Journal of Medical Genetics最新文献

Background: Achondroplasia is the most common form of disproportionate short stature and is associated with reduced life expectancy. It is not clear to what extent cardiovascular disease (CVD) is responsible for this. The primary aim of this systematic review was to identify the prevalence of CVD in individuals with achondroplasia.

Methods: A systematic review of the literature was conducted in accordance with PRISMA guidelines by two independent reviewers using two databases. There were no language or date restrictions. The search strategy consisted of the terms: "achondroplasia" AND "vascular" OR "cardiovascular" OR "metabolic". Quality assessment was undertaken using the Critical Appraisal Skills Programme checklists.

Results: In total, 300 articles which met the inclusion criteria were screened. Of these, 33 (11%) were included for analysis published between 1972 and 2023, encompassing >5000 individuals with achondroplasia. Techniques of cardiovascular assessment included measures of adiposity in 20 (61% of included studies), metabolic parameters in 9 (27%), blood pressure in 6 (18%), physical activity in 6 (18%) and morbidity and mortality secondary to CVD in 5 (15%). People with achondroplasia were found to be at increased risk of obesity, impaired glucose regulation and hypertension.

Discussion: There is significant heterogeneity in the outcomes measured to assess CVD risk in people with achondroplasia. As a result, there remain significant gaps in the literature regarding the development of CVD in individuals with this condition. Longitudinal studies offering detailed cardiovascular phenotyping should be considered in people with achondroplasia to mitigate the risks of CVD-related morbidity and mortality.

Background: Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant gastric cancer associated with germline CDH1 mutations. Carriers of CDH1 mutations have a higher risk of developing gastric cancer at a younger age, highlighting the need for a phenotypic feature for early diagnosis and management.

Methods: We analysed 121 patients with gastric cancer who underwent genetic testing at the National Cancer Center in China. CDH1 mutation status was assessed using next-generation sequencing. Fisher's exact test and Mann-Whitney U test were performed to compare clinicopathological features between CDH1-mutated and non-mutated patient groups.

Results: Among 121 index cases, three CDH1 germline mutation carriers (2.5%) were identified. Mutation carriers were diagnosed at a significantly younger age compared with non-carriers (p<0.05). Notably, two patients in our cohort exhibited congenital tooth agenesis, a phenotypical feature rarely reported in patients with HDGC and previously undocumented in East Asian cohorts.

Conclusion: Congenital tooth agenesis represents a phenotypic manifestation associated with CDH1 germline mutations. Awareness of such features could enhance recognition of high-risk individuals and support genetic counselling and surveillance strategies. Further studies are needed to confirm these associations.

Background: Pathogenic variants in the protection of telomerase 1 (POT1) gene are associated with predisposition to a broad spectrum of malignancies, although the specific genotype-phenotype correlation has not yet been fully elucidated. To further characterise the phenotypic spectrum, we describe six families with germline POT1 variants and evaluate existing literature to highlight the possible association between variants in POT1, telomere dysregulation and predisposition to malignant central nervous system (CNS) tumours.

Methods: Genetic analyses were performed using an Illumina sequencing platform. All variants were examined by in silico analysis in Alamut as well as Rare Exome Variant Ensemble Learner (REVEL), and one variant was additionally examined by RNA analysis.Telomere length assessment was performed through RepeatDX Europe.

Results: We identified four missense and two frameshift POT1 germline variants: c.255G>C, p.(Lys85Asn), c.322G>A, p.(Gly108Arg), c.323G>A, p.(Gly108Glu), c.676C>T, p.(His226Tyr), c.707del, p.(Gly236Glufs*16) and c.709del, p.(Ser237Alafs*15). The variants c.255G>C and c.322G>A were observed in two patients with astrocytoma and c.676C>T in a patient with oligodendroglioma, corresponding to the most prevalent CNS tumour histopathology described in POT1 carriers in previous publications. Longer telomeres were found in probands with the CNS tumour phenotype.

Conclusion: Our findings support a possible association between pathogenic POT1 germline variants and increased risk of CNS tumours mainly oligodendroglioma, astrocytoma and glioblastoma. We highlight the potential importance of missense variants and telomeric measurement in tailoring of surveillance and advocate further studies to guide future personalised surveillance strategies.

Neuroendocrine tumours (NETs) are increasingly associated with Lynch syndrome (LS). In this autosomal dominant cancer predisposition syndrome, a somatic mutation in addition to a germline pathogenic variant is required for tumour development. We describe the case of a middle-aged female patient with LS with a known germline MLH1 mutation who was diagnosed with Cushing's syndrome. An ectopic adrenocorticotropic hormone (ACTH) producing carcinoid tumour of the lung with lymph node metastases was found and resected. Immunohistochemical analysis showed loss of MLH1/PMS2 expression, and genetic analysis confirmed a deletion of the entire MLH1 gene, acting as the second hit for tumour formation. This provides unequivocal evidence of the tumour's association with LS. Only 30 cases of NETs in LS have been described in the literature, most of them of gastrointestinal origin. We describe the first bronchopulmonary NET in a patient with LS, broadening the spectrum of LS tumours, and the first ACTH-producing tumour in LS.

Background: Pathogenic gain-of-function or dominant-negative effect missense variations in ACTB are associated with a neurodevelopmental disorder characterised by intellectual disability (ID), seizures, sensorineural hearing loss, cerebral, renal and ocular abnormalities and dysmorphic features (Baraitser-Winter cerebrofrontofacial syndrome). ACTB encodes beta-actin, a highly conserved protein involved in cell motility, structure and integrity. Deletions including ACTB, and, more rarely, single-nucleotide loss-of-function variants in ACTB have been described in patients with a distinct phenotype including developmental delay, ID, microcephaly, growth restriction, cardiac and renal abnormalities and dysmorphic features.

Methods: We collected 14 individuals and 1 fetus carrying a heterozygous deletion including ACTB, and 4 individuals with a heterozygous truncating variant. Genotypic and phenotypic data were analysed. Furthermore, a comprehensive review of all cases reported to date was also undertaken.

Results: Twelve out of 17 individuals presented with ID, and 3 out of 17 with learning disabilities. Speech delay and behavioural abnormalities were observed in 15 out of 17 and 12 out of 17 individuals, respectively, motor delay in 9 out of 17 and growth restriction in 9 out of 18. Most of the individuals (13/18) had recognisable dysmorphic features. 11 anomalies were de novo, except for 1 deletion inherited from the mother. The size of the deletion varied from 125 kb to 1.6 Mb and could result from a fork stalling and template switching.

Conclusion: This study allowed us to better characterise the phenotype associated with the haploinsufficiency of ACTB, underlying the high prevalence of neurodevelopmental disorders (ID, speech and motor delay, behavioural abnormalities) and growth restriction in this recognisable syndrome.

Purpose and scope: The aim of this position statement is to provide recommendations aimed at Canadian reproductive care clinicians and genetics professionals regarding the use of reproductive carrier screening for autosomal recessive and X-linked recessive conditions.

Methods of statement development: A multidisciplinary expert group was assembled to review the existing literature on reproductive carrier screening for autosomal recessive and X-linked recessive conditions and make recommendations relevant to the Canadian context. The statement was circulated for comment to the membership of the Canadian College of Medical Geneticists (CCMG) and Canadian Association of Genetic Counsellors (CAGC), and multiple family physician reviewers. Feedback from these groups was incorporated, and the final position statement was approved by the CCMG Board of Directors on 5 December 2024 and the CAGC Board of Directors on 14 April 2025.

Results and conclusions: Routinely offered pan-ethnic reproductive carrier screening via a provincial or territorial programme is recommended for a limited panel of relatively common and severe childhood onset genetic conditions, based on Canadian experience with ethnicity-based testing: cystic fibrosis, fragile X syndrome, spinal muscular atrophy, haemoglobinopathies and founder mutations for Tay-Sachs disease, Canavan disease and familial dysautonomia. Provincial/territorial programmes must be developed to provide oversight, ensure appropriate resourcing and manage education and roll-out. Maintaining regional ethnicity-based screening programmes is also recommended, where relevant. Publicly funded population-level expanded carrier screening is not recommended at this time.

Background: Neurofibromatosis type 1 (NF1) is one of the most frequent genetic disorders. NF1 is caused by dominant loss-of-function pathogenic variants (PVs) of the tumour-suppressor gene NF1, which encodes neurofibromin, a negative regulator of rat sarcoma proteins. NF1 is an autosomal dominant disorder with complete penetrance, but a highly variable expression. Identification of genotype-phenotype correlations is challenging because of the wide clinical variability, the progressive nature of the disorder and the extreme diversity of the mutation spectrum. Only a few NF1 point variants have been associated with a specific phenotype in NF1 patients.

Methods: We investigated a large, well-phenotyped NF1 cohort.

Results: We report analyses of genotype-phenotype correlations in 112 NF1 patients with specific NF1 point variants: p.Arg1809 missense variants were associated with a mild form of NF1 (n=24), while a more severe phenotype was associated with codons 844-848 (n=27), p.Arg1276 (n=25) and p.Lys1423 (n=35) missense variants. We describe a new correlation for p.Arg1204 missense variants (n=11), with no neurofibroma observed in patients. Functional studies will be critical for drawing conclusions on the potential hypomorphic or dominant-negative effects of these variants.

Conclusion: The current data confirms several genotype-phenotype correlations in NF1, which may be relevant to the management and surveillance of NF1 patients with specific NF1 PVs.

Background: Heterozygous PURA (Purine-rich element-binding protein A) variants cause PURA syndrome, a neurodevelopmental disorder characterised by hypotonia, seizures and intellectual disability. Previous studies have focused on the effect of the PURA variant in the cytoplasmic location, but nuclear mislocalisation remains to be explored.

Methods: We identified a de novo heterozygous frameshift variant (c.442del, p.L148Wfs*77) via trio whole-exome sequencing in one child suspected of PURA syndrome due to intellectual disability. Functional analyses included structural modelling, subcellular localisation assays, RNA-seq, CUT&Tag and DNA unwinding assays.

Results: The variant disrupts PURA repeats II-III, causing aberrant nuclear mislocalisation. RNA-seq revealed 688 differentially expressed genes enriched in neurodevelopmental pathways. CUT&Tag analysis revealed that PURA and Pol II exhibit enhanced binding at transcription start sites in cells expressing the variant, indicating dysregulated transcriptional engagement. Despite retained nucleic acid binding, the variant impaired DNA unwinding partly due to disrupted repeat III-mediated homodimerisation.

Conclusions: Nuclear mislocalisation of the PURA variant dysregulates transcriptional balance and impairs DNA unwinding, linking PURA's structural integrity to neurodevelopmental deficits. This highlights PURA's dual roles in cytoplasmic RNA regulation and nuclear transcription, providing mechanistic insights into PURA syndrome pathogenesis.

Li-Fraumeni syndrome and Birt-Hogg-Dubé syndrome are distinct cancer predisposition syndromes caused by germline pathogenic variants (GPVs) in TP53 and FLCN, respectively. Multilocus inherited neoplasia alleles syndrome (MINAS) describes the co-occurrence of GPVs in two or more cancer predisposition genes. We present a unique case of a boy aged 16 years with multiple, very early onset atypical cutaneous fibrous histiocytomas (ACFHs), diagnosed with MINAS due to de novo TP53 and paternally inherited FLCN GPVs. This case is the first reported association of ACFH with germline TP53 and FLCN pathogenic variants. This paper highlights the importance of considering MINAS in patients with unusual tumour presentations. We discuss the clinical, histopathological and genetic findings, emphasising the need for comprehensive genetic testing and personalised surveillance in such cases.