Heterotaxy: Associated conditions and hospital-based prevalence in newborns

Purpose: To provide insight into the possible etiology and prevalence of he terotaxy, we studied conditions associated with heterotaxy in a consecutive hospital population of newborns. Methods: From 1972 to March, 1999 (except February 16, 1972 to December 31, 1978), 58 cases of heterotaxy were ascer tained from a cohort of 201,084 births in the ongoing Active Malformation S urveillance Program at the Brigham and Women's Hospital. This registry incl udes livebirths, stillbirths, and elective abortions. Prevalence among nont ransfers (i.e., patients whose mothers had planned delivery at this hospita l) was calculated as approximately 1 per 10,000 total births (20 of 201,084 ). Results: We analyzed a total of 58 patients consisting of 20 (34%) nontr ansfers and 38 (66%) transfers. Patients were categorized by spleen status as having asplenia (7 nontransfers, 25 total), polysplenia (8, 20), right s pleen (4, 11), normal left (0, 1), and unknown (1, 0). Among the 20 nontran sfer and 59 total heterotaxy patients, the following associated medical con ditions were present: chromosome abnormality (1 nontransfer, 2 total), susp ected Mendelian or chromosome microdeletion disorder (1 nontransfer, 6 tota l), and maternal insulin-dependent diabetes mellitus (1 nontransfer, 2 tota l). There were 6 twins (1 member each from 6 twin pairs including 1 dizygou s, 4 monozygous, 1 conjoined; 2 were nontransfers). An associated condition occurred in 5 (25%) nontransfer and 16 (28%) total patients, or among 10 o f 53 singleton births (19%). Conclusions: Although most cases of heterotaxy in this series were sporadic events, an associated condition was present i n about one-fourth of the cases. Not all of these conditions would be consi dered causative etiologies. Based on this small series alone, maternal insu lin-dependent diabetes cannot be viewed as a risk factor for heterotaxy. Ho wever, the specific association of diabetes with polysplenia with/without l eft atrial isomerism is noteworthy, and adds weight to animal and epidemiol ogic case-control data.