Cartilage-hair hypoplasia syndrome: increased apoptosis of T lymphocytes is associated with altered expression of Fas (CD95), FasL (CD95L), IAP, Bax, and Bcl2.

Cartilage-hair hypoplasia (CHH) is a rare autosomal recessive short-limbed dwarfism associated with thin and sparse hair and cell mediated or combined immunodeficiency. However, the basis of immune deficiency in CHH is unclear. In this study, we investigated a role of apoptosis in immunodeficiency in a patient with CHH. An increased apoptosis of both CD4+ and CD8+ T cells, as determined by TUNEL assay, was observed in CHH compared to an age-matched healthy dwarf control. Increased apoptosis in CHH was associated with increased expression of Fas (CD95), CD95L, and Bax and decreased expression of Bcl-2 and inhibitor of apoptosis protein (IAP) compared to the control. These data suggest that lymphopenia and immunodeficiency in CHH may be, at least in part, due to increased apoptosis of T cells, possibly through the Fas/ FasL signaling pathway.