High prevalence of respiratory ciliary dysfunction in congenital heart disease patients with heterotaxy

Abstract

Background: Patients with congenital heart disease (CHD) and heterotaxy show high postsurgical morbidity/mortality, with some developing respiratory complications. Although this finding is often attributed to the CHD, airway clearance and left-right patterning both require motile cilia function. Thus, airway ciliary dysfunction (CD) similar to that of primary ciliary dyskinesia (PCD) may contribute to increased respiratory complications in heterotaxy patients.

Methods and results: We assessed 43 CHD patients with heterotaxy for airway CD. Videomicrocopy was used to examine ciliary motion in nasal tissue, and nasal nitric oxide (nNO) was measured; nNO level is typically low with PCD. Eighteen patients exhibited CD characterized by abnormal ciliary motion and nNO levels below or near the PCD cutoff values. Patients with CD aged >6 years show increased respiratory symptoms similar to those seen in PCD. Sequencing of all 14 known PCD genes in 13 heterotaxy patients with CD, 12 without CD, 10 PCD disease controls, and 13 healthy controls yielded 0.769, 0.417, 1.0, and 0.077 novel variants per patient, respectively. One heterotaxy patient with CD had the PCD causing DNAI1 founder mutation. Another with hyperkinetic ciliary beat had 2 mutations in DNAH11, the only PCD gene known to cause hyperkinetic beat. Among PCD patients, 2 had known PCD causing CCDC39 and CCDC40 mutations.

Conclusions: Our studies show that CHD patients with heterotaxy have substantial risk for CD and increased respiratory disease. Heterotaxy patients with CD were enriched for mutations in PCD genes. Future studies are needed to assess the potential benefit of prescreening and prophylactically treating heterotaxy patients for CD.

Figures

Figure 1

Laterality and cardiovascular defects in heterotaxy patients. Patients recruited for study; 5 did not complete study. AVC indicates atrioventricular canal; DORV, double outlet right ventricle; SV, single ventricle; CD, ciliary dysfunction.

Figure 2

Ciliary motion in nasal epithelia from heterotaxy and PCD patients. A, Abundant cilia (arrow) were observed in patient 9033 exhibiting normal ciliary motion. B, Paucity of cilia (arrow) in 9027 with CD. C, No cilia found in nasal epithelia (arrow) of 9004. D, Healthy control showing normal motion with full forward and recovery strokes (online-only Data Supplement Movie I). E, PCD patient 9028 has stiff motion with shortened stroke and minimal ciliary bending. F, Patient 9011 with heterotaxy and CD exhibit shortened forward stroke and wavy recovery stroke with limited bending of the distal ciliary exoneme (online-only Data Supplement Movie V). Scale bar=10 μm.

Figure 3

Nasal nitric oxide measurements in heterotaxy patients. A through C, nNO measurements from each patient are plotted in 3 age groups. D through F, Box plots show interquartile range (IQR) from 25 to 75th percentile, with median denoted by bold line. Whiskers denote minimum-maximum value not >1.5 times the IQR value, with outlying values indicated by squares. *The nNO values for PCD patients <1 and 1 to 6 years of age were adapted from Chawla et al. CD indicates ciliary dysfunction; PCD, primary ciliary dyskinesia.

Figure 4

Novel coding variants in PCD genes. More NCVs in PCD genes were observed in heterotaxy patients with CD and PCD patients than healthy controls. *Probability values obtained in comparison with controls. Statistical analysis was performed with the Fisher exact test (A) or the Kruskal-Wallis test followed by Wilcoxon rank sum test (B) with P<0.025 considered significant based on Bonferroni correction.