PP130. MUTATION ANALYSIS OF THE BTK GENE IN PATIENTS WITH X-LINKED AGAMMAGLOBULINEMIA IN MACEDONIA S. PEOVA, K. Mironska, L. Kareva, K. Stavric
University Children’s hospital, Department of immunology, Clinical Centre Skopje, Macedonia;
*Corresponding Author: page: 106
X-linked (Bruton's) agammaglobulinemia (XLA) is a primary immunodeficiency caused by a block in B-cell development caused by mutations in the Bruton's tyrosine kinase (BTK) gene.
A retrospective clinical and immunological survey in 6 male childrenclinically diagnosed as XLA on the basisof hypo- or agammaglobulinemia . Molecular diagnosis is done in referent center in 4patients. The results of mutation analysis of the BTK gene performed at the DNA level are following: 1) two brothers : Tryptophan mutations 634 Stop – Guanine 2033 Adenine with polymorphism in exon 18 Cysteine 633 Cysteine – Thymine 2031 Cytosine 2) one case: insertion of a cytosine in a stretch of cytosines, 3) one case: Aspartic acid 579 Asparagines mutation. Patients' ages is from to 23 years.Mean age at diagnosis and mean duration of follow-up were 3.5 and 7,5 years respectively. 2 are sporadic and 2 familial cases. Respiratory infections were the most frequent manifestation both prior to diagnosis and over follow-up ( otitis, chronic sinusitis, bronchopneumonia ).Patients were evaluated by respiratory function tests and computed tomography and2 had chronic lung disease. Other infections developed, including enteral infections with Giardia- Lamblia (3) and aseptic arthritis (2). In 4 patients puberty was normal. Since 1996 all were on intravenous immunoglobulin (IVIg) substitution therapy(0.40 g/kg every 3 weeks), mean individual residual IgG levels ranged500 - 1140 mg/dL (median, 700 mg/dL. During IVIg replacement, the incidence of bacterial infections requiring hospitalization fell.
XLA is a heterogeneous disease and many aspects of XLA and BTK function remain unresolved. Atypical presentations have been reported, and no clear genotype-phenotype correlation has been established. The identification of the Btk gene defect allows unambiguousassignment of a molecular diagnosis to individuals with XLAand to female carriers. Screeningof individuals with atypical or less severe XLA phenotypes,including those previously labelled as common variable immunodeficiencyor immunoglobulin subclass deficiency, has shown that some ofthese individuals may also have Btk defects.