Haploinsufficiency of is likely to contribute to developmental delay involving 14q13 microdeletions.

Nucleotide variations or deletions in the NK2 homeobox 1 gene (), located at 14q13.3, lead to symptoms associated with the brain, lungs, and thyroid, and the combination of these phenotypes is clinically recognized as the brain-lung-thyroid syndrome. Many types of nucleotide variants of have been identified, and phenotypic variability has been reported. Chromosomal deletions involving have also been reported; however, phenotypic differences between patients with nucleotide variants of and patients with chromosomal deletions involving have not been well established. Recently, we identified seven patients with 14q13 microdeletions involving the . Most patients exhibited developmental delay. This inquiry arises regarding the potential existence of haploinsufficiency effects beyond those attributed to within the 14q13 microdeletion. However, a literature review has shown that developmental delay is not rare in patients with nucleotide alterations in . Rather, motor function impairment may have affected the total developmental assessment, and the haploinsufficiency of genes contiguous to is unlikely to contribute to developmental delay.