Monogenic Disorders Research Articles

Opportunistic genomic screening has clinical utility: An interventional cohort study

Practice is shifting toward genome-first approaches, such as opportunistic screening for secondary findings (SFs). Analysis of SFs could be extended beyond medically actionable results to include non-medically actionable monogenic disease risks, carrier status, pharmacogenomic variants, and risk variants for common complex disease. However, evidence on the clinical utility of returning these results is lacking. We assessed the outcomes of opportunistic screening for a broad spectrum of SFs by evaluating the yield, impact on clinical management, and consistency between SFs and participants' clinical features and family history. Adult cancer patients had GS with the option to learn multiple categories of SFs. Outcomes data were collected through chart review and participant-reported measures up to one year after return of results. All participants (n=139, 85.6% female, average 54.6 years old) who elected to learn SFs had ≥1 variant reported (100% [139/139]). The yield of reportable findings was highest for pharmacogenomic variants (97.8% [135/138] of participants), followed by common disease risk variants (89.4% [118/132]), carrier status (89.3% [117/131]), and variants related to Mendelian (27.2% [34/125]), medically actionable (15.2% [21/138]), and early-onset neurodegenerative (2.6% [3/117]) disease risks. SFs from the ACMG list (v3.2, non-cancer genes) were reported in 1.4% (2/138) of participants. SFs across all categories demonstrated clinical utility by prompting management changes in 28.1% (39/139) of participants. Moreover, a considerable proportion of participants had suggestive clinical features (49.0% (24/49)]) or family history (21.8% (27/124)) potentially related to their SFs. Our findings indicate there are potential benefits from opportunistic screening for a broad range of SFs.

Concordance Between Biochemical and Molecular Diagnosis Obtained by WES in Mexican Patients with Inborn Errors of Intermediary Metabolism: Utility for Therapeutic Management.

Biochemical phenotyping has been the milestone for diagnosing and managing patients affected by inborn errors of intermediary metabolism (IEiM); however, identifying the genotype responsible for these monogenic disorders greatly contributes to achieving these goals. Herein, whole-exome sequencing (WES) was used to determine the genotypes of 95 unrelated Mexican pediatric patients suspected of having IEiM. They were classified into those bearing specific biochemical abnormalities (Group 1), and those presenting unspecific biochemical profiles (Group 2). The overall concordance between the initial biochemical diagnosis and final genotypic diagnoses was 72.6% (N = 69/95 patients), with the highest concordance achieved in Group 1 (91.3%, N = 63/69), whereas the concordance was limited in Group 2 (23.07%). This finding suggests that previous biochemical phenotyping correlated with the high WES diagnostic success. Concordance was high for urea cycle disorders (94.1%) and organic acid disorders (77.4%). The identified mutational spectrum comprised 83 IEiM-relevant variants (pathogenic, likely pathogenic, and variants of uncertain significance or VUS), including three novel ones, distributed among 29 different genes responsible for amino acid, organic acid, urea cycle, carbohydrate, and lipid disorders. Inconclusive WES results (7.3%, N = 7/95) relied on monoallelic pathogenic genotypes or those involving two VUS for autosomal-recessive IEiMs. A second monogenic disease was observed in 10.5% (N = 10/95) of the patients. According to the WES results, modifications in treatment had to be made in 33.6% (N = 32/95) of patients, mainly attributed to the presence of a second monogenic disease, or to an actionable trait. This study includes the largest cohort of Mexican patients to date with biochemically suspected IEiM who were genetically diagnosed through WES, underscoring its importance in medical management.

CRISPR-Cas9: Revolutionizing Gene Therapy for Genetic Disorders

Faulty or mutated genes cause multiple human disorders such as cancer, neurogenerative disorders, and cardiovascular diseases. These mutations in genes are usually inherited. Many treatments have been established to cure such diseases, but gene therapy is the most promising strategy. It’s an application of biotechnology that is based on correcting and replacing the mutated gene with the healthy gene, providing the genes for the proper expression of desired proteins required for curing the disease. In clinical settings, gene therapy has proved itself as a very promising treatment but has some drawbacks. Traditionally, these methods involved viral vectors that are used to deliver correct genes and replace them with the mutated genes, in patients. These approaches have somehow potential to cure diseases but often off-target effects, limitations in the editing process, and immune responses caused by patients’ immune systems are the main challenges that are the main shortcomings of this method. However, the discovery of the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated nuclease protein 9 (Cas9) genome editing system (CRISPR/Cas9) in 2012 and its development have increased the value of gene therapy in the therapeutic world [1]. CRISPR/Cas9 is a revolutionizing tool that has been in gene therapy for knocking in and out gene to correct the mutation associated with many genetic diseases. This system has evolved greatly and has many isomers using different strategies to improve both applied, basic research and its clinical application. The ability of CRISPR-Cas9 to target various genetic diseases is one of its greatest advantages. Mutation in single gene results in monogenic diseases such as cystic fibrosis, muscular dystrophy, and sickle cell anemia, and this system has shown the potential to edit or fix the defective genes, causing these diseases. Even in the case of complex disorders caused by the mutation in multiple genes such as several types of cancer, and cardiovascular diseases, CRISPR has shown very positive results. The application of CRISPR-Cas9 in gene therapy is very promising and has tremendous potential to give cures for many complex disorders. The ethical issue regarding the editing of human DNA and the inheritance of modified DNA into the next generation is still under discussion and causing hurdles in uncovering the full potential of this system. Researchers are working to increase its efficiency and specificity to reduce the off-target sequences so that only targeted modification can be achieved. Moreover, they are trying to give possible results to reduce ethical concerns. CRISPR has evolved greatly and has many isomers using different strategies to improve both applied, basic research and its clinical application in the future.

Reproductive outcomes after preimplantation genetic testing in couples with sex chromosome abnormalities: a retrospective cohort study of 83 couples.

To explore the effects of parental sex chromosome abnormality on their preimplantation embryos. This is a retrospective cohort study including 83 couples with sex chromosome abnormalities undergoing preimplantation genetic testing (PGT) between 2013 to 2023. The preimplantation genetic testing results and pregnancy outcomes were compared to those of a control group consisting of 166 age-matched couples with normal karyotypes who underwent preimplantation genetic testing for monogenic disorders (PGT-M). Student's t-tests, chi-square or Fisher's exact tests were applied to compare clinical characteristics. The embryo euploidy rate was lower (58.94% vs 65.44%, P = 0.048, OR 0.76, 95%CI [0.58,0.99]) and the sex chromosomal aneuploidy rate was higher in the couples with sex chromosome abnormalities than control group (6.62% vs 2.63%, P = 0.004, OR 2.63, 95%CI [1.37,5.05]). The pregnancy outcomes including clinical pregnancy rates (48.57% vs 57.25%, P = 0.305) and live birth rates (47.14% vs 52.90%, P = 0.465) were similar between the two groups in their first embryo transfer cycles. To avoid high risk of embryo aneuploidy and sex chromosome abnormalities, preimplantation genetic testing should be recommended to couples with sex chromosome abnormalities.

Neuroimaging to Genotype: Delineating the Spectrum of Disorders With Deficient Myelination in the Indian Population.

Several genetic disorders are associated with either a permanent deficit or a delay in central nervous system myelination. We investigated 24 unrelated families (25 individuals) with deficient myelination after clinical and radiological evaluation. A combinatorial approach of targeting and/or genomic testing was employed. Molecular diagnosis was achieved in 22 out of 24 families (92%). Four families (4/9, 44%) were diagnosed with targeted testing and 18 families (18/23, 78%) were diagnosed using broad genomic testing. Overall, 14 monogenic disorders were identified. Twenty disease-causing variants were identified in 14 genes including PLP1, GJC2, POLR1C, TUBB4A, UFM1, NKX6-2, DEGS1, RNASEH2C, HEXA, ATP7A, SETBP1, GRIN2B, OCLN, and ZBTB18. Among these, nine (45%) variants are novel. Fourteen families (82%, 14/17) were diagnosed using proband-only exome sequencing (ES) complemented with deep phenotyping, thus highlighting the utility of singleton ES as a valuable diagnostic tool for identifying these disorders in resource-limited settings.

Lipoprotein(a) and cardiovascular prognosis of familial dyslipidemias: data from a 10-year follow-up study

Abstract Background Familial dyslipidemias, such as heterozygous familial hypercholesterolemia (FH) and familial combined hyperlipidemia (FCH) are associated with premature cardiovascular (CV) disease. On the other hand, increased lipoprotein(a) [Lp(a)] is considered as the most prevalent monogenic lipid disorder in the general population. Purpose This study aimed to longitudinally follow up two specific populations with familial dyslipidemias associated with increased CV risk, namely FH and FCH, and compare them with reference to their CV prognosis, investigating in parallel the effect of Lp(a) levels. Methods 433 patients with FH (34% males, mean age 44.2±12.8 years) and 476 patients with FCH (57% males, mean age 49.0±11.1 years) from the outpatient lipid clinic of our hospital, without history of CV disease, who fulfilled the FH and FCH criteria, respectively, participated in the study. Participants were evaluated for a mean follow-up period of 9.6±7.6 years, with at least one annual visit. Venous blood samples were obtained at baseline in all patients for the determination of lipid profile and levels of Lp(a). All subjects were on lipid-lowering medication during the follow-up period. The endpoint of our study was the composite of major CV events (coronary artery disease events and stroke). Results The incidence of the composite endpoint of major CV events during the follow-up period in the total population was 6.5%, while it was greater in patients with FH compared to patients with FCH (8.1% vs 5.5%, p=0.03). Regarding CV risk factors, FCH compared to FH patients had greater prevalence of baseline hypertension (36% vs 9.7%, p<0.001) and diabetes (11% vs 2%, p<0.001), whereas FH patients had greater Lp(a) levels (37.4±40.3 vs 29.7±34.6 mg/dl, p<0.01). Multiple Cox regression analysis revealed that FH patients had greater CV risk compared to FCH patients (HR 2.17, 95% CI 1.10-4.26, p=0.02). Moreover, in FH patients, increased baseline Lp(a) levels (≥30mg/dl) were an independent predictor of major adverse CV events (HR 2.37 95% CI 1.41-4.90, p=0.02), whereas in FCH patients increased Lp(a) was not an independent predictor. In FCH patients the presence of diabetes at baseline was a strong independent prognosticator of adverse CV events (HR 3.56 95% CI 1.19-11.33, p=0.03), after adjustment for confounding factors. Conclusions FH patients have greater CV risk compared to FCH patients. In FH patients, the presence of increased Lp(a) doubles the CV risk, beyond low density lipoprotein cholesterol levels. On the other hand, in FCH patients the presence of diabetes triples the CV risk, whereas Lp(a) does not convey an independent prognostic value.

Management of children with heterozygous familial hypercholesterolemia worldwide: a meta-analysis

Abstract Background HeFH is one of the most frequent monogenic disorders in the world, leading to premature ASCVD. Purpose The aim of this meta-analysis was to evaluate the efficacy and safety of lipid lowering therapy (LLT) and achievement of LDL-C goal in heFH children. Methods The main endpoint was efficacy of goal achievement for LDL-C and other lipid parameters: total cholesterol [TC], triglycerides [TG], high density lipoprotein cholesterol [HDL-C], apolipoprotein B [apo B] and lipoprotein(a) [Lp(a)]), and the LLT safety (adverse events [AEs], including endocrine function, and growth indices). The secondary endpoint was an effect of LLT on attainment of LDL-C goal treatment (<3.5 mmol/L/130 mg/dL). Results A total of 41 studies with 4667 pediatric patients at mean age 12.08±2.4 years were included. At median follow-up of 18.8 months, the group on LLT had significantly higher mean reductions of TC, LDL-C, TG, and increased HDL-C compared to control (-1.75 [-67,7 mg/dl], -1.84 [-71.2 mg/dl], -0.11 [-9.74 mg/dl], 0.08 mmol/L [3.1 mg/dl], respectively, p<0.001 for all). In the subgroup analysis according to different types of LLT we observed a significantly higher mean reduction of LDL-C by statin combined with ezetimibe treatment, followed by PCSK9 inhibitors, statins in monotherapy, and monotherapy with ezetimibe (-2.48 [-95.9 mg/dl], -2.16 [-83.5 mg/dl], -2.03 [-78.5 mg/dl], and -1.50 mmol/L [-58 mg/dl], respectively, test for overall effect: p<0.001). The pooled LDL-C was reduced by 33.44% (-2.14 mmol/L [-82.8 mg/dl], p<0.001) and failed to reach the goal treatment (<3.5 mmol/L) by 12.6% (95%CI, 12.4 – 12.9%). 38.7% of children achieved the LDL-C goal, 23.9% fell short by up to 10%, 10.7% experienced moderate failure (were over the LDL-C target between >10-20%), and 26.7% failed by more than 20% to reach the LDL-C target. When comparing different regions, only Sweden and Greece achieved the LDL-C goal <3.5 mmol/L in the follow-up, followed by the Netherlands, Norway, Poland, USA, UK, France, Spain, Belgium, and Austria (with the following additional required LDL-C reduction to be on the goal: 2.2%, 3.4%, 3.5%, 8.9%, 10.2%, 11.2%, 11.2%, 15%, 19.4%, respectively). For other investigated countries over 20% mean LDL-C reduction was required. All parameters related to endocrine function and demographic indices were unaffected by LLT therapy (p>0.05). The adverse events were not reported significantly higher when compared to the control and the prevalence of therapy discontinuation was only 0.8%. Conclusions Despite the efficacy of LLT in children with HeFH and the low occurrence of discontinuation-related adverse events, achieving LDL-C treatment goals was relatively rare, with large differences between the investigated countries. These results underscore the importance of considering early combination therapy of statins and ezetimibe, and PCSK9 inhibitors (if available) to attain LDL-C goals effectively.Lipoproteins reduction with LLT.Goal achievement and therapy safety.

Advancing Precision Nutrition in Endometriosis Care: The Role of Nutrigenomics and Nutrigenetics

Endometriosis is a gynecological disorder that affects 10-15% of women of reproductive age. It is characterized as a chronic, inflammatory, and hormone-dependent disease in which the endometrial tissue is present on the external uterine lining, resulting in infertility and pelvic pain. Some research studies stated that about 97% of human diseases are monogenic diseases associated with genes. Thus, modifying dietary intake (personalized diet) can potentially prevent monogenic diseases. Nutrigenomics and nutrigenetics have garnered substantial interest among researchers as potential avenues for managing chronic conditions like diabetes, cancer, obesity, and cardiovascular disorders. Nutrigenomics ascertains the effects of food and ingested nutrients on gene expression and regulation, tailoring nutritional needs to an individual’s genetic makeup, thereby facilitating personalized diets. On the other hand, nutrigenetics investigates how an individual’s genetic composition influences their response to dietary elements. Both fields could be beneficial in modifying various disease conditions. Furthermore, it explores the effects of precision nutrition, direct-to-consumer genetic testing, and the role of artificial intelligence in the nutrigenetics and nutrigenomics approach to managing endometriosis. This review aims to provide a comprehensive overview of potential treatment modalities for endometriosis through the lenses of nutrigenomics and nutrigenetics. It highlights the interplay between dietary interventions and gene expression, elucidating how personalized approaches could potentially modify the course of endometriosis.

Uncovering ASO-Targetable Deep Intronic AIRE Variants: Insights and Therapeutic Implications.

High-throughput DNA sequencing has accelerated the discovery of disease-causing genetic variants, yet only in 10-40% of cases yield a genetic diagnosis. Increased implementation of genome sequencing has enabled a deeper exploration of the noncoding genome and recognition of noncoding variants as major contributors to disease. In a recent study, we identified a deep intronic variant in the AutoImmune REgulator (AIRE) gene (c.1504-818 G>A) as the cause of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), a life-threatening monogenic autoimmune disorder most often caused by biallelic AIRE defects. This deep intronic variant disrupts normal splicing AIRE , causing pseudoexon inclusion and altered protein function. By developing an antisense oligonucleotide (ASO) targeting the pseudoexon sequence, we restored normal AIRE transcript in vitro, thereby revealing a potential genotype-specific candidate treatment. Our study illustrates key aspects of intronic variant detection, validation, and candidate ASO development. Herein, we briefly highlight the growing potential of ASO-based therapies for deep intronic variants, addressing the unmet need of personalized, genotype-specific therapies in diseases lacking curative options.

Estimation of carrier frequencies of autosomal and X-linked recessive genetic conditions based on gnomAD v4.0 data in different ancestries.

Monogenic rare diseases contribute significantly to infant deaths and pediatric hospitalizations and cause burden to the patients and their families. The American College of Medical Genetics and Genomics recommended in 2021 that carrier screening of autosomal recessive and X-linked conditions with a carrier frequency of ≥ 1/200 and a severe or moderate phenotype should be offered when planning or during pregnancy. In November 2023 gnomAD v4.0 was released. It contains in total 807,162 individuals, being nearly 5x larger than previous versions, that have been used to estimate gene carrier frequencies (GCF). We utilized gnomAD v4.0 (GRCh38) to calculate the GCFs for available genetic ancestry groups for variants having pathogenic or likely pathogenic classification (>80% of submissions) in ClinVar. We calculated GCF separately for exomes and genomes, and combined data, and at-risk couple frequencies (ACF) per genetic ancestry group RESULTS: In total, 324 genes had a GCF ≥ 1/200 in at least one ancestry subgroup. The number of genes with GCF ≥ 1/200 varied greatly between subgroups. ACFs were more similar, Ashkenazi Jewish having the highest ACF of 6.11%. Improved understanding of carrier risks and updated carrier screening content would allow patients to make more informed reproductive decisions.

Accurate prenatal diagnosis of facioscapulohumeral muscular dystrophy 1 using nanopore sequencing

BackgroundFacioscapulohumeral muscular dystrophy 1 (FSHD1) is an autosomal dominant muscular disorder mainly caused by the contraction and hypomethylation of the D4Z4 repeat array in chromosome 4q35. Prenatal diagnosis of FSHD1...

Study protocol for LOMCAD Trial: Effect of lomerizine hydrochloride to prevent recurrence of cerebral ischemic events in CADASIL patients

ObjectivesCerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is one of the most common monogenic cerebral small vessel diseases. Our previous observational study suggested that lomerizine hydrochloride, a calcium channel blocker approved in Japan in 1999 for the prevention of migraine headaches, is also effective for preventing recurrent ischemic stroke in CADASIL patients. The aim of this study (LOMCAD trial) is to verify the efficacy of lomerizine hydrochloride. Materials and MethodsThis is a multicenter, prospective, single-arm trial, using a historical control for comparison. CADASIL patients with a history of two or more cerebral ischemic events within the last two years will be administered lomerizine hydrochloride (5-mg tablet twice daily) for 24 months. The primary endpoint is symptomatic cerebral ischemic events during the 24-month period. Using our historical data and Bayesian sample size calculation based on a prior predictive distribution, the planned sample size was determined as 20 subjects. ConclusionWe have planned a clinical trial to verify the effectiveness of lomerizine hydrochloride as prophylaxis to prevent recurrent cerebral ischemic events in CADASIL patients. RegistrationThe LOMCAD trial has been registered in the Japan Registry of Clinical Trials (jRCTs051220072, https://jrct.niph.go.jp/latest-detail/jRCTs051220072).

Clinical utility of expanded carrier screening in the preconception and prenatal population: A Chinese cohort study

ObjectivesTo evaluate the clinical utility of expanded carrier screening (ECS) in Chinese preconception and prenatal populations, focusing on carrier frequency and the impact on at-risk couples (ARCs). MethodsData from 6,298 Chinese individuals from 4,420 families who underwent a 149-gene ECS panel at a single center were analyzed. The prevalence of positive carriers and ARCs was determined, with follow-up on reproductive decisions and pregnancy outcomes for ARCs. ResultsOf the individuals screened, 2,673 (42.4 %) were carriers of at least one pathogenic or likely pathogenic variant, and 98 (2.22 %) ARCs were identified. GJB2-related deafness and Duchenne muscular dystrophy were the most common autosomal recessive (AR) and X-linked disorders. Screening the top 11 (gene carrier rate [GCR] ≥ 1/100), 22 (GCR ≥ 1/200), and 41 (GCR ≥ 1/331) AR genes could identify 53.5 %, 67.9 %, and 81.3 % of variants, respectively. The corresponding ratios for identified ARCs were 90.4 %, 94.0 %, and 100 %. Follow-up data from 80 ARCs indicated that 75.0 % (60/80) took significant action based on the ECS results. Additionally, four families (3.5 %, 4/115) were identified at risk for a second disease unrelated to their initial family monogenic history. ConclusionsThis study, representing the largest cohort of a moderate-sized ECS panel test in the Chinese population, demonstrates the clinical utility of ECS in both healthy individuals and those with a family history of monogenic disorders. The data obtained provide valuable insights for developing a Chinese-specific ECS panel. Tailored approaches are critical for wider adoption and successful routine application of ECS.

Clinical and Genetic characteristics of patients with Peripheral Retinal Fleck in Koreans.

To describe the clinical and genetic features of Korean patients with peripheral retinal flecks unrelated to aging. A retrospective analysis was conducted on the clinical characteristics of patients with symmetric peripheral retinal flecks. Age-related deposits such as reticular pseudodrusen were excluded, as well as secondary deposits related to intraocular inflammation, tumor, and drug toxicity. Multimodal imaging, electrophysiological examinations, and genetic testing were analyzed. A total of 10 patients (2 males and 8 females) with bilateral peripheral flecks were enrolled in this study. A mean age at diagnosis was 30.5±19.6 years (4-59 years). Within the 10 patients, 6 were genetically confirmed with monogenic retinal disorders. Biallelic pathogenic variants in RDH5 were found in 5 patients, and 1 patient was diagnosed with retinopathy related to Alport syndrome due to a pathogenic variant in COL4A5. Although not genetically confirmed, one case associated with nanophthalmos and another case showing chorioretinal mottling in a carrier of ocular albinism have been identified. In one patient, genetic testing also revealed unknown causes. The mean logMAR initial visual acuity was 0.12±0.18 and 0.07±0.18 in right and left eyes, respectively. Night blindness was reported by 4 patients (40%), with 3 showing decreased or delayed rod response in electroretinogram, particularly those with RDH5 mutations. Differences in the deposit layers and the patterns of flecks were observed on multimodal imaging. In the study population, we observed various causes and clinical differences in the retinal fleck patterns among Koreans, including RDH5-related fundus albipunctatus and Alport syndrome. Despite reports of night blindness symptoms in some cases, all patients demonstrated satisfactory corrected visual acuity.

Genetics in nephrology - any news?

While genetic kidney diseases were long regarded as a rare cause of kidney failure, it has been shown in recent years that they account for a relevant proportion of cases. In cohorts of kidney transplant recipients, a monogenic cause is found in up to 30% of cases. Identifying the genetic cause of kidney disease has become much easier thanks to technological advances in DNA sequencing. The focus has now shifted to understanding the significance of the findings and identifying diagnostic gaps. It is still not possible to clarify all CKD cases of unclear aetiology. Besides very effective generic treatments for monogenic kidney disease (e.g., ACE-inhibitor use in Alport Syndrome), increasing knowledge of the pathophysiology of genetic kidney diseases has led to a growing number of targeted therapies. These include the treatment of ADPKD with Tolvaptan, which has now been in use for 10 years. Recently, exciting, and completely new approaches have been added, such as the first siRNA therapies in nephrology for primary hyperoxaluria type 1, the targeted treatment of hyperphagia in Bardet-Biedl syndrome, the therapy of APOL1-associated kidney disease or the use of the HIF-2 antagonist Belzutifan for renal cell carcinoma associated with Von-Hippel-Lindau syndrome. The new possibilities in the treatment of patients with genetic kidney diseases have also clearly revealed deficits in current patient care. Centers of excellence with extensive experience in this area therefore play an important role in improving care. This also applies to the further training of colleagues in the field. In Germany, the National Action Alliance for People with Rare Diseases (NAMSE) and the nationwide establishment of - to date - 36 centers for rare diseases play an important role in this regard.

Global cellular proteo-lipidomic profiling of diverse lysosomal storage disease mutants using nMOST.

Lysosomal storage diseases (LSDs) comprise ~50 monogenic disorders marked by the buildup of cellular material in lysosomes, yet systematic global molecular phenotyping of proteins and lipids is lacking. We present a nanoflow-based multi-omic single-shot technology (nMOST) workflow that quantifies HeLa cell proteomes and lipidomes from over two dozen LSD mutants. Global cross-correlation analysis between lipids and proteins identified autophagy defects, notably the accumulation of ferritinophagy substrates and receptors, especially in NPC1-/- and NPC2-/- mutants, where lysosomes accumulate cholesterol. Autophagic and endocytic cargo delivery failures correlated with elevated lyso-phosphatidylcholine species and multi-lamellar structures visualized by cryo-electron tomography. Loss of mitochondrial cristae, MICOS-complex components, and OXPHOS components rich in iron-sulfur cluster proteins in NPC2-/- cells was largely alleviated when iron was provided through the transferrin system. This study reveals how lysosomal dysfunction affects mitochondrial homeostasis and underscores nMOST as a valuable discovery tool for identifying molecular phenotypes across LSDs.

An update on autophagy disorders.

Macroautophagy is a highly conserved cellular pathway for the degradation and recycling of defective cargo including proteins, organelles, and macromolecular complexes. As autophagy is particularly relevant for cellular homeostasis in post-mitotic tissues, congenital disorders of autophagy, due to monogenic defects in key autophagy genes, share a common "clinical signature" including neurodevelopmental, neurodegenerative, and neuromuscular features, as well as variable abnormalities of the eyes, skin, heart, bones, immune cells, and other organ systems, depending on the expression pattern and the specific function of the defective proteins. Since the clinical and genetic resolution of EPG5-related Vici syndrome, the paradigmatic congenital disorder of autophagy, the widespread use of massively parallel sequencing has resulted in the identification of a growing number of autophagy-associated disease genes, encoding members of the core autophagy machinery as well as related proteins. Recently identified monogenic disorders linking selective autophagy, vesicular trafficking, and other pathways have further expanded the molecular and phenotypical spectrum of congenital disorders of autophagy as a clinical disease spectrum. Moreover, significant advances in basic research have enhanced the understanding of the underlying pathophysiology as a basis for therapy development. Here, we review (i) autophagy in the context of other intracellular trafficking pathways; (ii) the main congenital disorders of autophagy and their typical clinico-pathological signatures; and (iii) the recommended primary health surveillance in monogenic disorders of autophagy based on available evidence. We further discuss recently identified molecular mechanisms that inform the current understanding of autophagy in health and disease, as well as perspectives on future therapeutic approaches.

Recurrent calcium oxalate calculi: the culprit in disguise.

Congenital sucrase isomaltase deficiency (CSID) is a rare autosomal recessive monogenic disorder of small intestinal malabsorption and manifests typically in early childhood with chronic osmotic diarrhoea. Though there have been case reports in adults presenting with hypercalcemia and renal calculi in CSID, this is quite rare in children. We hereby report a 6-year-old boy who presented with recurrent episodes of calcium oxalate calculi without any gastrointestinal symptoms and was confirmed as having sucrase isomaltase deficiency by genetic analysis.

Preimplantation genetic testing for Cockayne syndrome with a novel ERCC6 variant in a Chinese family.

Cockayne syndrome (CS) is a rare, multisystem, autosomal recessive disorder characterized by cachectic dwarfism, nervous system abnormalities, and premature aging. Mutations in the ERCC6 and ERCC8 genes are the predominant causes of Cockayne syndrome, with ERCC6 gene mutations present in approximately 75% of cases. Trio-based whole-exome sequencing (trio-WES) was employed to identify potential pathogenic variants associated with CS. Preimplantation genetic testing for monogenic disorders (PGT-M) was conducted to prevent the transmission of the pathogenic variant. Two compound heterozygous mutations were identified in ERCC6-c.1297G>T (p. Glu433*) and c.1607T>G (p. Leu536Trp)-with c.1297G>T representing a novel mutation. Four blastocysts resulting from intracytoplasmic sperm injection were subjected to biopsy. Genetic analyses revealed that E1 harbored maternal mutations in diploid embryos, E2 and E3 carried both paternal and maternal mutations in non-diploid embryos, and E4 did not carry paternal or maternal mutations in diploid embryos. Following the transfer of the E4 embryos, a single successful pregnancy was achieved. The successful application of PGT-M in this family offers a potential approach for addressing other monogenic diseases. The findings of this study broaden the variant spectrum of ERCC6 and will contribute to the molecular diagnosis and genetic counseling of CS. This case highlights the feasibility and effectiveness of PGT-M in preventing CS and provides valuable insights for similarly affected families.

Dysregulation of epigenetic modifications in inborn errors of immunity.

Inborn errors of immunity (IEIs) are a group of typically monogenic disorders characterized by dysfunction in the immune system. Individuals with these disorders experience increased susceptibility to infections, autoimmunity and malignancies due to abnormal immune responses. Epigenetic modifications, including DNA methylation, histone modifications and chromatin remodeling, have been well explored in the regulation of immune cell development and effector function. Aberrant epigenetic modifications can disrupt gene expression profiles crucial for immune responses, resulting in impaired immune cell differentiation and function. Dysregulation of these processes caused by mutations in genes involving in epigenetic modifications has been associated with various IEIs. In this review article, we focus on IEIs that are caused by mutations in 13 genes involved in the regulation of DNA methylation, histone modification and chromatin remodeling.