Mutation of human Lsh, also known as HELLS (Helicase, Lymphoid-Specific), causes an Immunodeficiency, Centromeric Instability and Facial Anomalies (ICF) 4 syndrome which is characterized by recurrent fatal respiratory and gastrointestinal infections associated with hypogammaglobulinemia and immunodeficiency (24, –26). Here, HELLS is linked to immunodeficiency disease.