Recessive Disease Research Articles

Chédiak Higashi Syndrome -A hematological Diagnosis and Review of Literature

Chediak Higashi Syndrome is a rare autosomal recessive disease come in picture early in age, mainly paediatric group and is fatal. In India, till the year 2000, only five cases have been reported. In this study ,we present all the cases reported in India, their clinical presentation, CBC ,PBS ,Bone marrow findings, skin biopsy or hair study (if performed) and their correlation to see the accelerated phase of the disease and approach to the management. Determined peripheral blood smear examination is the key to arrest the diagnosis of Chediak Higashi Syndrome in developing country like India, defining it is the most easiest, quickest, cheap, easily available investigation in our country.

Genetic tool used to diagnose achromatopsia: first case report from India

BackgroundAchromatopsia is an autosomal recessive disease characterized by poor visual acuity, lack of color vision, nystagmus, and marked photophobia. The symptoms can be extremely disabling, and at present, there is no cure available. Mutations in the CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6 genes have been identified as associated with this disease. The genetic approach for these patients is currently an important issue, and gene therapy is an ongoing therapeutic option already being studied in clinical trials.Case presentationWe report the case of two siblings (8 and 5 years old) affected by achromatopsia. They carry compound heterozygous mutations in the CNGA3 gene at positions 1306 and 1279 in exon 8 (c.1306C > T, p.Arg436Trp and c.1279C > T, p.Arg427Cys). The parents were found to have one of the variants in a heterozygous condition. This is the first reported case of achromatopsia in India.ConclusionThis report emphasizes the importance of genetic testing in such patients, which can aid not only in the diagnosis and management but also in providing counseling to parents regarding the significance of prenatal diagnosis in future pregnancies, helping them make informed choices. Due to its variable presentation, the diagnosis of achromatopsia may be challenging, and exome sequencing has proven to be a crucial diagnostic tool.

A novel PKHD1 splicing variant identified in a fetus with autosomal recessive polycystic kidney disease.

Objective: Variants of the polycystic kidney and hepatic disease 1 (PKHD1) gene are associated with autosomal recessive polycystic kidney disease (ARPKD). This study aimed to identify the genetic causes in a Chinese pedigree with ARPKD and design a minigene construct of the PKHD1 gene to investigate the impact of its variants on splicing. Methods: Umbilical cord samples from the proband and peripheral blood samples from his parents were collected, and genomic DNA was extracted for whole-exome sequencing (WES). Bioinformatic analysis was used to identify potential genetic causes, and Sanger sequencing confirmed the existence of variants within the pedigree. A minigene assay was performed to validate the effects of an intronic variant on mRNA splicing. Results: Two variants, c.9455del (p.N3152Tfs*10) and c.2408-13C>G, were identified in the PKHD1 gene (NM_138694.4) by WES; the latter has not been previously reported. In silico analysis predicted that this intronic variant is potentially pathogenic. Bioinformatic splice prediction tools revealed that the variant is likely to strongly impact splice site function. An in vitro minigene assay revealed that c.2408-13C>G can cause aberrant splicing, resulting in the retention of 12 bp of intron 23. Conclusion: A novel pathogenic variant of PKHD1, c.2408-13C>G, was found in a fetus with ARPKD, which enriches the variant spectrum of the PKHD1 gene and provides a basis for genetic counseling and the diagnosis of ARPKD. Minigenes are optimal to determine whether intron variants can cause aberrant splicing.

Long-term administration of intravenous Trappsol® Cyclo™ (HP-β-CD) results in clinical benefits and stabilization or slowing of disease progression in patients with Niemann-Pick disease type C1: Results of an international 48-week Phase I/II trial

BackgroundNiemann-Pick disease type C (NPC) is a rare, fatal, pan-ethnic, autosomal recessive lysosomal storage disease characterized by progressive major organ failure and neurodegeneration. Preclinical studies confirmed a critical role of systemically administered hydroxypropyl-β-cyclodextrin (HP-β-CD; Trappsol® Cyclo™) in cholesterol metabolism and homeostasis in peripheral tissues of the body, including the liver, and in the central nervous system (CNS). Herein, the pharmacokinetics (PK), safety, and efficacy of HP-β-CD, and biomarkers of NPC were assessed in pediatric and adult patients with NPC1. MethodsThis was a multicenter, Phase I/II, randomized, double-blind, parallel-group, 48-week study (ClinicalTrials.gov identifier NCT02912793) to compare the PK of three different single intravenous (IV) doses of HP-β-CD in pediatric and adult patients with NPC1 and to evaluate the efficacy and tolerability of three different dosages of HP-β-CD in patients with NPC1 after long-term treatment. Twelve patients aged at least 2 years (2–39 years of age) with a confirmed diagnosis of NPC1 were randomized to receive one of three IV doses of HP-β-CD (1500 mg/kg, 2000 mg/kg, or 2500 mg/kg) every 2 weeks for 48 weeks. All patients received HP-β-CD; there was no placebo or other control. PK testing of plasma and cerebrospinal fluid (CSF) was at set times after the first infusion. Pharmacodynamic assessments included biomarkers of cholesterol metabolism (synthesis and breakdown products), N-palmitoyl-O-phosphocholineserine (PPCS), and specific biomarkers of CSF neurodegeneration (including total Tau), CNS inflammation (glial fibrillary acidic protein [GFAP] and tumor necrosis factor α [TNFα]), CNS cholesterol metabolism (24S-hydroxycholesterol) and inflammatory markers. Efficacy measures included clinical disease severity, neurologic symptoms, and clinical impressions of improvement. Safety assessment included physical examination, vital signs, clinical safety laboratory assessment and adverse events (AEs). ResultsNine patients completed the study, 2 in the 1500 mg/kg group, 4 in the 2000 mg/kg group and 3 in the 2500 mg/kg group. Three patients (all in the 1500 mg/kg group) discontinued the study because of either physician decision/site Principal Investigator (PI) discretion, withdrawal by subject/patient/parent/guardian, or other non-safety reasons. In 5 patients who underwent serial lumbar punctures, HP-β-CD was detected in the CSF. Of the 9 patients who completed the study, 8 (88.9%) improved in at least two domains of the 17-Domain Niemann-Pick disease Type C-Clinical Severity Scale (17D-NPC-CSS), and 6 of these patients improved in at least one domain viewed by patients and their caregivers to be key to quality of life, namely, speech, swallow, fine and gross motor skills, and cognition. Of the 9 patients who completed the study, 7 were viewed by their treating physicians as having improved to some degree at the end of the study, and 2 remained stable; both outcomes are highly relevant in a progressive neurodegenerative disease. Some patients and families reported improvement in quality of life.All three doses of HP-β-CD were well tolerated overall, with most treatment-emergent adverse events transient, mild-to-moderate in nature, and considered by the site PIs to be not related to study drug. InterpretationThis 48-week trial is the longest to date to evaluate the safety, tolerability, and efficacy across multiple clinical endpoints of IV administration of Trappsol® Cyclo™ (HP-β-CD) in NPC1 patients. In pediatric and adult patients with NPC, Trappsol® Cyclo™ IV improved clinical signs and symptoms and was generally well tolerated. The findings presented here demonstrate a favorable benefit-risk profile and support the global pivotal trial now underway to evaluate the long-term treatment benefits and the potential of Trappsol® Cyclo™ as a disease-modifying treatment in this patient population.

Genetic analysis and functional study of a novel ABCG5 mutation in sitosterolemia with hematologic disease

Sitosterolemia is a rare autosomal recessive hereditary disease caused by loss-of-function genetic mutations in either ATP-binding cassette subfamily G member 5 or member 8 (ABCG5 or ABCG8). Here, we investigate novel variants in ABCG5 and ABCG8 that are associated with the sitosterolemia phenotype. We describe a 32-year-old woman with hypercholesterolemia, tendon and hip xanthomas, autoimmune hemolytic anemia and macrothrombocytopenia from early life, which make us highly suspicious of the possibility of sitosterolemia. A novel homozygous variant in ABCG5 (c.1769C>A, p.S590X) was identified by genomic sequencing. We also examined the lipid profile, especially plant sterols levels, using gas chromatography-mass spectrometry. Functional studies, including western blotting and immunofluorescence staining, showed that the nonsense mutation ABCG5 1769C>A hinders the formation of ABCG5 and ABCG8 heterodimers and the function of transporting sterols. Our study expands the knowledge of variants in sitosterolemia and provides diagnosis and treatment recommendations.

GAA deficiency disrupts distal airway cells in Pompe disease.

Pompe disease is an autosomal recessive glycogen storage disease caused by mutations in the gene that encodes acid alpha-glucosidase (GAA)-an enzyme responsible for hydrolyzing lysosomal glycogen. GAA deficiency results in systemic lysosomal glycogen accumulation and cellular disruption. Glycogen accumulation in skeletal muscles, motor neurons, and airway smooth muscle cells is known to contribute to respiratory insufficiency in Pompe disease. However, the impact of GAA deficiency on the distal alveolar type 1 and type 2 cells (AT1 and AT2) has not been evaluated. AT1 cells rely on lysosomes for cellular homeostasis so that they can maintain a thin barrier for gas exchange, whereas AT2 cells depend on lysosome-like structures (lamellar bodies) for surfactant production. Using a mouse model of Pompe disease, the Gaa-/- mouse, we investigated the consequences of GAA deficiency on AT1 and AT2 cells using histology, pulmonary function and mechanics, and transcriptional analysis. Histological analysis revealed increased accumulation of lysosomal-associated membrane protein 1 (LAMP1) in the Gaa-/- mice lungs. Furthermore, ultrastructural examination showed extensive intracytoplasmic vacuoles enlargement and lamellar body engorgement. Respiratory dysfunction was confirmed using whole body plethysmography and forced oscillometry. Finally, transcriptomic analysis demonstrated dysregulation of surfactant proteins in AT2 cells, specifically reduced levels of surfactant protein D in the Gaa-/- mice. We conclude that GAA enzyme deficiency leads to glycogen accumulation in the distal airway cells that disrupts surfactant homeostasis and contributes to respiratory impairments in Pompe disease.NEW & NOTEWORTHY This research highlights the impact of Pompe disease on distal airway cells. Prior to this work, respiratory insufficiency in Pompe disease was classically attributed to pathology in respiratory muscles and motor neurons. Using the Pompe mouse model, we note significant pathology in alveolar type 1 and 2 cells with reductions in surfactant protein D and disrupted surfactant homeostasis. These novel findings highlight the potential contributions of alveolar pathology to respiratory insufficiency in Pompe disease.

New-born screening of metabolites with liquid chromatography-mass spectrometry and gas chromatography–mass spectrometry: a metabolic and molecular signatures methyl malonic aciduria with combined oxidative phosphorylation deficiency-10: a rare case report

An uncommon autosomal recessive organic acid disease is malonic aciduria. This disease may be easily identified and included in the NBS programmes by means of the widespread use of tandem mass spectrometry’s in the study of the amino acid/acylcarnitine profile using dried blood spots (DBS) for newborn screening. In Tamil Nadu, we reported the first screened and diagnosed with malonic aciduria by newborn screening (NBS) in early neonatal period. The patient possesses a malonyl-CoA decarboxylase genetic variation not previously described. This disease should be distinguished from a related malonic and methylmalonic aciduria problem. Malonic aciduria's clinical phenomenology varies and pathogenesis is not completely known. The proper treatment regimen, nutritional therapy or frequent follow-up to these individuals are not guided or recommended. The majority of current treatment data is based on a single research or case report.

Variability of clinical manifestations in the child with Roifman syndrome

Introduction. Roifman syndrome is a rare hereditary autosomal recessive disease, often associated with primary immunodeficiency and spondyloepiphyseal dysplasia. The cause of the disease is a splicing disorder due to a mutation of the RNU4ATAC gene with the formation of an incorrect protein structure, which in turn leads to clinical polymorphism.
 Purpose: demonstration of own clinical observation of the 5-year girl with Roifman syndrome.
 Materials and methods. An analysis of the literature on the stigmas of dysembriogenesis, clinical manifestations, changes in the immune system that determine the formation of Roifman syndrome was carried out.
 Results. The features of the course and variability of manifestations in the particular patient with Roifman syndrome are described. The variety and non-specificity of clinical symptoms in Roifman syndrome in the 5-year girl is shown. Timely diagnosis after complete sequencing by Sanger made it possible to identify a complex heterozygous mutation in the RNU4ATAC gene and start adequate therapy.

BI31 Hereditary haemochromatosis: a risk factor for nonmelanoma skin cancer?

Abstract Hereditary haemochromatosis (HH) is an autosomal recessive disease resulting in excessive levels of iron. In a recent study, in a US population of 448 patients diagnosed with HH, a positive association between HH and nonmelanoma skin cancers (NMSCs) was observed (Pan CX, Yang K, Lau CB et al. Non-melanoma skin cancer in patients with hereditary hemochromatosis: a case–control study. J Am Acad Dermatol 2023; 88:692–4). The authors also reported that, among those who required more frequent venesection, the risk of basal cell carcinoma (BCC) was particularly elevated. In terms of the possible pathomechanism, the authors noted that oxidative stress represents a key component in the pathogenesis of both HH and BCC. Ireland has the highest prevalence of HH in the world, with research suggesting approximately 1 in 83 people is predisposed. For this reason, a study was undertaken to determine if a similar association could be observed in an Irish population. A single-centre retrospective cross-sectional analysis was undertaken on a database of patients with haemochromatosis attending the venesection department of a tertiary referral centre over 25 years (1997–2022). All histologically diagnosed NMSCs within this patient group were then recorded. Ethical approval was granted by the local hospital ethics committee. There were a total 1480 patients in the database, 65% Male (n = 956). Five were excluded due to insufficient data. Thus, 1475 patients were analysed, 64% male (n = 949). The mean current age was 60 years (range: 19–100). Only 52/1475 patients (3.5%) had a histologically diagnosed NMSC, 52% male (n = 27). HH genetic mutation: C282Y homozygous (n = 29); H63D homozygous (n = 5); C282Y/H63D compound heterozygous (n = 11); and data not recorded (n = 7). Mean ferritin at HH diagnosis 575 (range: 0–8413). Forty-three patients were diagnosed with a BCC, 58% male (n = 25), with a total of 94 BCCs. Mean age was 67 years at first NMSC diagnosis. Histological classification: nodular (n = 48); superficial (n = 19); unclassified (n = 18); infiltrative (n = 5); micronodular (n = 3); and basosquamous (n = 1). Eleven patients were diagnosed with a squamous cell carcinoma (SCC), with a total of 21 SCCs. This study had limitations. It was a single-centre, retrospective study analysing only histologically confirmed NMSCs. It is acknowledged that a small proportion of NMSCs may be diagnosed clinically, specifically superficial BCCs without histological confirmation. Only records with histology available in our institution were recorded, and it is possible that NMSCs were excised in other institutions, potentially leading to an under-representation of NMSC incidence. The proportion of patients diagnosed with NMSCs in this cohort was relatively low, in contrast to the findings reported by Pan et al. This study indicates that HH is unlikely to represent an independent risk factor.

The gene therapy for corneal pathology with novel nonsense cystinosis mouse lines created by CRISPR Gene Editing

PurposeCystinosis is an autosomal recessive lysosomal storage disease (LSDs) caused by mutations in the gene encoding cystinosin (CTNS) that leads to cystine crystal accumulation in the lysosome that compromises cellular functions resulting in tissue damage and organ failure, especially in kidneys and eyes. However, the underlying molecular mechanism of its pathogenesis remains elusive. Two novel mice lines created via CRISPR are used to examine the pathogenesis of cystinosis in the kidney and cornea and the treatment efficacy of corneal pathology using self-complimentary Adeno-associated viral (scAAV-CTNS) vector. MethodsThe CRISPR technique generated two novel cystinotic mouse lines, Ctnsis1 (an insertional mutation) and Ctnsis2 (a nonsense mutation). Immune histochemistry, renal functions test and HRT2 in vivo confocal microscopy were used to evaluate the age-related renal pathogenesis and treatment efficacy of the scAAV-CTNS virus in corneal pathology. ResultsBoth mutations lead to the production of truncated Ctns proteins. Ctnsis1 and Ctnsis 2 mice exhibit the characteristic of cystinotic corneal crystal phenotype at four-week-old. Treatment with the scAAV-CTNS viral vector decreased the corneal crystals in the treated mice cornea. Ctnsis 1 show renal abnormalities manifested by increased urine volume, reduced urine osmolality, and the loss of response to Desmopressin (dDAVP) at 22-month-old but Ctnsis2 don't manifest renal pathology up to 2 years of age. ConclusionsBoth Ctnsis1 and Ctnsis2 mice exhibit phenotypes resembling human intermediate nephropathic and ocular cystinosis, respectively. scAAV-CTNS viral vectors reduce the corneal cystine crystals and have a great potential as a therapeutic strategy for treating patients suffering from cystinosis.

P-746 Carrier Screening analysis in more than 20.000 patients. Is complete analysis important vs genotyping analysis?

Abstract Study question How comprehensive gene sequencing analysis impacts on carrier screening (CS) results and couple risk reduction? Summary answer Comprehensive genetic sequencing analysis facilitates more accurate carrier rates and provides better information for final panel design and partner risk reduction. What is known already Since CS began in the 1970s, it has helped millions of couples at risk of affected offspring affected by genetic diseases.From the first panels for Ashkenazi Jewish to today’s pan-ethnic CS panels, genetic testing has improved from analysis of a few known pathogenic variants to full sequence analysis. The American College of Medical Genetics and Genomics (ACMG) published Standards and Guidelines for the Interpretation of Sequence Variants in 2015, providing an important tool for full sequence analysis for CS. CS analyses can report only already known mutations (genotyping) or screen for all variants with ACMG-guidelines and laboratory experience (full sequencing). Study design, size, duration This study includes 20774 patients screened with an expanded carrier screening panel of 301 genes, including autosomal recessive (AR) and X-linked (XL) disorders by next-generation sequencing (NGS). ACMG guidelines for variant interpretation were followed in 13954 patients and only pathogenic and likely pathogenic variants were reported. 6820 patients were analyzed with genotyping analysis. 15758 matching analyses were performed for couples and gamete donors. The study has been conducted between August 2018 and December 2022. Participants/materials, setting, methods DNA was extracted from saliva and blood samples and sequenced. The data obtained were processed by means of computer tools. The carrier frequency (CFR) was obtained from the full sequencing analyses. The observed CFRs was compared with the expected CFRs obtained from databases and literature.To define its similarity a range of +-25% was accepted as similar CFR. For matching analyses, high at-risk couples were divided for autosomal recessive diseases(both carriers) and X-linked diseases (female carriers). Main results and the role of chance For the 301 genes analyzed, 34%(103) had a similar CF than the expected one and, more importantly, 65%(198) showed different CFR. In some cases this difference is due to the lack of complete information on the CFR on bibliography and databases like the CFR associated a diseases with more than one gene associated or genes related with more than one disease, some of which with low clinical implications, usually underdiagnosed. One of the genes on which the CFR was not similar to the expected was SMN1. For this well-known gene, related to spinal muscular atrophy, the CFR was higher than expected, probably due to the analysis of the variants c.*3 + 80T>G(p.?),c.*211_*212del(p.?) that indicate a higher risk of 0 + 2 configuration. The patients with these variants and 2 SMN1-exon8 copies are at higher risk to be silent carriers, but they may not be carriers. For the 15758 performed, if one or both patients were analyzed by genotyping analysis, 3,6% (432/12055 matchings) identified had high risk of affected offspring for autosomal or X-Linked recessive diseases. When both patients were analyzed by sequencing, 6% (223/3703 matchings) were identified at high risk of affected offspring of the diseases analyzed allowing a higher identification of couples at risk. Limitations, reasons for caution The analysis was performed on 301 genes, in order to have a better understanding of CFR for panel designs or patients genetic counseling, a larger cohort of genes should be taken into account, these results show the importance of complete analysis to assess the carrier risks. Wider implications of the findings It is important to have wider genetic databases for CFR but also for variant pathogenicity in order to have better results on CFR analyses and panel designs, in order to provide proper genetic counseling to patients looking to improve the chances of healthy offspring. Trial registration number Not applicable

Effects of the COVID-19 Pandemic on SMA Screening and Care: Physician and Community Insights.

As part of efforts to reduce diagnostic delays and enhance clinical trials, Cure SMA evaluated the effects of COVID-19 on SMA care and clinical trial conduct. Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease characterized by progressive, potentially debilitating muscle weakness and atrophy. Uninterrupted access to early diagnosis, disease-modifying treatment, and care for SMA is vital to avoiding irreversible motor neuron death and achieving optimal patient outcomes. Two surveys were conducted: a provider survey and a community survey. The Provider Impact Survey, distributed from November 24, 2020, through March 8, 2021, assessed COVID-19's effects on referrals for evaluation of suspected SMA, cancellations and delays of SMA-related care, and clinical trials. The Community Impact Survey was fielded in three waves between April 7, 2020 and July 19, 2021, in tandem with Cure SMA COVID-19 support programs. A total of 48 completed provider surveys (22 from care sites, 26 from care-and-trial sites) reflected decreases in referrals for suspected SMA, increases in appointment cancellations and delays, and patient reluctance to attend in-person visits due to COVID-19. One-third of care-and-trial sites reported trial recruitment delays, and one-quarter reported pausing trial enrollment. Results of the Community Impact Survey, completed by 2047 individuals, showed similar disruptions, with 55% reporting changes or limitations in accessing essential SMA-related services. This research evaluates the pandemic's interruption of SMA care and research. These insights can help mitigate and increase preparedness for future disruptive events. Expanded use of virtual tools including telehealth and remote monitoring may enhance continuity and access. However, additional research is required to evaluate their effectiveness. While this research was specific to SMA, its findings may have relevance for other patient communities.

Multifaceted Approach for Quantification and Enzymatic Activity of Iduronate-2-Sulfatase to Support Developing Gene Therapy for HunterSyndrome.

Mucopolysaccharidosis type II, commonly called Hunter syndrome, is a rare X-linked recessive disease caused by the deficiency of the lysosomal enzyme iduronate-2-sulphatase (I2S). A deficiency of I2S causes an abnormal glycosaminoglycans accumulation in the body's cells. Although enzyme replacement therapy is the standard therapy, adeno-associated viruses (AAV)-based gene therapy could provide a single-dose solution to achieve a prolonged and constant enzyme level to improve patient's quality of life. Currently, there is no integrated regulatory guidance to describe the bioanalytical assay strategy to support gene therapy products. Herein, we describe the streamlined strategy to validate/qualify the transgene protein and its enzymatic activity assays. The method validation for the I2S quantification in serum and method qualification in tissues was performed to support the mouse GLP toxicological study. Standard curves for I2S quantification ranged from 2.00 to 50.0 μg/mL in serum and 6.25 to 400 ng/mL in the surrogate matrix. Acceptable precision, accuracy, and parallelism in the tissues were demonstrated. To assess the function of the transgene protein, fit-for-purpose method qualification for the I2S enzyme activity in serum was performed. The observed data indicated that the enzymatic activity in serum increased dose-dependently in the lower I2S concentration range. The highest I2S transgene protein was observed in the liver among tissue measured, and its expression level was maintained up to 91 days after the administration of rAAV8 with a codon-optimized human I2S. In conclusion, the multifaceted bioanalytical method for I2S and its enzymatic activity were established to assess gene therapy products in Hunter syndrome.

Purine Nucleoside Phosphorylase Deficient Severe Combined Immunodeficiencies: A Case Report and Systematic Review (1975-2022).

Purine nucleoside phosphorylase deficient severe combined immunodeficiency (PNP SCID) is one of the rare autosomal recessive primary immunodeficiency disease, and the data on epidemiology and outcome are limited. We report the successful management of a child with PNP SCID and present a systematic literature review of published case reports, case series, and cohort studies on PNP SCID listed in PubMed, Web of Science, and Scopus from 1975 until March 2022. Forty-one articles were included from the 2432 articles retrieved and included 100 PNP SCID patients worldwide. Most patients presented with recurrent infections, hypogammaglobulinaemia, autoimmune manifestations, and neurological deficits. There were six reported cases of associated malignancies, mainly lymphomas. Twenty-two patients had undergone allogeneic hematopoietic stem cell transplantation with full donor chimerism seen mainly in those receiving matched sibling donors and/or conditioning chemotherapy before the transplant. This research provides a contemporary, comprehensive overview on clinical manifestations, epidemiology, genotype mutations, and transplant outcome of PNP SCID. These data highlight the importance of screening for PNP SCID in cases presented with recurrent infections, hypogammaglobulinaemia, and neurological deficits.

Whole-exome sequencing identified novel DNAH5 homozygous variants in two consanguineous families with primary ciliary dyskinesia.

Whole-exome sequencing identified novel DNAH5 homozygous variants in two consanguineous families with primary ciliary dyskinesia.

Multiple Polycystic Organs in A Middle Age Female: A Rare Case of More Than Ten Years Without Surgical Intervention

Some organs are recognized to develop cysts more common than others do; these include the kidney the liver, the pancreas and the spleen. The structure and function of these organs may play a role. The frequency of polycystic kidney is variable. It is reported as 50 or less in 100000 (5 in 10000), 1 in 400 and 1 in 1000 life birth. Prevalence of autosomal dominant polycystic kidney disease (ADPKD) is thought to be overestimated by 2 to 5 folds. Multiple polycystic organs are not common, and reviewing the literature revealed some case reports, which indicates that such cases do not have regular pattern. Inherited polycystic kidney disease has two varieties; autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD).

Cystin is required for maintaining fibrocystin (FPC) levels and safeguarding proteome integrity in mouse renal epithelial cells: A mechanistic connection between the kidney defects in cpk mice and human ARPKD.

Autosomal recessive polycystic kidney disease (ARPKD) is caused primarily by mutations in PKHD1, encoding fibrocystin (FPC), but Pkhd1 mutant mice failed to reproduce the human phenotype. In contrast, the renal lesion in congenital polycystic kidney (cpk) mice, with a mutation in Cys1 and cystin protein loss, closely phenocopies ARPKD. Although the nonhomologous mutation diminished the translational relevance of the cpk model, recent identification of patients with CYS1 mutations and ARPKD prompted the investigations described herein. We examined cystin and FPC expression in mouse models (cpk, rescued-cpk (r-cpk), Pkhd1 mutants) and mouse cortical collecting duct (CCD) cell lines (wild type (wt), cpk). We found that cystin deficiency caused FPC loss in both cpk kidneys and CCD cells. FPC levels increased in r-cpk kidneys and siRNA of Cys1 in wt cells reduced FPC. However, FPC deficiency in Pkhd1 mutants did not affect cystin levels. Cystin deficiency and associated FPC loss impacted the architecture of the primary cilium, but not ciliogenesis. No reduction in Pkhd1 mRNA levels in cpk kidneys and CCD cells suggested posttranslational FPC loss. Studies of cellular protein degradation systems suggested selective autophagy as a mechanism. In support of the previously described function of FPC in E3 ubiquitin ligase complexes, we demonstrated reduced polyubiquitination and elevated levels of functional epithelial sodium channel in cpk cells. Therefore, our studies expand the function of cystin in mice to include inhibition of Myc expression via interaction with necdin and maintenance of FPC as functional component of the NEDD4 E3 ligase complexes. Loss of FPC from E3 ligases may alter the cellular proteome, contributing to cystogenesis through multiple, yet to be defined, mechanisms.

A homozygous founder variant in PDE2A causes paroxysmal dyskinesia with intellectual disability.

Intellectual developmental disorder with paroxysmal dyskinesia or seizures (IDDPADS, OMIM#619150) is an ultra-rare childhood-onset autosomal recessive movement disorder manifesting paroxysmal dyskinesia, global developmental delay, impaired cognition, progressive psychomotor deterioration and/or drug-refractory seizures. We investigated three consanguineous Pakistani families with six affected individuals presenting overlapping phenotypes partially consistent with the reported characteristics of IDDPADS. Whole exome sequencing identified a novel missense variant in Phosphodiesterase 2A (PDE2A): NM_002599.4: c.1514T > C p.(Phe505Ser) that segregated with the disease status of individuals in these families. Retrospectively, we performed haplotype analysis that revealed a 3.16 Mb shared haplotype at 11q13.4 among three families suggesting a founder effect in this region. Moreover, we also observed abnormal mitochondrial morphology in patient fibroblasts compared to controls. Belonging to diverse age groups (13 years-60 years), patients presented paroxysmal dyskinesia, developmental delay, cognitive abnormalities, speech impairment, and drug-refractory seizures with variable onset of disease (as early as 3 months of age to 7 years). Together with the previous reports, we observed that intellectual disability, progressive psychomotor deterioration, and drug-refractory seizures are consistent outcomes of the disease. However, permanent choreodystonia showed variability. We also noticed that the later onset of paroxysmal dyskinesia manifests severe attacks in terms of duration. Being the first report from Pakistan, we add to the clinical and mutation spectrum of PDE2A-related recessive disease raising the total number of patients from six to 12 and variants from five to six. Together, with our findings, the role of PDE2A is strengthened in critical physio-neurological processes.

Genotype–phenotype associations in Alström syndrome: a systematic review and meta-analysis

BackgroundAlström syndrome (ALMS; #203800) is an ultrarare monogenic recessive disease. This syndrome is associated with variants in the ALMS1 gene, which encodes a centrosome-associated protein involved in the regulation of...

#4413 MOLECULAR SPECTRUM OF GENETIC ANOMALIES IN PEDIATRIC PATIENTS WITH EARLY ONSET OF RENAL CYSTIC DISEASE

Abstract Background and Aims Renal cystic disease (RCD) includes a spectrum of disorders with heterogenous clinical presentation. Among RCD are autosomal dominant polycystic kidney disease (ADPKD), autosomal recessive polycystic kidney disease (ARPKD), ciliopathies, HNF1B-nephropathy, and congenital anomalies of the kidneys and of the urinary tract (CAKUT). Diagnosis is based on clinical criteria, yet, given the extreme genetic heterogeneity and phenotypic overlap among different conditions, confirmation by genetic testing is paramount for correct clinical management and recurrence risk assessment. Although genotype-phenotype correlations are scanty, recently, coexisting variants in the same gene or in multiple cystogenes have been associated with earlier and more severe renal phenotype. The aim of this study is to describe the clinical and molecular characteristics of pediatric patients with early onset of RCD and provide genotype-phenotype correlations. Method A retrospective study was conducted collecting patients with a prenatal or early-childhood ultrasound finding of renal hyper-echogenicity or cysts. All patients were followed at the Pediatric Nephrology Unit of the Città della Salute e della Scienza University Hospital of Torino, Italy. Genetic analyses were mostly performed at the Immunogenetic and Transplant Biology Unit and included clinical exome sequencing (CES), array-CGH, MLPA and single gene testing. Results 65 patients we recruited, 42 males (64.6%) and 23 females (35.4%), mean age 8 ± 5.9 years (range 0-18). The most frequent clinical suspicion was ADPKD (n = 40, 61.5%), followed by CAKUT (n = 9, 13.8%), ARPKD (n = 8, 12.3%), ciliopathy and tuberous sclerosis complex (TSC) (n = 3, 4.6% for each condition), and medullary cystic disease (n = 2, 3.1%). Overall, causative variants (C4/C5) were identified in 39 patients (60.0%), 18 (27.7%) were carriers of variants of uncertain significance (C3) and 8 (12.3%) were inconclusive. Among the 40 patients with a clinical suspicion of ADPKD, 23 received a conclusive genetic diagnosis with 20 (87%) variants in PKD1, 2 (8.7%) in PKD2, one in HNF1B and 14 carried C3 variants. All patients with a clinical suspicion of ARPKD received molecular confirmation and, notably, in one case we observed biallelic variants in PKD1. Among the 21 patients with PKD1 variants, 6 (28.6%) had multiple PKD1 variants and 2 (9.5%) carried an additional PKHD1 variant. TSC diagnosis was confirmed in all 3 cases and two of them (66.7%) carried a contiguous gene TSC2-PKD1 deletion. Two out of 3 (66.7%) patients with a clinical suspicion of ciliopathy carried biallelic variants in BBS10, in one case associated with an additional variant in PKD2. Four (44.4%) CAKUT cases were solved with 3 causative variants in HNF1B (75%) and one in PAX2 (25%), 2 cases (22.2%) carried C3 variants and 3 (33.3%) were inconclusive. Causative variants were de novo in 10 cases (25.6%). Conclusion Our data confirms that genetic evaluation is a powerful tool for the diagnosis of RCD, as witnessed by a detection rate of 60%. Although the clinical suspicion was confirmed in the majority of cases, one suspected ARPKD case carried two PKD1 variants and one suspected ADPKD case carried a whole HNF1B gene deletion, highlighting the need for extensive genetic analysis. Moreover, nine patients had multiple variants potentially contributing with additive effect to a more severe renal phenotype: 6 patients had two variants in PKD1, 2 patients with a PKD1 variant had an additional variant in PKHD1 and one patient had biallelic BBS10 variants plus a nonsense PKD2 variant. In this context, genetic analysis by CES permits simultaneous evaluation of all RCD associated genes, uncovering both multiple variants and clinical phenocopies. In conclusion, the CES driven genetic characterization of pediatric patients with renal cysts allows to avoid misdiagnosis, minimize diagnostic invasive investigations, set up correct follow-up, and define recurrence risk, with a time- and cost- efficient approach.