BACKGROUND:Prenatal RhD screening enables risk stratification for RhD-associated hemolytic disease of the fetus and newborn (HDFN) and supports rational，evidence-based use of prophylactic anti-RhD immunoglobulin. However, noninvasive prenatal RhD screening remains challenging in the Chinese population, primarily due to population-specific RHD allelic diversity and the limited adaptability of current assay designs. METHODS:We developed and optimized a real-time PCR-based assay for noninvasive prenatal RHD genotyping, specifically designed to accommodate the spectrum of clinically relevant RHD alleles in the Chinese population. By simultaneously targeting RHD exons 5, 9, and 10, the assay enables detection of paternally inherited RHD alleles within a single analytical workflow. This assay facilitates accurate fetal RHD status determination in pregnancies involving the predominant RhD-negative alleles, including RHD*01N.01, RHD*01N.03, and RHD*01EL.01. RESULTS:The assay accurately predicted fetal RHD status across all simulated maternal genotypes, including those carrying non-deletion alleles such as RHD*01N.03 and RHD*01EL.01. CONCLUSION:This study presents a methodological framework for noninvasive prenatal RHD genotyping, specifically optimized for Chinese and other East Asian populations. Assay performance relies on distinct amplification patterns of population-specific RHD alleles across exons 5, 9, and 10. In addition, inclusion of exon 5 allows detection of RHD variants frequently observed in African populations, suggesting potential applicability across genetically diverse populations, pending further population-specific validation.
Imagawa-Matsumoto syndrome (IMMAS) is a rare overgrowth disorder caused by heterozygous loss-of-function variants in SUZ12, which encodes a core subunit of the Polycomb Repressive Complex 2 (PRC2). To date, fewer than 20 cases have been reported, and the molecular mechanisms underlying PRC2 dysfunction in IMMAS remain incompletely understood. Trio-based whole-exome sequencing (Trio-WES) was performed in a Chinese family presenting with overgrowth and dysmorphic features. The candidate variant was validated by Sanger sequencing and segregation analysis. AlphaFold 3 was used to predict the structural consequences of the variant. In vitro overexpression and protein assays were conducted to evaluate SUZ12 protein expression and subcellular localization. The proband exhibited global developmental delay, macrocephaly, hypertrichosis, and distinctive craniofacial dysmorphism. Trio-WES identified a heterozygous frameshift variant in SUZ12 (c.1244_1248del; p.Glu415GlyfsTer5). Computational modeling predicted that the truncating variant removes the ZnF and VEFS domains and may affect the predicted SUZ12–EZH2 interface. In vitro expression of the mutant construct confirmed the production of a truncated SUZ12 protein. Furthermore, peripheral blood mononuclear cells (PBMCs) from both the proband and her mother showed a substantial global reduction in H3K27me3 levels, consistent with impaired PRC2-mediated histone methylation in vivo. We report a Chinese family with Imagawa-Matsumoto syndrome harboring a SUZ12 frameshift variant (c.1244_1248del; p.Glu415GlyfsTer5). Our study expands the phenotypic spectrum associated with this variant and provides evidence consistent with impaired PRC2-mediated histone methylation.
Long QT syndrome (LQTS) is considered a primary cardiac ion channelopathy. Several studies have shown that myocardial functional alterations may occur in patients with LQTS type 3 (LQT3). However, it is currently unclear whether there is a specific relationship between phenotype and genotype. The aim of this study is to provide additional information on the phenotype and genotype of LQT3 caused by a novel delKKP 1504–1506 mutation in a Chinese family. The family came to our attention because of a sustained corrected QT interval (QTc) prolongation in a 14-year-old girl who had experienced a loss of consciousness with Mobitz type II atrioventricular block one year earlier. Three family members carrying the delKKP 1504–1506 mutation demonstrated a combination of infero-apical left ventricular aneurysms and prolonged QTc, and two members showed J-waves in the right precordial lead V2. This case suggests that the delKKP 1504–1506 mutation in SCN5A may not only lead to impaired impulse propagation in the conduction system and a prolonged QTc, but may also be associated with infero-apical ventricular aneurysms and J-wave syndromes, possibly corresponding to regional myocardial fibrosis.
Craniosynostosis is a genetically heterogeneous craniofacial disorder caused by the premature fusion of one or more cranial sutures. Pathogenic variants in TCF12, encoding a basic helix–loop–helix (bHLH) transcription factor, represent a major cause of autosomal dominant coronal craniosynostosis and are characterized by incomplete penetrance and marked phenotypic variability. However, clinical and molecular data from Asian pediatric populations remain limited. Trio-based whole-exome sequencing was performed on ten pediatric patients with cranial deformities and their parents. The identified TCF12 variants were classified according to the American College of Medical Genetics and Genomics (ACMG) guidelines and validated by Sanger sequencing. Detailed clinical and radiological data were collected. In addition, a comprehensive literature review was conducted to summarize previously reported TCF12 variants and associated phenotypes. Ten distinct heterozygous TCF12 variants were identified in ten unrelated pediatric patients, all of which were classified as pathogenic or likely pathogenic according to ACMG criteria. Six variants were inherited, and four occurred de novo. Seven patients had imaging-confirmed craniosynostosis, predominantly involving the coronal sutures (five bilateral and one unilateral), while one patient presented with multisuture craniosynostosis (left coronal and sagittal sutures). Three patients showed cranial deformities without radiographic evidence of suture fusion. Phenotypic heterogeneity and incomplete penetrance were observed, including a mildly affected parent. Most pathogenic variants were truncating variants distributed mainly across exons 14–19 and predicted to induce loss of function, either through nonsense-mediated mRNA decay or the production of truncated proteins lacking the entire C-terminal bHLH domain. Structural modeling analysis further indicated that the bHLH-domain-located missense variant p.Arg603Trp alters the local DNA-binding conformation of TCF12 and impairs its binding affinity to the E-box DNA motif. This study provides additional clinical and molecular data on TCF12-related craniosynostosis in a pediatric cohort from an Asian population. Our findings support haploinsufficiency as the central pathogenic mechanism, primarily driven by truncating variants affecting the C-terminal bHLH domain. The marked clinical heterogeneity, the presence of mild or evolving phenotypes, and incomplete penetrance observed in our cohort underscore the importance of early diagnosis and longitudinal clinical surveillance in affected families.
