YL Lau

Primary immunodeficiencies (PID) comprises of at least 82 different types and the estimated overall incidence was 1 in 5000 to 10,000 livebirths. Between July 1988 and December 1993, at least 50 cases of PID were diagnosed in Hong Kong, giving an incidence of about 1 in 7,700 livebirths. Since 1994, about 5 to 10 cases of PID were still diagnosed yearly. These cases include X-linked agammaglobulinaemia (n=9), Ig G subclass deficiency (n=6), secretory-Ig A deficiency (n=1), transient hypogammaglobulinaemia of infancy (n=3), common variable immunodeficiency (n=3), ataxia telangiectasia (n= 1), severe combined immunodeficiency (n=3); Wiskott-Aldrich syndrome (n=3), Di George syndrome (n=1), combined immunodeficiency (n=3), chronic mucocutaneous candidiasis (n=1), idiopathic CD-4 lymphocytopenia (n=1), dyskeratosis congenita (n=1), chronic granulomatous disease (n=10), leucocyte deficiency (n=1), chronic neutropenia (n=8), alloimmune neutropenia (n=1), juvenile localized periodontitis (n=1), neutrophil chemotaxis defect (n=1), CGD variant (n=1), congenital asplenia (n=6), natural killer cell deficiency (n=2).

Our treatment programmes included bone marrow transplantation for SCID, WAS and Di George syndrome; regular intravenous immunoglobulin for XLA, CID and ataxia telangiectasia; regular septrin prophylaxis and rescue gamma-interferon for CGD and LAD; rescue granulocyte colony stimulating factor for chronic neutropenia. Patients will be aggressively investigated and treated for any infection. Apart from infections, two patients (one WAS, one AT) developed B-cell lymphoma as a complication of their immunodeficiency. Both were treated successfully and still in complete remission. Children with PID should be diagnosed early and treated accordingly to minimise avoidable complications. Genetic counselling also depends on accurate diagnosis. Gene therapy is being actively pursued for PID.