Trisomy 21 and maternal age of menopause: does reproductive age rather than chronological age influence risk of nondisjunction?

The biological basis underlying the increased risk of nondisjunction in offspring of women of advanced maternal age is not understood. We sought to test the hypothesis that maternal reproductive age (distance in time from approaching menopause) rather than chronological age is pivotal in the etiology of nondisjunction. Our results found no difference in age of menopause between women > or = 30 years old at delivery of a child with trisomy 21 (i.e., age-related nondisjunction) compared to controls. Among women < 30 years of age at delivery of a child with trisomy 21, none underwent premature menopause. Therefore, our findings fail to support the theory that reproductive age plays a major role in the etiology of nondisjunction.

Isolating fetal cells in maternal circulation for prenatal diagnosis

Fetal cells unequivocally exist in and can be isolated from maternal blood. Erythroblasts, trophoblasts, granulocytes and lymphocytes have all been isolated by various density gradient and flow sorting techniques. Chromosomal abnormalities detected on isolated fetal cells include trisomy 21, trisomy 18, Klinefelter syndrome (47,XXY) and 47,XYY. Polymerase chain reaction (PCR) technology has enabled the detection of fetal sex, Mendelian disorders (e.g. beta-globin mutations), HLA polymorphisms, and fetal Rhesus (D) blood type. The fetal cell type that has generated the most success is the nucleated erythrocyte; however, trophoblasts, lymphocytes and granulocytes are also considered to be present in maternal blood. Fetal cells circulate in maternal blood during the first and second trimesters, and their detection is probably not affected by Rh or ABO maternal-fetal incompatibilities. Emphasis is now directed toward determining the most practical and efficacious manner for this technique to be applied to prenatal genetic diagnosis. Only upon completion of clinical evaluations could it be considered appropriate to offer this technology as an alternative to conventional invasive and non-invasive methods of prenatal cytogenetic diagnosis.

Family planning decisions after prenatal detection of fetal abnormalities

OBJECTIVE

Our purpose was to assess the family planning decisions made by women found to be carrying fetuses with chromosome abnormalities or neural tube defects.

STUDY DESIGN

We studied the family planning decisions of 132 women carrying fetuses with chromosome abnormalities (n = 91) or neural tube defects (n = 41) with regard to prenatal diagnosis, pregnancy management decision, patient's gravidity, and maternal and gestational age.

RESULTS

Twenty women (17 carrying fetuses with chromosome abnormalities and 3 with fetal neural tube defects) elected permanent sterilization after completion of the affected pregnancy. Only maternal age and fetal chromosome abnormalities were associated with a decision to obtain permanent sterilization.

CONCLUSIONS

Most women carrying fetuses with chromosome abnormalities or neural tube defects will not choose permanent sterilization after completion of the pregnancy. Delaying such decisions until resolution of grief and depression is now facilitated by the availability of safe, reliable, and relatively long-term reversible contraceptive agents.

Clinical course and outcome of fetuses with isolated cystic nuchal lesions and normal karyotypes detected in the first trimester

OBJECTIVE

We assessed newborn outcome and infant development in cases of first-trimester fetal cystic nuchal lesion and normal karyotype.

STUDY DESIGN

Information regarding newborn outcomes and infant growth and development was prospectively obtained from 32 consecutive pregnancies characterized by fetal cystic nuchal lesions detected in the first trimester (< or = 13.9 weeks' gestation) and normal karyotypes.

RESULTS

Cystic nuchal lesions spontaneously resolved by the twentieth gestational week in 31 cases; all 31 infants had normal results at newborn examination and demonstrated normal growth and development at 12 months of age. Resolution did not occur in one case; prominent hygromas were repaired at birth with normal growth and development through 2 1/2 years of age.

CONCLUSIONS

In most affected fetuses with normal karyotypes, spontaneous resolution will occur with favorable newborn and infant outcomes. However, patients should be counseled that resolution may not occur or that nonchromosome abnormalities may result in a less favorable outcome.

Severity of abnormality influences decision to terminate pregnancies affected with fetal neural tube defects

We examined parental decision concerning pregnancy management in women having fetuses with neural tube defects (NTDs) to determine whether severity of defect or method of detection has an impact on the decision making process. Analysis of decisions by 50 women, whose pregnancies were affected by an isolated neural tube defect (NTD) and characterized by a singleton gestation at 24 gestational weeks or less with normal chromosomal complement (46,XX or 46,XY), were assessed. All 23 women carrying fetuses with anencephaly elected to terminate their pregnancies. Of the 27 women carrying fetuses with spina bifida, 21 (77.8%) elected to terminate their pregnancies and 6 (22.2%) elected to continue their pregnancies. Of the 6 pregnancies that were continued, 4 were initially detected by ultrasonography and 2 were ascertained by maternal serum alpha-fetoprotein screening; defects ranged from 2 to 14 vertebral bodies, and none of the defects were craniad to the T9 level. This is in comparison to 5 of the 21 spina bifida cases that were elective pregnancy terminations, which were characterized by fetal lesions craniad to the T9 level. Severity of NTD thus appears to influence the decision to continue or terminate an affected pregnancy.

Analysis of HLA haplotype segregation in the Schmiedeleut Hutterites of South Dakota

HLA data from 1,085 South Dakotan Schmiedeleut Hutterites were examined for evidence of nonrandom transmission of haplotypes. The inheritance of haplotypes was viewed as a series of genetic contests between competing pairs of parental haplotypes using a maximum likelihood approach first put forward by Carlisle and Woodbury. Haplotype transmission probabilities were expressed in terms of weights, and the null hypothesis that the inheritance pattern was a random stochastic process, equivalent to the equality of the weights, was tested via the likelihood ratio. A total of 1,517 competitions was subjected to analysis, first globally using all data, and then for particular haplotypes of interest. Transmission of haplotype observed to compete with only a single other haplotype was also assessed using an exact procedure. No evidence of preferential transmission of HLA haplotypes was found. These results do not rule out transmission biases that may arise because of selection against homozygotes, mechanisms specifically affecting particular alleles or haplotypes not considered in the present study, or biases arising from maternal-fetal interactions.

Adverse perinatal outcome in patients screen-positive for neural tube defects and fetal Down syndrome

An association between various abnormal mid-trimester maternal serum analyte values and adverse perinatal outcome has been reported. From an original sample of 14,857 women, we observed five women who were 'screen-positive' for both neural tube defects [maternal serum alpha-fetoprotein (MSAFP) > or = 2.5 multiples of the median] and Down syndrome [risk > or = 1/274 using MSAFP, maternal serum unconjugated oestriol (MSuE3), maternal serum human chorionic gonadotropin (MShCG), and maternal age]. The four patients who elected to undergo amniocentesis all demonstrated both normal karyotype and normal amniotic fluid AFP levels. All five cases were associated with intrauterine growth retardation (IUGR) and abnormal pregnancy outcomes. Two cases exhibiting severe IUGR on ultrasound examination were terminated at 19.1 and 21.2 weeks, respectively; the former also exhibited fetal calcifications and positive maternal serology for toxoplasmosis. In another case, fetal demise occurred at 36 weeks' gestation in a patient who had been treated for syphilis in the second trimester. Neither infection was confirmed in fetal tissue studies. Though resulting in live births, the remaining two cases required operative deliveries; emergency Caesarean sections for fetal distress were performed at 38 and 32 weeks, respectively, the latter case being associated with severe pre-eclampsia. We conclude that elevated mid-trimester MSAFP levels concurrent with maternal serum analyte values associated with increased risk for fetal Down syndrome may presage a poor perinatal outcome, particularly IUGR and possibly congenital infection.

Lack of heritability in ovarian germ cell malignancies

OBJECTIVE

Our purpose was to determine whether relatives of patients with ovarian germ cell malignancies not associated with sex chromosome abnormalities are at increased risk for similar tumors.

STUDY DESIGN

We reviewed pedigrees of 78 presumptive 46,XX patients (ages ranging from newborn to 20 years) with malignant ovarian germ cell tumors, excluding cases of dysgerminoma and gonadoblastoma. A three-generation family history of each proband was reviewed specifically to identify cancer in any family member.

RESULTS

Seventy-eight mothers, 87 sisters, 135 aunts, and 156 grandmothers were surveyed. None had a malignant ovarian germ cell neoplasm or other malignant ovarian neoplasm.

CONCLUSION

First- and second-degree relatives of probands with ovarian germ cell malignancies do not have an increased risk for similar tumors. These findings were not predicted because of the well-recognized association of hereditary tumors and early age of onset.

Amniocentesis performed at 14 weeks' gestation or earlier: comparison with first-trimester transabdominal chorionic villus sampling

OBJECTIVE

To compare our initial experiences with early amniocentesis and transabdominal chorionic villus sampling (CVS).

METHODS

We compared the diagnostic and pregnancy outcomes of our initial 250 patients undergoing early amniocentesis (at or before the 14th completed week of gestation) or transabdominal CVS (performed between 9.5-12.9 weeks' gestation). In both groups, the indication for prenatal diagnosis was advanced maternal age (35 years or older at estimated date of delivery).

RESULTS

No diagnostic errors were made using either technique, and the culture failure rate for both methods was 0.8% (two of 250). Seven cytogenetic abnormalities in the early amniocentesis group and seven in the transabdominal CVS group were detected. Nine of the 250 women undergoing early amniocentesis reported spontaneous miscarriages following the procedure, compared to five in the transabdominal CVS group. The loss rates were 3.8% in the early amniocentesis group and 2.1% in the transabdominal CVS group among continuing pregnancies. Frequencies of premature delivery, small for gestational age infants, and associated structural defects in both groups were comparable.

CONCLUSIONS

At this time, early amniocentesis cannot be assumed to be equal to conventional transabdominal CVS or amniocentesis with regard to safety or accuracy; only a large cohort randomized study will adequately determine the safety and efficacy of early amniocentesis.

Molecular analysis to assign parental origin and distinguish de novo i(21q) from t(21q21q) in two Down syndrome fetuses

OBJECTIVE

We sought to determine the origin of two prenatal cases of chromosome 21 rearrangements not amenable to clarification by conventional cytogenetic methodology.

METHODS

Hypervariable repeat polymorphisms (chromosome 21) were used to determine the type of structural rearrangement and the parental origin of the rearranged chromosome. The repeats used were highly polymorphic and located very close to the centromere; thus, the likelihood of differences among the parental alleles and overall informativeness were increased.

RESULTS

The rea(21q21q) chromosomes were identified as a Robertsonian translocation in one fetus and an isochromosome in the other. The extra chromosome material was found to be maternal in origin in both cases.

CONCLUSION

The ability to clarify the origin of abnormal chromosomal rearrangements provides valuable information concerning possible mechanisms of aneuploidy, as well as clinical data that may have an impact in assessing a patient's risk for abnormal offspring.

Significance of septations in isolated fetal cystic hygroma detected in the first trimester

Recent reports have indicated an increased risk for fetal chromosome abnormalities, especially autosomal trisomy, in fetuses with isolated cystic hygroma, or prominent nuchal membranes, detected by ultrasonography during the first trimester. However, these reports present contradictory information regarding the prognostic significance of septations within the cystic hygroma. We evaluated, in blind fashion, 55 consecutive cases of isolated fetal cystic hygroma detected at or before 13.9 weeks' gestation to determine the association between septations and fetal chromosome complement. Septations were associated (P < 0.05) with an increased risk for fetal chromosome abnormalities. However, the incidence of chromosome abnormalities was also increased (12.5 per cent) among cases not characterized by septations. Thus, we believe it prudent to offer invasive prenatal testing to all women found to be carrying fetuses with cystic hygroma, irrespective of the presence or absence of septations.

Ultrasound-guided fetal skin sampling for prenatal diagnosis of genodermatoses

OBJECTIVE

To evaluate the safety and diagnostic efficacy of ultrasound-guided fetal skin sampling for the prenatal diagnosis of genodermatoses.

METHODS

Seventeen pregnancies seen over 6.5 years were analyzed retrospectively. Fifteen were at risk for junctional epidermolysis bullosa and two for recessive dystrophic epidermolysis bullosa. Under ultrasound guidance, a biopsy forceps was inserted through a 14-gauge catheter and directed toward the fetus (thorax, back, or buttocks) to obtain skin samples. The procedures were performed at a mean of 18.3 weeks' gestation (range 16.5-19.5).

RESULTS

Fetal skin sampling was successful in all cases; the mean number of biopsies taken was 3.6 (range two to five). Five of the 17 fetuses were determined to be affected, each with junctional epidermolysis bullosa; these pregnancies were terminated electively and the prenatal diagnoses confirmed. The remaining 12 pregnancies resulted in the delivery of healthy infants at or after 37 weeks' gestation. There were no pregnancy-related complications, specifically preterm rupture of the membranes or preterm labor. Three of the 12 infants had minor skin blemishes believed to be due to the skin sampling.

CONCLUSION

Ultrasound-guided fetal skin sampling is the procedure of choice when fetal skin is required for prenatal diagnosis of genodermatoses.

Positive serum screening for fetal Down syndrome does not predict adverse pregnancy outcome in absence of fetal aneuploidy

OBJECTIVE

The purpose of this study was to determine whether false-positive maternal serum screening for fetal Down syndrome is predictive of poor pregnancy outcome.

METHODS

The pregnancy outcomes of 99 women having positive serum screening for fetal Down syndrome (study group)--based upon maternal serum alpha-fetoprotein (MSAFP), unconjugated estriol (uE3), hCG, and maternal age--were compared to the outcomes of matched control patients having negative serum screening results (control group). The outcome indices analyzed were fetal death, intrauterine growth retardation (IUGR), preeclampsia, and fetal anomalies.

RESULTS

Between the study group and the control group, there were no statistically significant differences in pregnancy outcome with respect to fetal death, IUGR, preeclampsia, or fetal anomalies.

CONCLUSIONS

Our findings demonstrate no apparent increase in the adverse perinatal outcomes analyzed in women having unexplained positive serum screening for fetal Down syndrome. Although further investigation is needed, these results provide no evidence to support increased antepartum surveillance in such patients.

Isolating fetal cells from maternal blood. Advances in prenatal diagnosis through molecular technology

OBJECTIVES

To review the rationale for and progress toward the goal of isolating and analyzing fetal cells circulating in maternal blood, and to explore the feasibility of this method in providing noninvasive prenatal cytogenetic diagnosis.

DATA SOURCES

Critical review of data published since the first report (1969) of fetal metaphases in maternal blood. Emphasis is placed on data since the demonstration by polymerase chain reaction (PCR) in 1989 and 1990 that fetal cells indeed exist in maternal blood.

DATA SYNTHESIS

Clinical evaluations have not yet been conducted, but it is already clear that molecular technologies have allowed the unequivocal demonstration of fetal cells in maternal blood. Using PCR, our own group and others have demonstrated Y sequences and single gene sequences (eg, hemoglobin LeporeBoston) in maternal blood. Thus, fetal DNA sequences indeed exist in maternal blood. Among the various candidate cells, the most promising appear to be fetal nucleated red blood cells. We isolated nucleated red blood cells on the basis of flow-sorting for the transferrin receptor and glycophorin-A. Enriched samples were then subjected to fluorescence in situ hybridization with chromosome-specific probes. This approach allowed us to detect trisomy 21 and trisomy 18, work later confirmed by others.

CONCLUSIONS

Isolating and analyzing fetal cells from maternal blood is clearly possible. Several key biologic questions remain--the optimal cells for isolation, frequency of cells in maternal blood, timing during gestation for maternal blood sampling, and the likelihood of persistence of fetal cells after delivery. Clinical evaluations planned by the National Institute of Child Health and Human Development will determine the sensitivity and specificity of this method and its precise role in prenatal cytogenetic diagnosis.

Prenatal diagnosis of genetic skin disease using fetal skin biopsy samples

BACKGROUND

Understanding normal skin development and identifying markers of genetic skin disease expressed in postnatal skin have permitted the prenatal diagnosis of many severe genodermatoses: bullous diseases, keratinization diseases, pigment cell disorders, and disorders of the epidermal appendages (ectodermal dysplasias). Samples of 16 to 22 weeks' gestation fetal skin obtained by ultrasound-guided biopsy are evaluated using morphologic, immunohistochemical, and biochemical methods.

OBSERVATIONS

The 12-year experience in evaluating samples from fetuses at risk of these disorders has allowed us to establish conditions that must be met before the samples are taken and the criteria for recognizing the disorder, to recommend the site(s) for sampling, and to be mindful of pitfalls that may be encountered in interpreting the tissue structure.

CONCLUSIONS

Fetal skin biopsy is an important diagnostic tool that has permitted families in which members carry the abnormal gene for one of these severe skin diseases to undertake a pregnancy knowing that the condition of the fetus can be determined. Nonetheless, the ultimate goal is phase out this procedure when linkage of more of these disorders to specific genes is understood, specific mutations are characterized, and probes are available for molecular diagnoses using tissue obtained at earlier fetal ages. Until this is possible, fetal skin biopsy remains an important tool that can be used with reasonably high levels of safety and confidence.

Amniocentesis and chorionic villus sampling

Amniocentesis and chorionic villus sampling have been shown through prospective, multicenter trials to be safe and effective methods of prenatal diagnosis; accordingly, a knowledge of these tests is important for those physicians who care for women during their childbearing years. We review the indications, techniques, safety, accuracy, and efficacy of amniocentesis and chorionic villus sampling and compare the advantages and disadvantages of each diagnostic test. This review should enable physicians to provide appropriate counseling and information to women at increased risk for fetal abnormalities detectable by either of these procedures.

The goat as a model for Corynebacterium renale pyelonephritis

Nubian goats were experimentally infected with Corynebacterium renale type II by either the intravenous or intraurethral routes using infection rates of 1.75 x 10(10), 7.08 x 10(19) or 5 x 10(23) organisms. All inoculated goats were anorexic, lost weight and became dull or depressed. Albuminuria, pyuria and epithelial casts were noted in the urine. Following intravenous challenge the animals showed a dose-related elevation of serum ammonia, urea, and creatinine with significant changes in haemoglobin concentration, packed cell volume and leucocyte counts. A mild to severe (sometimes haemorrhagic) cystitis and urethritis and a mild nephrosis were noted post mortem and mucoserous or mucogelatinous non-purulent discharges were present in the renal pelvis. The findings are compared to the naturally occurring C. renale pyelonephritis in cattle and the suitability of the goat as a model for that disease is discussed.

Piriformis abscess mimicking a hip pyarthrosis

Joint sepsis and osteomyelitis often give a confusing clinical picture in children because of the prevalent use of oral antibiotics for otolaryngeal disease, resulting in partially treated musculoskeletal infections. Unusual sites of infection must be considered when the patient does not respond to standard treatment. Recent scanning techniques can be useful in resolving this dilemma.

Deficit of HLA homozygotes in a Caucasian isolate

Deficits of HLA-A, -B homozygotes observed many years ago in two inbred populations suggested negative selection against HLA homozygotes. To determine whether a similar deficiency would be observed in the S-leut Hutterites, a well-characterized Caucasian isolate of European ancestry, and to determine whether selection operated at the allele, locus, or haplotype level, observed and expected numbers of homozygotes were compared in 852 adult Hutterites. Deficits ranging from 11% to 24% were observed for all five loci examined (HLA-A, -B, -C, -DR, and -DQ). However, these deficits were secondary to, and almost completely accounted for by, a 64% loss of individuals homozygous for the haplotype. There was no evidence of deficits affecting only a single allele or locus. The data indicate strong negative selection against HLA homozygotes. This could be due, at least in part, to decreased fecundability among couples sharing HLA-DR. However, these data suggest that additional selective factors acting at the level of the haplotype also operate in this population.