Sanger sequencing, ααα(anti3.7) /ααα(anti4.2) and deletional α-thalassemia testing by multiplex gap-PCRs, and Xmn1G γ genotyping by PCR-RFLP. The 47 cases comprised 0.08% of 61 010 hemoglobinopathy screenings during the study period. Mean age was 31.9± 14.7 years (range 5.5-83 years), with 57.4% males. Thirty (63.8%) had NTDT-phenotype, 16 (34%) were asymptomatic/minimally symptomatic, and 1 became transfusion-dependent at the age of 20 years. Anemia/pallor and jaundice were the commonest complaints (76% each); 40% had required blood transfusions. Twenty-one had splenomegaly, 14 had hepatomegaly. Mean hemoglobin was 9.0± 1.9g/dl (range 4.0-13.0). HbA2 was 5.1± 0.7% (3.4%-6.3%) and HbF% 4.2± 3.2% (0.5%-18.4%). Forty-four (93.6%) had αααanti3.7 , while 3 (6.4%) had αααanti4.2 triplications. HBB:c.92+5G>C (47%), HBB:c.27_28insG (14.9%), and HBB:c.47G>A (8.5%) were the commonest β-globin mutations. One case showed HBB:c.-138C>T (β++ ), while the rest had β0 or severe-β+ mutations. Symptomatic cases had significantly lower hemoglobins and higher HbF% than asymptomatic ones. This largest Indian and globally second-largest study reports the βTT + ααα4.2 state for the first time in such genotypically-complex Indian cases. Supernumerary α-genes should be suspected in all βTT with disproportionate clinical symptoms, mild-to-moderately elevated HbF, and unexplained anisopoikilocytosis.

Short communication: Prevalence of deleterious variants causing recessive disorders in Italian Chianina, Marchigiana and Romagnola cattle

In the last two decades, the molecular cause of six monogenic autosomal recessive disorders has been identified in native Italian beef cattle: two different ATP2A1 variants for the pseudomyotonia congenita, the first in Chianina and Romagnola (PMT1) and the second in Romagnola (PMT2); a KDM2B variant for the paunch calf syndrome (PCS) in Marchigiana and Romagnola; a NID1 variant for the congenital cataract (CC) in Romagnola; a LAMB1 variant for the hemifacial microsomia (HFM) in Romagnola; an ABCA12 variant for the ichthyosis fetalis (IF) in Chianina and a FA2H variant for the ichthyosis congenita (IC) in Chianina. The aim of this study was to evaluate the potential impact of these disorders in the affected Italian populations. For this purpose, 3331 Chianina, 2812 Marchigiana and 1680 Romagnola bulls born in the last 40 years were considered. The allelic frequency (AF) of the variant for PMT1 was 1.0% in Romagnola, 4.6% in Marchigiana and 5.9% in Chianina. The AF of the variant for PMT2 was 3.3% in Romagnola and 0% in the other two breeds. The AF of the variant for PCS was 11.7% in Romagnola, 2.0% in Marchigiana and 0% in Chianina. The AF of the variants for CC, HFM, IF and IC resulted below 3%, being the variants detected only in the breed populations in which they were previously reported. Considering a selected male population in the single breed, Chianina showed carrier prevalence of 11.9% for PMT1, 7.7% for IC and 6.4% for IF. Romagnola showed carrier prevalence of 23.4% for PCS, 6.7% for PMT2, 4.1% for HFM, 3.2% for CC and 2.0% for PMT1. Marchigiana showed carrier prevalence of 9.1% for PMT1 and 4.0% for PCS. With respect to the Romagnola cattle, the concerning presence of a total of five defect alleles in the population hampers a general approach based on the prevention of carriers from artificial insemination. However, identification of carriers may allow conscious mating to prevent the risk of homozygous descendants as well as the spread of heterozygous offspring. Therefore, systematic genotyping for all seven known harmful alleles is recommended to prevent risk mating between carriers, in particular to avoid the occurrence of affected offspring.

State of the Art on Approved Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Modulators and Triple-Combination Therapy.

Cystic fibrosis (CF) is the most common life-limiting inherited disease in Caucasian populations, affecting approximately 80,000 people worldwide. CF is a complex multi-organ monogenic autosomal recessive disorder caused by a mutation in cystic fibrosis transmembrane conductance regulator (CFTR) gene. Since the discovery of the CFTR gene in 1989, more than 2000 mutations have been identified so far and about 240 can cause CF. Until recently, the treatment for CF was aimed to prevent and manage the manifestations of CFTR dysfunction, primarily recurrent pulmonary infections and pancreatic exocrine failure. Over the past few decades, the therapeutic approach to CF has been revolutionized by the development of a new class of small molecules called CFTR modulators that target specific defects caused by mutations in the CFTR gene. CFTR modulators have been shown to change profoundly the clinical course of the CF, leading to meaningful improvements in the lives of a large proportion of people of CF heterozygous for F508del, especially if started in young children. Further studies are needed to extend the use of triple CFTR modulation therapy also for young children in order to prevent the irreversible effects of the disease and for patients with very rare mutations with a personalized approach to treatment.

Unmet needs and evolving treatment for limb girdle muscular dystrophies.

Limb-girdle muscular dystrophies (LGMDs) represent a major group of muscle disorders. Treatment is sorely needed and currently expanding based on safety and efficacy adopting principles of single-dosing gene therapy for monogenic autosomal recessive disorders. Gene therapy has made in-roads for LGMD and this review describes progress that has been achieved for these conditions. This review first provides a background on the definition and classification of LGMDs. The major effort focuses on progress in LGMD gene therapy, from experimental studies to clinical trials. The disorders discussed include the LGMDs where the most work has been done including calpainopathies (LGMD2A/R1), dysferlinopathies (LGMD2B/R2) and sarcoglycanopathies (LGMD2C/R5, LGMD2D/R3, LGMD2E/R4). Early success in clinical trials provides a template to move the field forward and potentially apply emerging technology like CRISPR/Cas9 that may enhance the scope and efficacy of gene therapy applied to patient care.

918-P: Predicting the Onset of APECED Diabetes

Background: Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare monogenic autosomal recessive disorder and diabetes (DM) one of its rare and less studied manifestations. Determinants of time to onset and clinical progression to DM seem currently unpredictable. Materials and Methods: We explored change in pre-diagnosis (dg) glycemic parameters (glucose, insulin, C-peptide), including 60’ intravenous glucose tolerance tests (ivGTT) and homeostasis indices (HOMA-β, -IR) over 20 years (y) with descriptive statistics. Fractional glucose turnover rate (KG) during ivGTT was calculated as 0.693/T1/2Gluc*100 with Pearson correlation coefficient (r) and 2-sided p value. Results: Between 1972 and 1996, 68 ivGTTs were conducted in 13 pediatric and adult individuals with APECED and DM. The mean age (SD) at DM dg was 27.78y (11.73) among those 22% of our cohort (n=100) with DM. Including one man with ‘latent DM’, with no clinical DM symptoms 20y post-dg. HbA1c was rarely measured, fasting plasma glucose (FPG) values were normoglycemic prior and up to DM dg: mean (SD) FPG 4.4 (0.6) mmol/l (-20y to -6 months [m]) and 5.7 (0.9) mmol/l (<6m to dg). Mean 60’ glucose values were only elevated for those with <6m to dg: 12.1 (0.7) mmol/l. Hyperinsulinemia was present 5-20y prior to dg while rapid 1st phase insulin secretion (combined 1+3 min value; normal >46 mIU/ml) was lost or delayed in some, but not all, 5y prior to dg. Up to and at dg, adequate fasting insulin (>2 mIU/ml) and C-peptide (>0.5 ng/ml) production was observed in most (85%) patients. KG displayed intra- and inter-individual variability, was normal (>1.2%/min) in latent DM, while it predicted DM onset over time (-20y to dg): r= -0.568 (p= 4E-06). Neither HOMA indices were sensitive enough to detect any change over time. Conclusion: Identification of reduced glucose removal rate over time, indicative of increased peripheral insulin resistance in the presence of pre-diagnostic hyperinsulinemia, provides first insights into progression of atypical diabetes in APECED patients. Disclosure P. M. Paldanius: Consultant; Self; UPM Biomedicals, Speaker’s Bureau; Self; Novartis AG. O. Makitie: None. S. Laakso: None.

Detection of the Brachyspina mutation in Uruguayan Holstein cows using real time PCR and melting curve analysis

ABSTRACT: Brachyspina syndrome (BS) is a rare monogenic autosomal recessive hereditary disorder of the Holstein Fresian breed caused by a deletion of 3.3Kb in the Fanconi anemia complementation group I (FANCI) gene on BTA-21, which leads to a frame-shift and premature stop codon. Some of the consequences of BS are the reduction of the fertility rate and milk production. This study developed a simple, sensitive, rapid cost- effective assay method based on real time PCR and melting curve analysis for the detection of BS carrier animals. Sixty-eight normal homozygous and four heterozygous carrier genotypes were detected and confirmed through traditional PCR- electrophoresis analysis. We concluded that the assay we have developed proved to be a reliable, highly precise and low-cost tool, which could be used to monitor the presence of the BS mutation in uruguayan Holstein breed.

Pharmacological approaches for targeting cystic fibrosis nonsense mutations

Cystic fibrosis (CF) is a monogenic autosomal recessive disorder. The clinical manifestations of the disease are caused by ∼2,000 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) protein. It is unlikely that any one approach will be efficient in correcting all defects. The recent approvals of ivacaftor, lumacaftor/ivacaftor and elexacaftor/tezacaftor/ivacaftor represent the genesis of a new era of precision combination medicine for the CF patient population. In this review, we discuss targeted translational readthrough approaches as mono and combination therapies for CFTR nonsense mutations. We examine the current status of efficacy of translational readthrough/nonsense suppression therapies and their limitations, including non-native amino acid incorporation at PTCs and nonsense-mediated mRNA decay (NMD), along with approaches to tackle these limitations. We further elaborate on combining various therapies such as readthrough agents, NMD inhibitors, and corrector/potentiators to improve the efficacy and safety of suppression therapy. These mutation specific strategies that are directed towards the basic CF defects should positively impact CF patients bearing nonsense mutations.

Genetic activation of Nrf2 reduces cutaneous symptoms in a murine model of Netherton syndrome.

ABSTRACTNetherton syndrome is a monogenic autosomal recessive disorder primarily characterized by the detachment of the uppermost layer of the epidermis, the stratum corneum. It results from mutations in the SPINK5 gene, which codes for a kallikrein inhibitor. Uncontrolled kallikrein activity leads to premature desquamation, resulting in a severe epidermal barrier defect and subsequent life-threatening systemic infections and chronic cutaneous inflammation. Here, we show that genetic activation of the transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nfe2l2/Nrf2) in keratinocytes of Spink5 knockout mice, a model for Netherton syndrome, significantly alleviates their cutaneous phenotype. Nrf2 activation promoted attachment of the stratum corneum and concomitant epidermal barrier function, and reduced the expression of pro-inflammatory cytokines such as tumor necrosis factor α and thymic stromal lymphopoietin. Mechanistically, we show that Nrf2 activation induces overexpression of secretory leukocyte protease inhibitor (Slpi), a known inhibitor of kallikrein 7 and elastase 2, in mouse and human keratinocytes in vivo and in vitro, respectively. In the Spink5-deficient epidermis, the upregulation of Slpi is likely to promote stabilization of corneodesmosomes, thereby preventing premature desquamation. Our results suggest pharmacological NRF2 activation as a promising treatment modality for Netherton syndrome patients.This article has an associated First Person interview with the first author of the paper.

Delay in the Diagnosis of APECED: A Case Report and Review of Literature from Iran

ABSTRACTAutoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) syndrome is a rare monogenic autosomal recessive disorder caused by biallelic mutations in the AIRE (autoimmune regulator) gene. Patients with APECED present with heterogeneous endocrine and non-endocrine manifestations. In this study, we report an Iranian patient who presented with Addison disease, chronic mucocutaneous candidiasis, alopecia totalis, keratopathy and asplenia treated as an isolated endocrinopathy for 25 years. In the adulthood, the diagnosis of APECED was made by genetic analysis which demonstrated homozygous nonsense p.R257* (c.769C>T) mutation of AIRE. APECED has been shown to be frequent in some ethnicities including Iranian Jews. Therefore, we reviewed 39 Iranian APECED patients published in the literature. We found that most of the Iranian patients were of Jewish ethnic background and presented hypoparathyroidism, adrenal insufficiency, and candidiasis as the main clinical manifestation.

Gene and Base Editing as a Therapeutic Option for Cystic Fibrosis-Learning from Other Diseases.

Cystic fibrosis (CF) is a monogenic autosomal recessive disorder caused by mutations in the CFTR gene. There are at least 346 disease-causing variants in the CFTR gene, but effective small-molecule therapies exist for only ~10% of them. One option to treat all mutations is CFTR cDNA-based therapy, but clinical trials to date have only been able to stabilise rather than improve lung function disease in patients. While cDNA-based therapy is already a clinical reality for a number of diseases, some animal studies have clearly established that precision genome editing can be significantly more effective than cDNA addition. These observations have led to a number of gene-editing clinical trials for a small number of such genetic disorders. To date, gene-editing strategies to correct CFTR mutations have been conducted exclusively in cell models, with no in vivo gene-editing studies yet described. Here, we highlight some of the key breakthroughs in in vivo and ex vivo gene and base editing in animal models for other diseases and discuss what might be learned from these studies in the development of editing strategies that may be applied to cystic fibrosis as a potential therapeutic approach. There are many hurdles that need to be overcome, including the in vivo delivery of editing machinery or successful engraftment of ex vivo-edited cells, as well as minimising potential off-target effects. However, a successful proof-of-concept study for gene or base editing in one or more of the available CF animal models could pave the way towards a long-term therapeutic strategy for this disease.

Modern pathogenesis-based methods and development of new gene and cell-based methods for cystic fibrosis treatment

Cystic fibrosis is a monogenic autosomal recessive disorder caused by mutations in CFTR gene. Until recent days, cystic fibrosis therapy was limited to symptomatic treatment of respiratory infections and malabsorption. In last years pathogenetic therapy of the disease received significant progress and premises for development of new methods of gene therapy came into sight. In the review, modern methods of cystic fibrosis treatment are considered, some of them are already used in the clinic (pathogenesis-based therapy with CFTR modulators), while the other part is only developing (gene therapy, including genome editing and cell therapy).

A splice site variant in the SUV39H2 gene in Greyhounds with nasal parakeratosis.

Hereditary nasal parakeratosis (HNPK), described in the Labrador Retriever breed, is a monogenic autosomal recessive disorder that causes crusts and fissures on the nasal planum of otherwise healthy dogs. Our group previously showed that this genodermatosis may be caused by a missense variant located in the SUV39H2 gene encoding a histone 3 lysine 9 methyltransferase, a chromatin modifying enzyme with a potential role in keratinocyte differentiation. In the present study, we investigated a litter of Greyhounds in which six out of eight puppies were affected with parakeratotic lesions restricted to the nasal planum. Clinically and histologically, the lesions were comparable to HNPK in Labrador Retrievers. Whole genome sequencing of one affected Greyhound revealed a 4-bp deletion at the 5'-end of intron 4 of the SUV39H2 gene that was absent in 188 control dog and three wolf genomes. The variant was predicted to disrupt the 5'-splice site with subsequent loss of SUV39H2 function. The six affected puppies were homozygous for the variant, whereas the two non-affected littermates were heterozygous. Genotyping of a larger cohort of Greyhounds revealed that the variant is segregating in the breed and that this breed might benefit from genetic testing to avoid carrier × carrier matings.

New treatments targeting the basic defects in cystic fibrosis

Cystic fibrosis (CF) is a monogenic autosomal recessive disorder affecting around 75,000 individuals worldwide. It is a multi-system disease but the main morbidity and mortality is caused by chronic lung disease. Due to newborn screening, a multidisciplinary approach to care and intensive symptomatic treatment, the prognosis has dramatically improved over the last decades and there are currently more adults than children in many countries. However, CF is still a very severe disease with a current median age of life expectancy in the fourth decade of life. The disease is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene which encodes the CFTR protein, a protein kinase A-activated ATP-gated anion channel that regulates the transport of electrolytes such as chloride and bicarbonate. More than 2000 mutations have been reported, although not all of these have functional consequences. An enormous research effort and progress has been made in understanding the consequences of these mutations on the CFTR protein structure and function, and this has led to the approval of two new drug therapies that are able to bind to defective CFTR proteins and partially restore their function. They are mutation-specific therapies and available at present for specific mutations only. They are the first personalized medicine for CF with a possible disease-modifying effect. A pipeline of other compounds is under development with different mechanisms of action. It is foreseeable that new combinations of compounds will further improve the correction of CFTR function. Other strategies including premature stop codon read-through drugs, antisense oligonucleotides that correct the basic defect at the mRNA level or gene editing to restore the defective gene as well as gene therapy approaches are all in the pipeline. All these strategies are needed to develop disease-modifying therapies for all patients with CF.

Гепатолентикулярная дегенерация: трудности диагностики (случаи из практики)

The article deals with severe hereditary disease – hepatolenticular degeneration (Wilson–Konovalov disease). Hepato-lenticular degeneration is a monogenic autosomal recessive genetic disorder. Pathogenetically, it is a genetic disorder of copper metabolism when copper accumulates in excessive amounts in target organs, primarily in the liver. More commonly it manifests at young age and, when untreated, progresses rapidly to death. At the same time, hepatolenticular degeneration is one of a few of hereditary disease for which an effective pathogenetic therapy with copper-eliminating medications has been developed to reduce the amount of dietary copper and to remove its excess from the body. The risk factors of unfavourable type of decease development are: the severity of clinical aspects at the time of diag-nostics in neurological stage, period of the delay of the copper-eliminate therapy prescription and the degree of mind disorder. The prognostication on hepatolenticular degeneration depends on the duration of the decease, time of the therapy beginning and the compliance to it.We report about two clinical observations of hepatolenticular degeneration, demonstrating the necessity to use the full complex of clinical-laboratorial and instrumental analysis in all cases of developing motor extrapyramidal defects, combined with psychiatric disorders and pathology of internal organs. This work proved that it is necessary to evaluate all symptoms in the dynamics of disease course and that symptoms signaling about pathology of copper metabolism should not be ignored, and paying attention only to some of the indicants is not advised.