A clinical case of primary ciliary dyskinesia in a child under one year old with a pathogenic genetic variant of the DNAH5 gene described for the first time

Abstract

Relevance: primary ciliary dyskinesia (PCD) is a rare hereditary autosomal recessive disease from the group of ciliopathies, which is based on a defect in the ultrastructure of the cilia of the epithelium of the respiratory tract and similar structures, leading to a violation of their motor function. It is characterized by the defeat of all parts of the respiratory tract with the formation of a chronic inflammatory process and bronchiectasis. About half of patients with PCD have a complete or incomplete reverse arrangement of internal organs with various variants of heterotaxy (situs inversus). Primary ciliary dyskinesia should be differentiated from cystic fibrosis, primary immunodeficiency conditions, congenital anomalies of the structure of the bronchial tree, bronchiectasis of other origin, bronchial asthma, congenital anomalies of the cardiovascular system. Objective: describe the clinical case of a PCD patient with the first-described pathogenic variant of the nucleotide sequence (chr5:13700862CCATAGA>C) of the DNAH5 gene to familiarize doctors with the clinical features of the disease and modern diagnostic capabilities. Materials and methods: the data from the patient’s medical history, transmission electron microscopy to detect anomalies in the structure of cilia in the biopsy of the nasal mucosa and the results of molecular genetic diagnostics were used. Results. The patient was admitted for 8 months for examination and treatment in June 2022. A child from the 1st pregnancy, the first birth at 43 weeks. From anamnesis: suffered intrauterine pneumonia, otitis media without hearing loss, obstructive bronchitis, episodes of apnea. Neonatal screening for cystic fibrosis is negative. According to the PICADOR scale, 12 points were obtained. On high-speed video microscopy of cilia, there is a violation of the movements of the cilia. On computed tomography of the chest organs, the reverse location of the internal organs was noted, there were no pathological changes in the lungs. The total absence of external and internal dynein handles on transmission electron microscopy was revealed. Exome sequencing revealed the previously described variant of the nucleotide sequence in exon 68 of the DNAH5 gene (chr5:13735348G> A) in a heterozygous state. Also, a previously undescribed variant of the nucleotide sequence (chr5:13700862CCATAGA> C) in a heterozygous state was detected in exon 78 of the DNAH5 gene. Conclusion: modern possibilities of PCD diagnostics are demonstrated by the example of clinical observation. It is noted that patients with suspected PCD need a comprehensive examination. A pathogenic variant of the nucleotide sequence (chr5:13700862CCATAGA>C) of the DNAH5 gene in a heterozygous state has been described for the first time, leading to the deletion of two amino acids without shifting the reading frame (c.13604_13609del p. (Val4535_Tyr4536del); NM_001369.3), which will help for the diagnosis of PCD in the future.