Case Report: DNAAF4 Variants Cause Primary Ciliary Dyskinesia and Infertility in Two Han Chinese Families

Abstract

Background: Primary ciliary dyskinesia (PCD) is a rare genetic disorder, predominantly autosomal recessive. The dynein axonemal assembly factor 4 (DNAAF4) is mainly involved in the preassembly of multisubunit dynein protein, which is fundamental to the proper functioning of cilia and flagella. There are few reports of PCD-related pathogenic variants of DNAAF4, and almost no DNAAF4-related articles focused on sperm phenotype. Moreover, the association between DNAAF4 and scoliosis has never been reported, to the best of our knowledge.Materials and Methods: We recruited two patients with a clinical diagnosis of PCD. One came from a consanguineous and another from a non-consanguineous family. Clinical data, laboratory test results, and imaging data were analyzed. Through whole exome sequencing, immunofluorescence, electron microscopy, high-speed video microscopy analysis, and hematoxylin–eosin (HE) staining, we identified the disease-associated variants and validated the pathogenicity.Results: Proband 1 (P1, F1: II-1), a 19-year-old man, comes from a non-consanguineous family-I, and proband 2 (P2, F2: II-1), a 37-year-old woman, comes from a consanguineous family-II. Both had sinusitis, bronchiectasis, situs inversus, and scoliosis. P1 also had asthenoteratozoospermia, and P2 had an immature uterus. Two homozygous pathogenic variants in DNAAF4 (NM_130810.4), c.988C > T, p.(Arg330Trp), and DNAAF4 (NM_130810.4), c.733 C > T, p.(Arg245*), were identified through whole exome sequencing. High-speed microscopy analysis showed that most of the cilia were static in P1, with complete static of the respiratory cilia in P2. Immunofluorescence showed that the outer dynein arms (ODA) and inner dynein arms (IDA) were absent in the respiratory cilia of both probands, as well as in the sperm flagellum of P1. Transmission electron microscopy revealed the absence of ODA and IDA of respiratory cilia of P2, and HE staining showed irregular, short, absent, coiled, and bent flagella.Conclusion: Our study identified a novel variant c.733C > T, which expanded the spectrum of DNAAF4 variants. Furthermore, we linked DNAAF4 to asthenoteratozoospermia and likely scoliosis in patients with PCD. This study will contribute to a better understanding of PCD.

Congenital hemivertebrae combined with situs inversus totalis: A rare case report

“…The majority of them were right-handed, suggesting that the vertebral rotation is related to visceral position rather than hand use habits. Generally, patients with idiopathic scoliosis exhibit right thoracic curve and vertebrae's rightward rotation; however, in 2 studies of 4 patients with idiopathic scoliosis and situs inversus by Guo et al [9] and Lu et al, [12] the thoracic curve bent to the left and the vertebrae of mid and lower thoracic vertebrae rotated to the left in patients with situs inversus totalis, which supported that the curve direction and vertebrae rotation were mainly determined by organs distribution.…”

“…14 Male Unknown Situs inversus totalis Zhu et al, 2017 [1] 9 Female Hemivertebrae Situs inversus totalis, syringomyelia, congenital heart defect, pulmonary dysfunction, hydronephrosis Alkin et al, 2018 22 Female Unknown KS Guo et al, 2022 [9] 19 Male Idiopathic scoliosis KS, smell and hearing defects, Asthenoteratozoospermia Guo et al, 2022 [9] 37 Female Idiopathic scoliosis KS, smell and hearing defects, immature uterus Our case, 2022 2 Female Hemivertebrae Situs inversus totalis, atrial septal defect, polydactyl KS = Kartagener syndrome.…”

Homozygous mutation in DNAAF4 causes primary ciliary dyskinesia in a Chinese family

“…The mechanism of different pathogenic genes leading to different clinical phenotypes, or even different mutations of the same pathogenic gene leading to different clinical phenotypes (Shoemark et al, 2018) is still unclear, which requires more basic research to explore. Patients with known DNAAF4 mutations tend to exhibit severe phenotypes (Tarkar et al, 2013;Guo T et al, 2022), including neonatal respiratory distress, recurrent respiratory symptoms, and infertility. In this study, the proband did not manifest neonatal respiratory distress, but exhibited complete situs inversus, chronic sinusitis, bronchiectasis, recurrent bronchitis and pneumonia, and infertility, with low level of nNO and severe pulmonary ventilation dysfunction.…”

“…But absolute infertility is occurred in female with mutations in the genes DNAAF1 and LRRC6 encoding dynein axonemal assembly factor ( Vanaken et al, 2017 ). Previous studies and reports have suggested that mutations in DNAAF4 can lead to infertility (male and female) ( Tarkar et al, 2013 ; Guo T et al, 2022 ). Therefore, we can infer that the DNAAF4 mutation caused infertility in the proband.…”

“…Patients with known DNAAF4 mutations tend to exhibit severe phenotypes ( Tarkar et al, 2013 ; Guo T et al, 2022 ), including neonatal respiratory distress, recurrent respiratory symptoms, and infertility. In this study, the proband did not manifest neonatal respiratory distress, but exhibited complete situs inversus, chronic sinusitis, bronchiectasis, recurrent bronchitis and pneumonia, and infertility, with low level of nNO and severe pulmonary ventilation dysfunction.…”