Background/Objectives: Pediatric hypertrophic cardiomyopathy (HCM) is the most common genetic myocardial disorder in children and a leading cause of sudden cardiac death (SCD) among the young. Its phenotypic variability, driven by incomplete penetrance and variable expressivity, presents significant challenges in diagnosis and clinical management. Methods: In this study, we report a unique case of a 16-month-old female diagnosed with HCM caused by a rare genetic deletion. Molecular analysis was performed using a multigene panel and chromosomal microarray analysis (CMA). Results: Molecular tests identified a 30 kb deletion encompassing the MYH6 and MYH7 genes. These genes are critical components of sarcomeric architecture, with known associations to HCM and other cardiomyopathies. Conclusions: This case underscores the clinical and genetic heterogeneity of HCM, highlighting the importance of considering genomic deletions involving key sarcomeric genes in the diagnostic evaluation.

Neurodevelopmental disorders (NDDs) are a heterogeneous group of conditions characterised by impairments in cognition, motor function, behaviour, and social interaction. Their genetic basis is highly diverse, and next-generation sequencing has become central to improving diagnostic yield. We retrospectively analysed 94 paediatric patients (0–18 years) with NDDs referred to the Paediatric and Rare Diseases Clinic, Microcitemico Hospital “A. Cao,” between January 2019 and July 2024. Each patient underwent detailed clinical evaluation and whole-exome sequencing (WES). Variants were prioritised according to ACMG guidelines. Gene burden analysis of rare predicted loss-of-function variants was performed using the Cohort Allelic Sums Test to detect enrichment in NDD cases relative to controls. WES identified 12 pathogenic variants, 16 likely pathogenic variants, and 10 variants of uncertain significance. Autosomal dominant disorders were the most frequent (n = 35 patients), while autosomal recessive and X-linked dominant conditions were identified in a single case each. The findings of this study further highlight the importance of WES in identifying novel genetic variants and in providing explanations for previously unexplained NDD cases. Moreover, the Cohort Allelic Sums Test (CAST) demonstrated that rare variants are enriched in genes implicated in neuronal development in affected individuals.

Background: Houge-Janssens syndrome 1 is a condition with onset in early childhood caused by heterozygous pathogenic variants in the PPP2R5D gene, which encodes a B56 regulatory subunit of the serine/threonine protein phosphatase 2A (PP2A). There is evidence that the PP2A-PPP2R5D complex is involved in regulating the phosphatidylinositol 3-kinase (PI3K)/AKT signalling pathway, which is crucial for several cellular processes, including the pathogenesis and progression of haemangiomas. Case presentation: We report the first PPP2R5D-related neurodevelopmental disorder case from Sardinia, a child with transient hypoglycaemia, facial dysmorphisms, and multiple haemangiomas. Whole Exome Sequencing analysis confirmed the clinical suspicion, detecting the presence of the de novo missense variant c.592G>A in the PPP2R5D gene. Conclusions: Haemangiomas have never been linked to the syndromic phenotype of the PPP2R5D-associated disorder. The close correlation between the PP2A enzyme and the PI3K/AKT signalling pathway suggests the possible correlation between its dysfunction and activation of haemangiogenesis. Our report highlights a possible link between the PPP2R5D-related disorder and altered angiogenesis, characterizing diffuse haemangiomas as a possible novel phenotypic trait of this condition.

Background: Genome-wide ploidy abnormalities (GWPA) constitute a distinct and clinically significant class of chromosomal errors that arise during human preimplantation development. However, the developmental origins and prevalence of GWPA remain incomplete and poorly understood. Methods: To evaluate the frequency and origin of GWPA in human embryos, we have retrieved preimplantation genetic testing (PGT) haplotyping data, derived from 3798 blastomere and 3593 trophectoderm biopsies. Prior haplotype reconstruction and determination of parental origin were performed using B-allele frequency-aware haplotyping (haplarithmisis). Results: GWPA were detected in 113 biopsies: 81 cleavage-stage embryos and 32 blastocysts. Genome-wide loss of heterozygosity of maternal origin was the most frequent abnormality. Triploidy was the second most common aberration present in 35 embryos: 24 cleavage-stage embryos and 11 blastocysts, with the majority resulting from maternal meiosis II errors. In addition, we uncover less-characterized abnormalities, providing new insights into the chromosomal mechanisms driving early human embryonic development. Conclusions: GWPA occur in 2.16% of cleavage-stage and 0.89% of blastocyst-stage ICSI embryos, showing a strong selection against GWPA during preimplantation development. This study also demonstrates that using appropriate methods to detect GWPA when screening ICSI embryos can help prevent the transfer of nonviable embryos.