Absent or hypoplastic thymus on ultrasound: a marker for deletion 22q11.2 in fetal XXXX .

@entity3894 @entity215 @entity1757 @entity60942 @entity509 @entity338 @entity6732 @entity299 @entity1146 @entity10515 @entity2418 @entity4297
OBJECTIVE: @entity4297 ( @entity4297 ), particularly @entity2418 , may be associated with deletion of chromosome 22q11.2. @entity10515 or @entity509 is known to be a typical feature in this condition. We aimed to establish (i) the prevalence of @entity60942 in fetal @entity4297 and (ii) whether ultrasound assessment of an absent or hypoplastic fetal thymus helps in preselection of a group who are at high risk for this deletion. STUDY DESIGN: In fetuses (> 16 weeks) with @entity4297 , karyotyping and fluorescence in situ hybridization for 22q11.2 were offered and the fetal thymus was evaluated sonographically. RESULTS: One hundred and forty-nine fetuses with @entity4297 and normal karyotype were analyzed. Seventy-six fetuses had @entity2418 . 22q11.2 deletion was present in 10 cases (6.7%), all of which had @entity2418 (13.1%). @entity6732 or absence was suspected in 11 cases with @entity2418 . Nine of these 11 had the deletion; two cases were false positive. One fetus with a normal-sized thymus had deletion of 22q11.2 (sensitivity 90%, specificity 98.5%, positive predictive value 81.8%, and negative predictive value 99.2%). By subtype of @entity299 , there was deletion in four of six fetuses with interruption of the aortic arch, two of four with @entity338 , three of nine with truncus arteriosus and one of 11 cases of @entity215 . @entity1146 with @entity1757 (n = 7), right-sided aortic arch (n = 4), transposition of the great arteries (n = 14), double outlet right ventricle (n = 13) and other complex malpositions of the great vessels (n = 8) were not associated with the deletion. CONCLUSION: @entity6732 or @entity3894 may reliably be diagnosed during fetal echocardiography. The technique allows identification of a group at high risk for 22q11.2 deletion and is more specific and sensitive than by subtype of @entity299 alone.
