Assessment of Multiplex Ligation-Dependent Probe Amplification (MLPA) as a diagnostic test for Egyptian patients with Williams-Beuren syndrome

Background Williams-Beuren syndrome (WS) is as a rare multisystem genetic syndrome, caused by the hemizygous deletion of approximately 26–28 genes on chromosome 7q11.23. Fluorescence in-situ hybridization (FISH) is considered the gold standard for its diagnosis. However, FISH does not allow the detection of the exact size of the deletion. This study aimed to compare the efficiency and validity of Multiplex Ligation-Dependent Probe Amplification (MLPA) and (FISH) techniques in diagnosing and confirming clinically diagnosed WS. Patients and methods The study comprised twenty-three WS patients they were clinically assessed, cardiovascular evaluation, and laboratory tests, including plasma calcium level, thyroid function tests and glucose tolerance test, were performed. FISH and MLPA analysis were performed for all patients. The MLPA kit (SALSA P029) contained probes for eight genes in the WS critical region: FKBP6, FZD9, TBL2, STX1A, ELN, LIMK1, RFC2, and CYLN2. Results Nineteen patients out of 23 studied cases (82.6%) showed positive deletion of the WS chromosome region (WBSCR) by both FISH and MLPA techniques. One patient (4.3%) showed negative result by FISH while a duplication of the WBSCR was detected by MLPA. Three patients (13.1%) were negative for both FISH and MLPA. In conclusion This is the largest cohort of Egyptian patients with WS, where both FISH and MLPA analysis were used to confirm the diagnosis. MLPA analysis has an advantage over FISH as it is less time consuming and detects smaller, atypical deletions and duplications in the WS.