Question

Anthony was a normal, full-term baby at birth. Beginning at about 8 months of age, he suffered from a series of infections such as sinusitis, otitis media, and pneumonia. All of these conditions were successfully treated with antibiotics, but within a few weeks of the resolution of one infection, another would occur. Now at about three years old, Anthony is examined by a pediatrician who notes that he lacks tonsils. After speaking to Anthony’s mother, she reveals that she had a male relative die at infancy from an infectious disease. The pediatrician orders laboratory tests that reveal that the quantity of immunoglobulin in Anthony’s serum is about one-fifth of normal, and that there is a marked deficiency in the number of circulating B-lymphocytes in his blood. However, tests determine that the functional state of Anthony’s T-lymphocytes are all normal. The doctor diagnosis Anthony with a genetic disorder.

1. What genetic disorder does Anthony have?

2. What is the cause of this genetic disorder?

3. Why did Anthony lack tonsils?

4. What treatment(s) will Anthony need and for how long?

5. Explain why Anthony was free of infections in the first 8 months of life.

6. The infections that Anthony had are mostly caused by bacteria. Explain why he was more prone to bacterial infections than viral infections.

Answer 1

1 Antony had X linked Agammaglobulinemia .It is inherited as an x linked disorder.Caused due to mutation in Bruton tyrosine kinase gene.

2 The cause for Anthonys genetic disorder is a mutation in Bruton tyrosine kinase gene. leading to x linked agammaglobulinemia leading to either reduction in lymphoid tissue or total absence of lymphoid tissue's like tonsils adenoids etc and also in this disorder there will be a deficiency of B cells thus resulting in severe reduction in antibody isotopes thus making these individuals susceptible to recurrent bacterial infections in early life followed by a severe life threatening bacterial infections like meningitis ,sepsis ..

3 Anthony lacked tonsils because he had a mutation in the gene Bruton tyrosine kinase which in turn caused X linked agammaglobulinemia,in which there is either a total loss of lymphoid tissue like tonsils etc or decrease in size of the lymphoid tissue like small adenoids etc.Thus Anthony was suffering from X linked agammaglobulinemia whose characteristic feature is the absence or decrease in the size of lymphoid tissue like tonsils and lymph nodes.

4 There is no cure for X linked Agammaglobulinemia but this condition can be treated by Immunoglobulin replacement therapy .It should be done once in a life time and gives cure for life long.Moreover daily dose of oral antibiotics can also help.If total immunoglobulins cannot be replaced then replacement of immunoglobulins on regular basis is also helpful.

Also it should be taken care that no live attenuated vaccines should be administered to such patients with X Linked agammaglobulinemia as these live attenuated vaccines contain weakened form of the pathogen when these are injected into these specific individuals with low immune power will undergo back mutation and regain the virulence capacity of the pathogen and cause the infection.

5 Anthony was free from infections in first 8 months of life because in the first 8 months of his life he is fed breast milk and in breast milk there is IgA antibodies secreted from the breasts of mother.And these IgA antibodies provided passive immunity to the baby in his infancy.

6 The patients with X linked agammaglobulinemia are more susceptible to Bacterial infection rather than viral infections because In viral infections the T lymphocytes are the one that is activated and they have several surface receptors present on their outer surface by which they bind to the virion particles and in turn activates the cytotoxic T cells and these cells are responsible for the lysis of virus.But in case of bacterial infections the B cells are getting activated which in turn release antigen specific antibody and resist the infection by bacteria.

Now in X linked agammaglobulinemia there is a decrease in B cell population of humoral immune system while the T-cell population is not affected thus these individuals with X linked Agammaglobulinemia are more susceptible to bacterial infection rather than viral infections