Submicroscopic deletions at 16p13.3 in Rubinstein-Taybi syndrome: frequency and clinical manifestations in a North American population.

Rubinstein-Taybi syndrome (RTS) is a well delineated multiple congenital anomaly syndrome characterised by mental retardation, broad thumbs and toes, short stature, and specific facial features. The recent localisation of the disorder to 16p13.3 and subsequent identification of a submicroscopic deletion of this region in RTS patients led us to screen a large cohort of affected subjects using the RT1 probe. Among 64 patients with clinical evidence of RTS, seven (11%) had a deletion. Another patient had a translocation of the region without evidence of a deletion. The features of coloboma, growth retardation, naevus flammeus, and hypotonia have a positive predictive value for the presence of an RT1 deletion. Because of the relatively low frequency of deletions in RTS, the RT1 probe is useful in diagnostic confirmation, but has limited use as a screening tool.

Multifetal pregnancy reduction: evaluation of fetal growth in the remaining twins.

OBJECTIVE: Our purpose was to study fetal growth after reduction of high-order multiple gestations to twins. STUDY DESIGN: Birth weight and gestational age data were collected for 236 triplet and greater multiple pregnancies reduced to twins (113 triplets, 89 quadruplets, and 34 quintuplets or above) and was compared with those of a control group of unreduced twins. RESULTS: Rates of intrauterine growth restriction per pregnancy were significantly different between the nonreduced and all categories of reduced multifetal pregnancies. The incidence of intrauterine growth restriction was 19.4% in the nonreduced twins, 36.3% in pregnancies reduced from triplets, 41.6% in pregnancies reduced from quadruplets, and 50% from higher-order multiple gestations. There was a statistically significant trend toward increasing frequency of intrauterine growth restriction with increasing starting fetal number (p = 0.04). The increase in intrauterine growth restriction was primarily accounted for by twin pairs with only one growth-restricted newborn. CONCLUSION: Multifetal pregnancy reduction does not reduce the incidence of intrauterine growth restriction in the remaining fetuses to that of nonreduced twins.

Incidence of bacteremia associated with chorionic villus sampling.

OBJECTIVE: To assess the frequency of transient bacteremia among women undergoing transabdominal and transcervical chorionic villus sampling (CVS). METHODS: One hundred fourteen women undergoing CVS consented to participate in a university review board-approved study protocol. Exclusion criteria included known cardiac valve anomaly or replacement (or other prosthetic) and antibiotic use within the preceding 21 days. Blood cultures (aerobic and anaerobic) were drawn by a single operator on all patients, before CVS and within 15 minutes after completing CVS. Either the catheter tip or needle tip aspirate from each procedure was also sent for culture. RESULTS: Post-procedure bacteremia was detected in two (1.8%) of the patients undergoing CVS. These two patients both had their procedures performed transcervically, resulting in a 4.1% (two of 49) bacteremia rate after transcervical CVS, compared to none (zero of 65) in the transabdominal group (P = .36). The incidence of positive cultures from sampling instruments was also higher in the transcervical group (16.3 versus 0%; P = .003), but did not result in comparable rates of bacteremia among patients with positive instrument cultures. CONCLUSIONS: In this study, CVS was associated with a low rate of bacteremia, regardless of the procedure route. Recommendations for antibiotic prophylaxis in women with abnormal cardiac valves should parallel those for spontaneous vaginal delivery and other comparable genitourinary procedures.

Multifetal reduction of triplets to twins improves perinatal outcome.

OBJECTIVE: Our purpose was to compare the perinatal outcome of triplet pregnancies reduced to twins with the outcomes of continuing triplet pregnancies and twin pregnancies. STUDY DESIGN: Pregnancy outcomes of triplet pregnancies reduced to twins delivered between July 1988 and July 1992 were compared with pregnancy outcomes of continuing triplet and twin pregnancies delivered over the same time period. RESULTS: The mean gestational age at delivery for the reduced triplets was 35.6 weeks, compared with 31.2 weeks in the nonreduced triplets (p = 0.002). The perinatal mortality rate was 30 per 1000 births in the reduction group and 210 per 1000 births in the nonreduced triplets (p < 0.0001). There were no statistically significant differences between the reduced and nonreduced twins. CONCLUSION: Multifetal pregnancy reduction of triplets to twins yields an improved perinatal outcome compared with nonreduced triplets and a similar outcome compared with nonreduced twins.

Selective reduction of multifetal pregnancies.

Selective reduction was carried out in 46 multifetal pregnancies by means of potassium chloride injection into the pericardial region of the fetus. There were three indications for the procedure: to improve perinatal outcome and to increase the likelihood that a term infant would be born in a multifetal pregnancy (34 women); to allow the birth of a healthy infant without the birth of a congenitally abnormal coexisting fetus (8 women); and to preserve a singleton pregnancy when the woman would otherwise have the whole pregnancy terminated (4 women). Of the 80 fetuses left after reduction 75 (94%) have survived. In 3 cases ultrasound scanning showed cardiac activity in the injected fetus 20-30 min after the initial injection despite 2 min of asystole immediately after the injection; repeated injection, carried out the same day, led to fetal death in all 3 cases. Selective reduction of multifetal pregnancies for the three indications described is an ethically justifiable option for the management of multifetal pregnancy, to which there are no public policy obstacles.

Prenatal diagnosis of a large heteromorphic region in a chromosome 5: implications for genetic counseling.

We performed an amniotic fluid chromosome study at 16 weeks of gestation because of advanced maternal age. G-band chromosome analysis demonstrated that one 5q was significantly longer than its homologue. The region subjacent to the centromere appeared similar to a 9qh region. Subsequent Giemsa-11 and C-band staining results of this area were positive. Cytogenetic studies in this family demonstrated several other individuals who have the same chromosome 5qh+ as the proposita. All are asymptomatic. The clinical insignificance of the chromosome heteromorphism in this family readily demonstrates the need for special cytogenetic and family chromosome studies before performing genetic counseling.