Question

Peter was born after an uneventful pregnancy and weighed 3.1kg. At 3 months, he developed otitis media and an upper respiratory tract infection. At the ages of 5 months and 11 months, he was admitted to hospital with Haemophilus influenzae pneumonia. The infections responded promptly to the appropriate antibiotics on each occasion. When 16 months old, he developed balanitis. He is the fourth child of unrelated parents: his three sisters show no predisposition to infection.

Examination at the age of 18 months showed a pale, thin child whose height and weight were below the third centile. There were no other abnormal features. He had been fully immunized as an infant (at 2, 3 and 4 months) with tetanus and diphtheria toxoids, whole-cell pertussis, Haemophilus conjugate vaccine and oral polio. In addition he had received measles, mumps and rubella vaccine at 12 months. All immunizations were uneventful.

Immunological investigations (Table C3.1) into the cause of his recurrent infections showed severe panhypogammaglobulinemia with absent antibody production. Although there was no family history of hypogammaglobulinemia, the absence of mature B lymphocytes in his peripheral blood strongly supported a diagnosis of ________________________________?????. His antibody deficiency was treated by 2-weekly intravenous infusions of human normal IgG in a dose of 400mg/kg body weight/month. Over the following 2 years, his health steadily improved: his weight and height are now on the 10th centile, and he has had only one episode of otitis media in the last 18 months.

Table C3.1 Immunological investigations

Quantitative serum immunoglobulins (g/l)
IgG	0.17	[5.5-10.0]
IgA	Not detected	[0.3-0.8]
IgM	0.07	[0.4-1.8]
Antibody activity
Immunization responses
Tetanus toxoid - no detectable IgG antibodies
Diphtheria toxoid - no detectable IgG antibodies
Polio - no IgG antibodies detected
Measles - no IgG antibodies detected
Rubella - no IgG antibodies detected
Isohaemagglutinins (IgM) not detected (blood group A Rh+)
Blood lymphocyte subpopulations (x109/l)

Total lymphocyte count	3.5	[2.5-5.0]
T lymphocytes (CD3)	3.02	[1.5-3.0]
B lymphocytes (CD23)	<0.03	[0.1-0.4]
(CD19)	<0.1	[0.3-1.0]
(CD20)	<0.1	[0.3-1.0]

*Normal range for age 18 months shown in brackets.

Answer 1

DIAGNOSIS IS COMMON VARIABLE IMMUNODEFICIENCY (CVID) SYNDROME

Common Variable Immunodeficiency (CVID) is an antibody deficiency characterised by recurrent and often severe infections primarily affecting the ears, sinuses, and respiratory tract. (sinopulmonary infections).

POINTS IN FAVOUR OF DIAGNOSIS

• Defect in B cell arm of immune system leading to absent B cells
• Hypogammaglobulinemia with low Serum IgG, IgA, and IgM
• Low levels of CD 19 , CD 20
• defective antibody production
• increased susceptibility to recurrent bacterial infections of the sinopulmonary tract , gastrointestinal tract and otitis media.
• Infection can occur at other sites, such as the eyes and skin
• Common infections are encapsulated organisms like streptococcus pneumonia and Haemophilus infuenzae.Other bacterial infections are also common.
• These infections respond to antibiotics but can recur upon discontinuation of antibiotics
• The family members of CVID patients are mostly  normal, suggesting complex inheritance
• With proper antibiotics and gamma globulin, children respond to the treatment .