2006
The same residue is often mutated in the Brutons tyrosine kinase ( Btk ) gene in patients with an X - linked agammaglobulinemia .
 X - linked agammaglobulinemia
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease 
Text: {0} 
Answer:
 X - linked agammaglobulinemia