Final answer:
Agammaglobulinemia (XLA) is the disease that causes a variant in the gene coding for Bruton tyrosine kinase, leading to the arrest of B cell development.
Step-by-step explanation:
The disease that causes a variant in the gene coding for Bruton tyrosine kinase (BTK) and leads to the arrest of B cell development is called agammaglobulinemia (XLA).
Patients with XLA have a defective BTK gene, which encodes the Btk tyrosine kinase. Btk is essential for B-cell maturation and differentiation beyond the pre-B-cell stage, which is required for immunoglobulin production. Without sufficient Btk, B-cell development halts at the pre-B-cell stage, leading to a deficiency in antibody production and recurrent infections.
It's important to note that XLA primarily affects the production of antibodies against extracellular pathogens like Haemophilus influenzae, Streptococcus pneumoniae, S. pyogenes, and S. aureus. Cell-mediated immunity is not impaired in these patients, so they are not particularly vulnerable to infections caused by viruses or intracellular pathogens.