From phenotype to mechanism: Prenatal spectrum of NKAP mutation-related disorder and its pathogenesis inducing congenital heart disease.

NKAP mutations are associated with Hackmann-Di Donato-type X-linked syndromic intellectual developmental disorder (MRXSHD, MIM: #301039). Here, we elucidate the potential prenatal manifestation of NKAP mutation-associated disorder for the first time, alongside revealing the relationship between NKAP mutations and congenital heart defect (CHD) in the Chinese population. An NKAP mutation (NM_024528.4: c.988C>T, p.Arg330Cys) was identified in two foetuses presenting with CHD. Subsequent mechanistic exploration revealed a marked downregulation of NKAP transcription within HEK293T cells transfected with NKAP p.R330C. However, no significant change was observed at the protein level. Moreover, the mutation led to a dysregulation in the transcription of genes associated with cardiac morphogenesis, such as DHRS3, DNAH11 and JAG1. Additionally, our research determined that NKAP p.R330C affected Nkap protein intra-nuclear distribution, and binding with Hdac3. Summarily, our study strengthens NKAP mutations as a cause of CHD and prompts the reclassification of NKAP p.R330C as likely pathogenic, thereby establishing a prospective prenatal phenotypic spectrum that provides new insight into the prenatal diagnosis of CHD. Our findings also provide evidence of NKAP p.R330C pathogenicity and demonstrate the potential mechanism by which p.R330C dysregulates cardiac developmental gene transcription by altering Nkap intra-nuclear distribution and obstructing the interaction between Nkap and Hdac3, thereby leading to CHD.

The yield of SNP microarray analysis for fetal ultrasound cardiac abnormalities.

BACKGROUND: Chromosomal microarray analysis (CMA) has emerged as a critical instrument in prenatal diagnostic procedures, notably in assessing congenital heart diseases (CHD). Nonetheless, current research focuses solely on CHD, overlooking the necessity for thorough comparative investigations encompassing fetuses with varied structural abnormalities or those without apparent structural anomalies. OBJECTIVE: This study sought to assess the relation of single nucleotide polymorphism-based chromosomal microarray analysis (SNP-based CMA) in identifying the underlying causes of fetal cardiac ultrasound abnormalities. METHODS: A total of 2092 pregnant women who underwent prenatal diagnosis from 2017 to 2022 were included in the study and divided into four groups based on the presence of ultrasound structural abnormalities and the specific type of abnormality. The results of the SNP-Array test conducted on amniotic fluid samples from these groups were analyzed. RESULTS: Findings from the study revealed that the non-isolated CHD group exhibited the highest incidence of aneuploidy, overall chromosomal abnormalities, and trisomy 18, demonstrating statistically significant differences from the other groups (p < 0.001). Regarding the distribution frequency of copy number variation (CNV) segment size, no statistically significant distinctions were observed between the isolated CHD group and the non-isolated CHD group (p > 0.05). The occurrence rates of 22q11.2 and 15q11.2 were also not statistically different between the isolated CHD group and the non-isolated congenital heart defect group (p > 0.05). CONCLUSION: SNP-based CMA enhances the capacity to detect abnormal CNVs in CHD fetuses, offering valuable insights for diagnosing chromosomal etiology and facilitating genetic counseling. This research contributes to the broader understanding of the utility of SNP-based CMA in the context of fetal cardiac ultrasound abnormalities.

The role of DNA damage response in human embryonic stem cells exposed to atmospheric oxygen tension: Implications for embryo development and differentiation.

Previous retrospective cohort studies have found that, compared with oxygen tension in the uterus and fallopian tubes (2 %-8 %), exposure of pre-implantation embryos to atmospheric oxygen tension (AtmO2, 20 %) during assisted reproductive technology(ART) can affect embryo quality, pregnancy outcomes and offspring health. However, current research on the effects and mechanisms of AtmO2 on the development of embryos and offspring is mainly limited to animal experiments. Human embryonic stem cells (hESCs) play a special and irreplaceable role in the study of early human embryonic development. In this study, we used hESCs as a model to elucidate the possible effects and mechanisms of AtmO2 exposure on human embryonic development. We found that exposure to AtmO2 can reduce cell viability, produce oxidative stress, increase DNA damage, initiate DNA repair, activate autophagy, and increase cell apoptosis. We also noticed that approximately 50 % of hESCs survived, adapted and proliferated through high expression of self-renewal and pluripotency regulatory factors, and affected embryoid body differentiation. These data indicate that hESCs experience oxidative stress, accumulation of DNA damage, and activate DNA damage response under the selective pressure of AtmO2.Some hESCs undergo cell death, whereas other hESCs adapt and proliferate through increased expression of self-renewal genes. The current findings provide in vitro evidence that exposure to AtmO2 during the early preimplantation stage negatively affects hESCs.