Journal of Medical Genetics最新文献

Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are imprinting disorders caused by genetic or epigenetic aberrations of 15q11.2-q13. Their clinical testing is often multitiered; diagnostic testing begins with methylation-specific multiplex ligation-dependent probe amplification or methylation-sensitive PCR and then proceeds to molecular subtyping to determine the mechanism and recurrence risk. Currently, correct classification of a proband's PWS/AS subtype often requires parental samples, a costly process for families and health systems. The use of nanopore sequencing for molecular diagnosis of PWS and AS has been explored by Yamada et al; however, to confirm heterodisomy parental data were still required. Here, we investigate genome-wide nanopore sequencing in a larger cohort of PWS (18) and AS (6) as a singular test to detect the molecular subtype, without parental data. We accurately subtyped these cases including uniparental heterodisomy, mixed iso-/heterodisomy, type 1 and 2 deletions, microdeletion and UBE3A indels. One PWS case with a previously unresolved diagnosis subtyped as maternal isodisomy. This work highlights the application of long-read sequencing and other imprinted regions outside of the PWS/AS critical region to resolve the molecular diagnosis and subtyping of PWS and AS without parental data. The work also outlines an approach to generically detect heterodisomy through the interrogation of distant imprinted regions.

Background: To delineate the clinical and mutational signatures of patients with CRB1-associated retinopathies.

Methods: This multicentre retrospective cohort study involved 40 patients with CRB1 mutations and 40 age-matched and gender-matched inherited retinal diseases (IRDs). The detailed phenotyping and genotyping characteristics and genotype‒phenotype correlations of the patients were analysed.

Results: The mean age of CRB1 cohort was 27.33±14.63 years. Results showed that yellowish geographic macular degeneration (66.67%), small white or yellow dots (65.6%), hyperopia (62.5%), abnormally laminated retina (61.61%), epiretinal membrane (60.6%) and nummular pigment deposits (50%) were the most common signatures in patients with CRB1 mutations. These clinical signatures were notably more prevalent among CRB1 patients than among individuals in other IRD groups (p<0.001). Early-onset severe retinal dystrophy/Leber congenital amaurosis (EOSRD/LCA) patients are more likely to present these signatures than retinitis pigmentosa (RP) and macular dystrophy (MD) patients. Furthermore, a significant reduction in central foveal thickness coupled with pronounced thickening of the peripheral retina was observed more distinctly in patients with EOSRD/LCA (p<0.001). The choroidal thickness was not significantly altered compared to the normal controls, but was markedly reduced in the other IRD groups (p<0.001). 55 pathogenic variants were identified, 20 of which were novel. Null mutations were associated with EOSRD/LCA patients, and missense mutations were more prevalent in MD and RP patients.

Conclusions: Key clinical and mutational signatures were demonstrated in this study, providing a comprehensive update on CRB1-associated retinopathies that will aid in diagnosis and lay the foundation for future therapeutic studies.

tsRNA is a class of non-coding RNAs derived from mature or precursor tRNAs. In recent years, more and more studies have explored the correlation between tsRNAs and tumours. tsRNAs can affect the biological behaviours of tumour cells such as proliferation, apoptosis and metastasis by regulating gene expression, protein translation or post-transcriptional regulation. In this paper, we systematically review the production, biological function and research progress of tsRNA in tumour and discuss its prospects as biomarkers and therapeutic targets.

Background: Clinical trials for rare disorders have unique challenges due to low prevalence, patient phenotype variability and high expectations. These challenges are highlighted by our study on clonazepam in ARID1B patients, a common cause of intellectual disability. Previous studies on Arid1b-haploinsufficient mice showed positive effects of clonazepam on various cognitive aspects.

Methods: This study used a randomised, double-blinded, placebo-controlled, two-way crossover study (RCT), followed by an N-of-1 design. In the crossover study, ARID1B patients received clonazepam (max 0.5 mg, two times per day) or a placebo for 22 days with a 3-week washout period. Assessments included safety, tolerability, pharmacokinetics, pharmacodynamics on neurocognitive tasks, behaviour and cognitive function. During phase I of the N-of-1 trial the optimal dosage and individual treatment goals were determined. Phase II evaluated the treatment effect. This phase was composed of three periods: an open-label period with placebo (4 weeks), followed by a double-blinded period (6 weeks), followed by an open-label period in which the patient received clonazepam (4 weeks).

Results: In the clonazepam group (n=16, 15 completing both periods), seven (44%) reported improvement on Clinician Global Impression of Improvement versus two (13%) on placebo. 13 (87%) showed 'no change' after placebo (two (13%) on clonazepam), while seven (44%) on clonazepam reported deterioration, often linked to side effects (n=6), suggesting potential benefit from lower dosing. Three N-of-1 trials with RCT responders saw two patients improve on clonazepam during double-blinding, but clinical evaluation deemed the improvements insufficient.

Conclusions: Our approach shows the feasibility and strength of combining conventional RCT and N-of-1 studies for therapeutic studies in populations with intellectual disabilities, distinguishing real treatment effects from expectation bias. Our findings suggest that clonazepam has no additional therapeutic value in ARID1B patients.

Trial registration number: EUCTR2019-003558-98, ISRCTN11225608.

Background: We aimed to estimate real-world evidence of the prevalence rate of genetic developmental and epileptic encephalopathies (DEEs) in the Italian population over a 11-year period.

Methods: Fifteen paediatric and adult tertiary Italian epilepsy centres participated in a survey related to 98 genes included in the molecular diagnostic workflows of most centres. We included patients with a clinical diagnosis of DEE, caused by a pathogenic or likely pathogenic variant in one of the selected genes, with a molecular diagnosis established between 2012 and 2022. These data were used as a proxy to estimate the prevalence rate of DEEs.

Results: We included 1568 unique patients and found a mean incidence proportion of 2.6 patients for 100.000 inhabitants (SD=1.13) with consistent values across most Italian regions. The number of molecular diagnoses showed a continuing positive trend, resulting in more than a 10-fold increase between 2012 and 2022. The mean age at molecular diagnosis was 11.2 years (range 0-75). Pathogenic or likely pathogenic variants in genes with an autosomal dominant inheritance pattern occurred in 77% (n=1207) patients; 17% (n=271) in X-linked genes and 6% (n=90) in genes with autosomal recessive inheritance. The most frequently reported genes in the survey were SCN1A (16%), followed by KCNQ2 (5.6%) and SCN2A (5%).

Conclusion: Our study provides a large dataset of patients with monogenic DEE, from a European country. This is essential for informing decision-makers in drug development on the appropriateness of initiatives aimed at developing precision medicine therapies and is instrumental in implementing disease-specific registries and natural history studies.

Background: Targeted cystic fibrosis (CF) carrier screening panels may lack sensitivity in non-European ancestry groups. This study aims to evaluate the sensitivity of various panels in Australian CF carriers identified through sequencing.

Methods: The following panels were evaluated in 869 CF carriers: Asuragen, Elucigene, Devyser, American College of Medical Genetics and Genomics and Victorian Clinical Genetics Services. Ancestry-specific CF carrier frequencies from population databases and Bayesian analysis were used to estimate post-test residual carrier risks.

Results: When variants with varying clinical consequences (VCC) were not considered, mean test sensitivity was highest in the Northern Europe group (95.6%) and lowest in the Southern Asia group (64.0%). The post-test residual carrier risk in the Northern Europe group was approximately 1 in 546, with only the Southern Asia group having a higher residual carrier risk of 1 in 179.

Conclusion: The Southern Asia group exhibited the lowest test sensitivity and the highest post-test residual carrier risk, surpassing that of the Northern Europe group. The inclusion or exclusion of VCC significantly impacted the calculated test sensitivities. Further research is suggested to better characterise CFTR variants in non-European ancestry groups and to determine which VCC, if any, should be included in carrier screening reports.