OBJECTIVETo ascertain 5 short tandem repeat (STR) markers as qualified tools for detecting chromosome 22q11 deletion and to understand the prevalence and clinical importance of the deletions in patients with congenital heart diseases (CHD) from Chinese Han population.

METHODSThe authors selected 5 new tetranucleotide repeat markers, 22D_4_1, 22D_4_2, 22D_4_3, 22D_4_4 and D22S873 located in the proximal region of chromosome 22q11 deletion. One hundred and sixty-three unselected CHD patients and their unaffected parents were analyzed by genotyping of these new tetranucleotide STR markers to detect 22q11 deletion. With fluorescence in situ hybridization (FISH, LSI dual color DNA probe), the deletion status was confirmed in all patients with deletions and some patients without deletions.

RESULTSThe heterozygosity of these STR markers in normal population was more than 0.7, except for 22D_4_1 and 22D_4_2 that were 0.65 and 0.52 respectively. Twelve cases of 163 CHD patients (7.36%) had the deletions at chromosome 22q11. The deletions were confirmed in 9 of 12 patients by FISH, except for 2 cases who had unique nested deletion and 1 case who had nested distal deletion. One hundred and ten patients were associated with ventricular septal defect (VSD); and 9 (8.18%) of these cases had microdeletion. Twenty-one patients were associated with tetralogy of Fallot (TOF); and 3 (14.3%) of these cases had microdeletion.

CONCLUSIONThis study demonstrated that genotyping of 5 STR markers was a useful mean of detecting 22q11 microdeletion in clinical diagnosis owing to its rapid experimental procedure, cost effectiveness and high resolution. 22q11 deletion was common in CHD patients, particularly in VSD and TOF patients, from Chinese Han population.