De novo CCNK missense variant associated with mild intellectual disability, subtle dysmorphism (hypertelorism, depressed/broad nasal bridge), and ventriculomegaly. This case broadens the clinical spectrum of CCNK-related neurodevelopmental disease and supports cyclin K as a disease gene; imaging and phenotype suggest a milder presentation compared with deletions.

ABSTRACTRobin sequence (RS) is a congenital condition characterized by micrognathia, glossoptosis, and upper airway obstruction, often occurring with cleft palate and syndromic conditions. The genetic basis of RS is heterogeneous, including monogenic variants and chromosomal rearrangements. This systematic review synthesizes the current genetic landscape of RS, analyzing data from 107 studies that employed various genetic testing methods, including chromosomal microarray (CMA), targeted sequencing, and whole exome sequencing (WES). A distinction is made between genetic variants identified in isolated versus non‐isolated RS. Pathogenic variants in genes as SOX9, SNRPB, SATB2, TGDS, RBM10, COL11A1, and COL2A1 are frequently identified, many of which are linked to non‐isolated RS. The most common chromosomal aberrations are deletions of 22q11.2 and 18q. Up‐to‐date genetic testing is essential to enable accurate diagnosis and personalized clinical care. With the growing use of whole genome sequencing (WGS) in clinical practice, the need for phenotype‐driven interpretation tools is increasing. Some platforms can prioritize gene relevance based on Human Phenotype Ontology (HPO) terms. Documenting both known and novel RS‐associated genes is therefore crucial to fully realize the diagnostic potential of WGS and support evidence‐based clinical decision‐making.

This study investigated clinical and genetic characteristics of Chinese pediatric patients with single large-scale mitochondrial DNA deletions (SLSMD). We analyzed 28 patients (July 2004-March 2025) using long-range PCR and next-generation sequencing. Spearman correlation and ANOVA assessed genotype-phenotype relationships. Patients (mean age 5.52 ± 3.96 years) exhibited multi-organ involvement (5.43 ± 1.87 organs). Common initial presentations included ocular (29%), neurologic, and endocrine dysfunction. Only 14.3% had the classic 4977 bp deletion, and 23 novel deletions were identified in 25 patients. Larger deletions correlated with more deleted MRC complexes (r = 0.516, p = 0.0123) and more deleted tRNAs (r = 0.534, p = 0.0103). Kearns-Sayre syndrome (KSS) patients had later onset (p = 0.0337), larger deletions (p = 0.0263), and greater tRNA/MRC complex (p = 0.0263, p = 0.0319) involvement than non-KSS patients. SLSMD in Chinese children primarily causes KSS, Pearson syndrome (PS), and progressive ophthalmoplegia with multi-organ involvement. Genotype-phenotype correlations exist, particularly between deletion size, onset age, and disease severity. KSS patients show distinct genetic and clinical profiles, suggesting slower progression. This study expands the known SLSMD spectrum and underscores mitochondrial testing in pediatric multi-organ disorders.

Dilated Cardiomyopathy (DCM) is a genetically heterogeneous condition of left ventricular dilation and systolic dysfunction, leading to heart failure. It is mostly inherited in a dominant pattern. Recessive inheritance has been rarely encountered. This study aims to outline the clinical and genetic characteristics associated with recessively inherited NRAP truncating variants in our highly consanguineous population. Twenty-three cases from 12 unrelated consanguineous families were recruited. Cardiological evaluation and genetic testing with exome sequencing (ES) were conducted in all cases, followed by segregation analysis of first-degree relatives. Genetic analysis with ES identified five unique homozygous truncating variants in NRAP in the affected cases. The segregation analysis detected a total of 23 homozygous and 21 heterozygous individuals. Out of the total homozygous cases, three were asymptomatic, while 20 exhibited symptoms with remarkable inter- and intrafamilial variability of the age of onset (range: 9 months to 47 years, median 10 years), seven of whom died (range: 9 months to 28 years, median 7 years). None of the heterozygous individuals showed symptoms. Of note, three homozygous cases underwent heart transplantation. Our findings show that truncating variants in NRAP are associated with reduced penetrance and clinical variability, suggesting a complex mechanism beyond simple Mendelian inheritance.

Exome sequencing (ES), originally developed to detect single nucleotide variants (SNVs), has been increasingly leveraged to detect copy number variants (CNVs) through read-depth analysis, enhancing diagnostic yield with minimal computational overhead. However, chromosomal microarray (CMA) testing remains widely used. To evaluate the utility of ES as a first-tier clinical diagnostic test, we compared the sensitivity of CNV detection by ES to that of CMA in individuals who underwent both tests, and developed triploidy screening based on ES data. ES identified most clinically relevant CNVs, with a 98.91% concordance for regions adequately captured. A retrospective analysis of CNVs detected from ES over a ~3-year period, comprising 1563 prenatal and 4884 postnatal cases, revealed CNVs in 3.8% of prenatal and 4.4% of postnatal samples. The relatively low percentage stems from the fact that most cases underwent CMA before ES. Pathogenic or likely pathogenic variants constituted 78.7% and 78.0% of these subgroups, with the remainder classified as variants of unknown significance. We highlight clinically relevant examples of CNVs across a range of sizes, including cases involving both CNVs and SNVs. The high consanguinity rate of the cohort allowed for systematic analysis of homozygous CNVs. Additionally, we demonstrate that ES can capture other diagnostic utilities traditionally associated with CMA, specifically uniparental disomy (UPD) and triploidy. Overall, our findings support ES as a robust, cost-effective alternative to CMA and advocate for its broader use as a first-tier diagnostic test for neurodevelopmental delay and congenital malformations, particularly until whole genome sequencing becomes more accessible and affordable.

Dihydrolipoamide dehydrogenase deficiency (DLDD) is a rare autosomal recessive disorder that typically affects the liver, brain, and muscle. Peripheral neuropathy has not been previously associated with this condition. We report a novel case of DLDD in a 20-year-old woman who presented with recurrent hepatic dysfunction and progressive sensory neuropathy. Clinical evaluation, electrophysiology, and nerve biopsy revealed a severe sensory axonal neuropathy with lipid accumulation. Genetic analysis identified compound heterozygous DLD variants (c.745G>T, p.G249C; c.1344_1347del, p.D448Efs*16), and Western blotting confirmed markedly reduced DLD protein in patient-derived fibroblasts. Treatment with a branched-chain amino acid (BCAA)-free formula, methylcobalamin, and thiamine led to complete resolution of vomiting and significant improvement in neuropathic symptoms, as confirmed by follow-up nerve conduction studies. This is the first report to link DLDD with a reversible sensory neuropathy, expanding the phenotypic spectrum of the disease. Our findings suggest a role for lipid dysregulation and metabolic imbalance in the pathogenesis of peripheral nerve involvement and support early targeted dietary therapy in patients with atypical DLDD presentations.

The BRCA2 c.156_157insAlu variant is a Portuguese founder mutation implicated in hereditary breast and ovarian cancer (HBOC). This study aims to determine its occurrence and clinical implications in the northern interior region of Portugal. A retrospective study of 571 individuals referred for HBOC genetic counseling and testing between 2021 and 2024 was conducted. Genetic screening was performed using next-generation sequencing of 27 hereditary cancer genes, with confirmatory PCR for BRCA2 c.156_157insAlu. Pathogenic or likely pathogenic variants were detected in 19.8% of participants, with BRCA1/2 variants accounting for 5.4%. The BRCA2 c.156_157insAlu variant was identified in 6 individuals (25% of all BRCA2 pathogenic variants identified), including breast cancer patients and asymptomatic carriers. Clinically, it was associated with early onset and contralateral breast cancer. Cascade testing and genetic counseling were offered to at-risk relatives. The BRCA2 c.156_157insAlu variant remains a significant contributor to HBOC in northern Portugal. Its high local proportion among BRCA2 variants supports the implementation of targeted genetic testing strategies, enhancing early detection and personalized cancer risk management.

Facioscapulo-humeral muscular dystrophy is characterized by a distinctive phenotype, although a wide range of clinical expressions is observed, possibly reflecting different disease progression rates or complex genetic mechanisms. To date, the diagnostic criteria for FSHD rely on identifying the genetic signature of the disease (reduced D4Z4 allele, permissive 4q allele, hypomethylation, and in some cases variants in modifier genes). However, interpreting genetic data requires careful correlation with the phenotype, especially in atypical cases. The study included a cohort of 42 patients with a D4Z4 contraction or belonging to a pedigree in which DRAs segregated but who were selected due to presenting atypical clinical features or an unexpected disease severity according to the Comprehensive Clinical Evaluation Form (CCEF). The 42 underwent 4q subtype analysis, DNA methylation assessment, whole-exome sequencing (WES) and segregation analysis. In 24 cases, WES identified likely pathogenic or pathogenic variants in genes associated with different neuromuscular disorders, in some cases possibly compatible with the observed phenotype. Methylation analysis proved useful in distinguishing asymptomatic and atypical cases, prompting differential diagnosis. Our results emphasize the importance of a detailed phenotypic characterization of patients with a suspicion of FSHD and, in the case of atypical phenotypes, the combination of D4Z4 sizing with other procedures such as WES.