engleski

Microdeletion 22q11 in population at risk

Chromosome 22q11 deletion is the most common microdeletion syndrome with the incidence of 1 per 4000. It causes a spectrum of well-described clinical entities wich include DiGeorge syndrome (DGS), velocardiofacial syndrome (VCFS), conotruncal anomaly face syndrome, Opitz G/BBB syndrome and Cayler cardiofacial syndrome. In addition, 22q11 deletion studies are becoming part of a standardized diagnostic procedures for some isolated defects such as conotruncal cardiac anomalies (CHD) or cleft palate CP. In order to assess the cost effectiveness of such practice it is important to get more information on the actual presence of the 22q microdeletion in an unselected group of individuals presenting with symptomes captured in the acronim CATCH 22 (CHD, Abnormal facies, Thymic hypoplasia, CT and Hypocalcemia). Aim was to determine the frequency of 22q11 deletions in an unselected population of patients presenting with CHD, CP, hypocalcaemia or dysmorphic features suggestive of DGS or VCFS. We performed clinical evaluation, high-resolution chromosome analysis, and FISH using double probe (LSI TUPLE1 localised in 22q11 and LSI ARSA) in 90 children divided into 4 groups (1. congenital heart defects, 2. dysmorphic features, 3. cleft palate, 4. hypocalcemia) according to the first presenting symptom.Genetic analysis confirmed hemizygosity for 22q11 in 7.8 (7/90) patients, three patients presenting with CHD, 2 with hypocalcaemia and 2 with dysmorphic features. After clinical assessment, 5 patients were diagnosed as having DGS, and two as VCSF, therefore we failed to identify a non-syndromic 22q11 deletion. Detecting 22q11 microdeletion by FISH analysis provides a rapid and definitive diagnosis, ensuring appropriate management, genetic counseling and prenatal diagnosis in inherited cases. As patients with a single CATCH 22 feature are not likely to have 22q11 deletion, quick dysmorphological evaluation by the clinical geneticist prior to cytogenetic evaluation can considerably improve diagnostic rate by preselecting individuals at risk.

DiGeorge syndrome; CATCH 22 syndrome; microdeletion 22q

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