Which defect in adhesion and chemotaxis is responsible for developmental delay, microcephaly, and short stature?

The condition associated with developmental delay, microcephaly, and short stature is linked to LAD 2, also known as leukocyte adhesion deficiency type 2. This specific defect pertains to the inability of leukocytes to adhere to the endothelium and migrate to sites of infection or inflammation due to a lack of sialylated Lewis x antigen on the surface of leukocytes. This specific antigen is crucial for the rolling and subsequent adhesion of leukocytes to blood vessel walls, a critical step in the inflammatory response.

In individuals with LAD 2, the functional deficit in chemotaxis and adhesion results in severe recurrent infections, as the immune system cannot effectively recruit leukocytes to the site of infection. Moreover, the systemic effects of this immunodeficiency can manifest in diverse ways, including developmental delays due to chronic infections and inflammatory responses that can influence growth patterns, resulting in short stature and microcephaly due to either nutritional impairments from recurrent infections or direct impacts on neurodevelopment.

The other types of leukocyte adhesion deficiency, such as LAD 1, LAD 3, and LAD 4, have distinct genetic and clinical features that do not typically present with the combination of developmental delay, microcephaly, and short stature in the