Association of copy number variation in X chromosome-linked PNPLA4 with heterotaxy and congenital heart disease.

BACKGROUND: Heterotaxy (HTX) is a thoracoabdominal organ anomaly syndrome and commonly accompanied by congenital heart disease (CHD). The aim of this study was to analyze rare copy number variations (CNVs) in a HTX/CHD cohort and to examine the potential mechanisms contributing to HTX/CHD. METHODS: Chromosome microarray analysis was used to identify rare CNVs in a cohort of 120 unrelated HTX/CHD patients, and available samples from parents were used to confirm the inheritance pattern. Potential candidate genes in CNVs region were prioritized via the DECIPHER database, and PNPLA4 was identified as the leading candidate gene. To validate, we generated PNPLA4-overexpressing human induced pluripotent stem cell lines as well as pnpla4-overexpressing zebrafish model, followed by a series of transcriptomic, biochemical and cellular analyses. RESULTS: Seventeen rare CNVs were identified in 15 of the 120 HTX/CHD patients (12.5%). Xp22.31 duplication was one of the inherited CNVs identified in this HTX/CHD cohort, and PNPLA4 in the Xp22.31 was a candidate gene associated with HTX/CHD. PNPLA4 is expressed in the lateral plate mesoderm, which is known to be critical for left/right embryonic patterning as well as cardiomyocyte differentiation, and in the neural crest cell lineage. Through a series of in vivo and in vitro analyses at the molecular and cellular levels, we revealed that the biological function of PNPLA4 is importantly involved in the primary cilia formation and function via its regulation of energy metabolism and mitochondria-mediated ATP production. CONCLUSIONS: Our findings demonstrated a significant association between CNVs and HTX/CHD. Our data strongly suggested that an increased genetic dose of PNPLA4 due to Xp22.31 duplication is a disease-causing risk factor for HTX/CHD.

Analysis of the CHD7 gene mutations in patients of congenital heart disease with extracardiac malformations.

Background: Congenital heart disease (CHD) is a common birth defect, and is frequently accompanied with extracardiac malformations (ECM). Uncovering the genetic etiology of CHD may have a meaningful impact on disease management. De novo variants have been proven to be associated with CHD. Methods: Whole exome sequencing was performed for 4 unrelated CHD families with extracardiac malformations, candidate genes were screened by using stringent bioinformatics analysis, and the obtained variants were confirmed by Sanger sequencing. RT-PCR and Sanger sequencing were used to investigate the influence of a splice variant on pre-mRNA splicing. Further targeted sequencing was conducted to investigate the association of CHD7 variants with sporadic CHD. Results: Four novel heterozygous loss-of-function CHD7 mutations were found by using stringent bioinformatics analysis: the frameshift mutation c.1951_1952delAAinsT (p.L651X) in family #1, the nonsense mutations c.2913C>G (p.Y971X) in family #2 and c.3106C>T (pA1036X) in family #3, and the splicing mutation c.4353+4_4353+12delinsGCCCA in family #4. Sanger sequencing confirmed that these were all de novo mutations and were absent in the healthy parents and siblings of the probands. Further studies revealed that the splice mutation c.4353+4_4353+12delinsGCCCA influenced CHD7 mRNA splicing in vivo. Targeted sequencing found 23 rare mutations in 1,155 sporadic CHD patients. Conclusions: The findings here confirm that de novo loss-of-function variants of the CHD7 gene are the genetic cause of familial CHD with extracardiac malformations and the spectrum of pathogenic CHD7 variants in sporadic CHD is expanded.

Clinical implications of respiratory ciliary dysfunction in heterotaxy patients with congenital heart disease: elevated risk of postoperative airway complications.

Objective: Cardiac surgery in Congenital Heart Disease-Heterotaxy (CHD-HTX) patients often leads to increased postoperative airway complications. Abnormal respiratory ciliary function, resembling primary ciliary dyskinesia, has been observed. We expanded the sample size by retrospectively reviewing Ciliary Dysfunction (CD) in CHD-HTX patients to verify the increased risk of post-surgical respiratory complications. Methods: We conducted a retrospective review of 69 CHD-HTX patients undergoing cardiac surgery, assessing abnormal respiratory function using nasal nitric oxide (nNO) levels and nasal ciliary motion observed in video microscopy. Data collected included demographics, surgical details, postoperative complications, length of stay, ICU hours, salvage procedures, intubation duration, and mortality. Results: The CD and no-CD cohorts exhibited notable similarities in risk adjustment in Congenital Heart Surgery-1 (RACHS-1) risk categories, age at the time of surgery, and the duration of follow-up evaluations. We observed a trend toward an increased length of post-operative stay in the CD group (15.0 vs. 14.0; P = 0.0017). CHD-HTX patients with CD showed significantly higher rates of respiratory complications (70% vs. 44.4%; P = 0.008). There were no notable variances observed in postoperative hospitalization duration, mechanical ventilation period, or surgical mortality. Conclusion: Our findings suggest that CHD-HTX patients with CD may face an elevated risk of respiratory complications. These results offer guidance for perioperative management and serve as a reference for further pathological studies.

A novel de novo PDE4D gene mutation identified in a Chinese patient with acrodysostosis.

Acrodysostosis is an extremely rare disorder at birth, that is, characterized by skeletal dysplasia with short stature and midfacial hypoplasia, which has been reported to be caused by PDE4D and PRKAR1A gene mutations. Here, a Chinese boy with acrodysostosis, ventricular septal defect, and pulmonary hypertension was recruited for our study, and his clinical and biochemical characteristics were analyzed. A novel de novo heterozygous missense mutation (NM_001104631: c.2030A>C, p.Tyr677Ser) of the PDE4D gene was detected by whole exome sequencing and confirmed by Sanger sequencing. The c.2030A>C (p.Tyr677Ser) variant was located in exon 15 of the PDE4D gene, predicted to be damaging by a functional prediction program and shown to be highly conserved among many species. Further functional analysis showed that the p.Tyr677Ser substitution changes the function of the PDE4D protein, affects its subcellular localization in transfected cells, increases PDE4 activity in the regulation of cAMP signaling and affects cell proliferation. Our study identified a novel de novo PDE4D mutation in acrodysostosis of Chinese origin that not only contributes a deeper appreciation of the phenotypic characteristics of patients with PDE4D mutations but also expands the spectrum of PDE4D mutations.