Molecular diagnosis of velo-cardio-facial syndrome among sri lankan patients with congenital cardiac defects

Abstract

Velo cardio facial Syndrome (VCFS) is caused by a 3 Mb deletion of chromosome 22qll.2. Its multiple clinical features include orofacial clefting, congenital cardiac defects (especially conotruncal),developmental delay and learning difficulties. Hypoparathyroidism and thymic hypoplasia are associated. Dysmorphic features include expressionless face, prominent nose, narrow eyes and long fingers/ toes. Clinical diagnosis is difficult due to its variability making molecular diagnosis essential but this is often too expensive for widespread use. We have developed a less expensive semi-quantitative PCR method for diagnosing VCFS and report preliminary results in congenital cardiac defect patients.OBJECTIVE: • Identify the 22qll.2 deletion syndrome among a selected group of children with typical cardiac defects • Describe clinical features of affected cases DESIGN, SETTING AND METHOD: TweIve children (6 males, mean age 3y lmo) with conotruncal congenital cardiac anomalies or cardiac defects associated with other clinical feature of VCFS were .recruited following informed consent from parents. Ethical approval had been granted for this study. A blood sample was obtained for DNA extraction and the clinical data recorded. Molecular diagnosis was performed using semi-quantitative PCR. RESULTS: Three cases were positive for the deletion. Their cardiac anomalies were an interrupted aortic arch,tetralogy of Fallot and right sided aortic arch. None had palatal anomalies and two (67%) had learning difficulties. None had a positive family history. Only one had facies that were typical. The negative cases included six with aortic arch anomalies, none with clefting and 4 with learning difficulties(44). Two had a family history suggestive of VCFS and two had typical facial features. CONCLUSIONS: Three out of the 12 children were positive for the 22qll.2 deletion.