Bi-Allelic Mutations in NUP205 and NUP210 Are Associated With Abnormal Cardiac Left-Right Patterning.

Circ Genom Precis Med. 2019;12:e002492. DOI: 10.1161/CIRCGEN.119. 002492 July 2019 Weicheng Chen, MD, PhD* Yuan Zhang, MD, PhD* Sunhu Yang, MD, PhD* Zhiwen Shi, PhD Weijia Zeng, BS Zhouping Lu, MD Xiangyu Zhou, PhD Defects in cardiac left-right (LR) patterning including situs inversus and heterotaxy are very rare with the prevalence ≈1/10 000 births.1 Although ciliadriven fluid flow plays an essential role in establishing LR asymmetry, the spectrum of genetic causes and the precise mechanisms remain largely unknown. Situs inversus totalis (SIT) is a congenital condition where the organs, especially heart, in the chest are arranged in a complete mirror-image reversal of the usual positions. Intriguingly, most individuals with SIT have no medical symptoms or complications, whereas the major visceral organs in patients with heterotaxy are distributed abnormally but not in a mirror image and accompanied by other malformations, mainly congenital heart disease. To explore novel causative genes involved in cardiac LR organization, we performed whole exome and genome sequencing on 61 family trios, including 42 SIT and 19 patients with heterotaxy. The ages of patients ranged from 21 weeks (fetus) to 76 years old. For studies of affected individuals and their families, signed and informed consent was obtained from all participants before study commencement. All the procedures in the study were approved by the Medical Ethics Committee of Children’s Hospital of Fudan University (2016–079). In 3 SIT trios (I, II, III) and one heterotaxy (IV) trio with complex congenital heart disease (Figure [A] through [D]), we identified bi-allelic missense mutations in nucleoporin (NUP) 205 (c.3131C>T, p.Thr1044Met and c.4829C>G, p.Pro1610Arg; NM_015135) and NUP210 (c.2197C>A, p.Ala1368Val and c.4103C>T, p.Phe733Thr; c.3194 G>T, p.Gly1065Val and c.3355G>A, p.Val1119Ile; c.1693G>A, p.Gly565Ser and c.3301G>A, p.Glu1101Lys; NM_024923; Figure [E])-that met the filter strategy (frequency <0.01 in gnomAD, protein-altering variants, recessive model). NUPs are a family of ≈30 proteins and comprise the main components of the nuclear pore complex in eukaryotic cells. These rare variants were highly conserved in different species and were predicted to be detrimental to protein function when evaluated by Poly-Phen2 and MutationTaster. Potential pathogenic copy number variations were excluded by chromosomal microarray analysis. We next generated induced pluripotent stem cells by reprogramming the peripheral blood sample of patient (I) carrying NUP205 (p.T1044M/P1610R) and a healthy age-matched situs solitus volunteer. We did not find gross abnormalities in cilia density and cilia length in the induced pluripotent stem cells. However, most mutant NUP205 in induced pluripotent stem cells that derived from patient (I) fail to mark the nuclear rim when compared with that of the health control (Figure [F]). Mutations of NUP205 and NUP93 have been shown to cause steroid-resistant nephrotic syndrome.2 Particularly, inner-ring components of the nuclear pore complex, NUP93, and NUP188 are specifically required for cardiac LR patterning.3 As a key inner-ring nucleoporin, NUP205 is a direct protein-interaction partner of NUP93; therefore, we performed co-IP assays in human retinal pigment epithelium RESEARCH LETTER