CD40LG and severe combined immunodeficiency: However it can reduce the rate of X-linked disorders as in our study the majority of patients were male and this could be due to the presence of PID with X-chromosome inheritance (e.g. X-linked agammaglobulinemia, X-linked hyper IgM and X-linked severe combined immunodeficiency) in which carrier detection is essential in all female siblings and maternal aunts (1, 39).