DNAI2, short for dynein axonemal intermediate chain 2, is a gene encoding a protein that is crucial for the proper function of motile cilia and flagella. It is mainly involved in the cilium movement pathway [1]. Dysfunction in DNAI2 can lead to significant biological consequences, as cilia and flagella play vital roles in various physiological processes.

Mutations in DNAI2 have been found to cause primary ciliary dyskinesia (PCD), a genetically heterogeneous disorder. In four individuals from a family with PCD and outer dynein arm (ODA) defects, homozygous loss-of-function DNAI2 mutations were identified [2]. In five consanguineous families, a founder variant in DNAI2 led to PCD symptoms, with TEM analysis showing lack of ODAs [3]. A novel 6.9 kb microdeletion in DNAI2 was detected in a newborn with PCD, highlighting its role in causing the PCD phenotype [4]. In a medaka PCD mutant, disruption of dnai2 led to LR defects due to disrupted cilia motility in Kupffer's vesicle and severe reduction in outer dynein arms [5].

In conclusion, DNAI2 is essential for the normal function of motile cilia and flagella. Research on DNAI2 mutations and their effects in various genetic models has significantly contributed to our understanding of PCD. These studies have provided insights into the role of DNAI2 in maintaining the structure and function of cilia, which is crucial for normal physiological processes and the prevention of PCD-related diseases.