Region-of-interest (ROI)-wise analysis further demonstrated that the left Hb had significantly decreased connectivity with the posterior/anterior somatomotor networks (SM-d, SM-v) and posterior dorsal attention network (DAN-<i>p</i>) in CID patients.<h4>Conclusion</h4>Our findings indicate that CID is characterized by asymmetric FC abnormalities of the bilateral Hb, particularly impaired connectivity between the left Hb and SM and DAN networks, without structural changes. Here, GSTM1 is linked to combined immunodeficiency.