Introduction
With an estimated incidence of one in 10,000–20,000 live births worldwide [1], primary ciliary dyskniesia (PCD) is a rare inherited autosomal recessive disease caused by impaired function of motile cilia, resulting in recurrent respiratory inflammation, bronchiectasis, sinusitis, otitis media, and neonatal respiratory distress. Approximately 50% of patients have situs inversus [2,8]. Besides the clinical features, nasal NO concentration, high speed video microscopy analysis (HSVMA) of cilia beat frequency and pattern, ciliary ultrastructure in cross section through transmission electron microscopy (TEM) are all helpful for the diagnosis of PCD[3]. Moreover, genetic testing can help to confirm the diagnosis of PCD. The pathogenic mechanism of PCD is cilia motility dysfunction, which depend on dynein arms composing of the outer dynein arms (ODAs) and the inner dynein arms (IDAs). The gene of dynein axonemal assembly factor 2 (DNAAF2), also known as KTU and PF13, has been reported to encode the cytoplasmic proteins required for the assembly of both ODAs and IDAs, lead to loss of cilia motility and cause PCD[6]. In this paper, we report the clinical manifestations, diagnosis and treatment processes of two siblings with PCD caused by the same compound heterozygous mutations in DNAAF2, one of the mutations is novel.