Abstract 16678: Multigenic Etiology of CHD With Heterotaxy Involving PCD and Cilia Genes
Introduction: We recently showed patients with CHD associated with heterotaxy can exhibit respiratory ciliary dysfunction (CD) similar to that of patients with primary ciliary dyskinesia (PCD) - a ciliopathy with airway mucociliary clearance defects. As both PCD and heterotaxy have a 1 in 10,000 incidence, the finding of CD in heterotaxy patients likely reflects the dual role of motile cilia in airway clearance and left-right patterning. Thus, we hypothesize heterotaxy may arise from mutations in PCD genes and other cilia related ciliome genes.
Methods and Results: CHD patients with heterotaxy, 13 with CD and 13 without CD (no-CD), were sequence captured followed by SOLiD sequencing at 40X coverage to identify sequence variants in all 13 PCD genes and nearly 1000 other ciliome genes. Coding variants were filtered against dbSNP and the 1000 Genomes databases, and novel coding variants (NCV) were validated by Sanger sequencing. Analysis of the 13 PCD genes revealed 10 NCV in 7 CD patients, and 5 NCV in 3 no-CD patients. The 3 PCD patients had 5 NCV, with 2 siblings having homozygous CCDC39 mutation (1072delA) known to cause PCD. Interestingly, CD-heterotaxy patient 9002 was heterozygous for the most common pathogenic DNAI1 mutation, IVS1+2_3insT, a disease NCV not seen in the general population. As PCD is a recessive disorder, we evaluated NCVs found in DNAH6, a motor dynein gene not yet demonstrated to cause PCD. DNAH6 NCVs were found in 9002 and one other CD and one PCD patient, but not in any no-CD patient. Dnah6 morpholino (MO) knockdown (KD) in zebrafish embryos showed laterality defects and phenotypes consistent with heterotaxy, suggesting a role in CD and heterotaxy.
Conclusion: Our study showed heterotaxy patients with CD can have heterozygous NCVs in PCD genes, including known disease causing DNAI1 mutation. Functional analysis with zebrafish MO showed DNAH6 KD can cause heterotaxy. We propose DNAH6/DNAI1 double heterozygous mutation may contribute to CD and heterotaxy.
- © 2011 by American Heart Association, Inc.