Clinical experience with single-nucleotide polymorphism-based non-invasive prenatal screening for 22q11.2 deletion syndrome.

OBJECTIVES: To evaluate the performance of a single-nucleotide polymorphism (SNP)-based non-invasive prenatal test (NIPT) for the detection of fetal 22q11.2 deletion syndrome in clinical practice, assess clinical follow-up and review patient choices for women with high-risk results. METHODS: In this study, 21 948 samples were submitted for screening for 22q11.2 deletion syndrome using a SNP-based NIPT and subsequently evaluated. Follow-up was conducted for all cases with a high-risk result. RESULTS: Ninety-five cases were reported as high risk for fetal 22q11.2 deletion. Diagnostic testing results were available for 61 (64.2%) cases, which confirmed 11 (18.0%) true positives and identified 50 (82.0%) false positives, resulting in a positive predictive value (PPV) of 18.0%. Information regarding invasive testing was available for 84 (88.4%) high-risk cases: 57.1% (48/84) had invasive testing and 42.9% (36/84) did not. Ultrasound anomalies were present in 81.8% of true-positive and 18.0% of false-positive cases. Two additional cases were high risk for a maternal 22q11.2 deletion; one was confirmed by diagnostic testing and one had a positive family history. There were three pregnancy terminations related to screening results of 22q11.2 deletion, two of which were confirmed as true positive by invasive testing. CONCLUSIONS: Clinical experience with this SNP-based non-invasive screening test for 22q11.2 deletion syndrome indicates that these deletions have a frequency of approximately 1 in 1000 in the referral population with most identifiable through this test. Use of this screening method requires the availability of counseling and other management resources for high-risk pregnancies.

ACMG statement on noninvasive prenatal screening for fetal aneuploidy.

Noninvasive assessment of the fetal genome is now possible using next-generation sequencing technologies. The isolation of fetal DNA fragments from maternal circulation in sufficient quantity and sizes, together with proprietary bioinformatics tools, now allows patients the option of noninvasive fetal aneuploidy screening. However, obstetric care providers must become familiar with the advantages and disadvantages of the utilization of this approach as analysis of cell-free fetal DNA moves into clinical practice. Once informed, clinicians can provide efficient pretest and posttest counseling with the goal of avoiding patient harm. It is in the public's best interest that test results contain key elements and that laboratories adhere to established quality control and proficiency testing standards. The analysis of cell-free fetal DNA in maternal circulation for fetal aneuploidy screening is likely the first of major steps toward the eventual application of whole fetal genome/whole fetal exome sequencing.

Relationship between salivary IgA secretion and upper respiratory tract infection following a 160-km race.

AIM: The relationship between salivary IgA secretion rate and upper respiratory tract infection (URTI) was studied in 155 ultramarathoners (126 males, 29 females, mean age 46.5+/-0.7 y) who had qualified to run the 160-km 2003 Western States Endurance Run. METHODS: Subjects provided saliva samples during registration, held the morning before the race, and within 5-10 minutes postrace (mean race time, 26.2+/-0.3 h). Unstimulated saliva was collected by expectoration for 4 minutes into 15-mL plastic, sterilized vials. Runners finishing the race and providing pre- and postrace saliva samples (n=106) turned in a health log specifying URTI episodes and severity of symptoms for the 2-week period following the race. RESULTS: The total volume of saliva that the runners was able to expectorate during sample collection decreased 51% postrace compared to prerace values (P<0.001). Saliva protein concentration increased 20% (P<0.001) while the saliva protein IgA concentration decreased 10% (P<0.05). Salivary IgA secretion rate decreased 46% when comparing pre- to postrace values (P<0.001). Twenty-four percent of the runners finishing the race and providing salivary samples reported an URTI episode lasting 2 days or longer during the 2-week period following the race (mean number of days with symptoms was 5.4+/-0.6 days). The decrease in salivary IgA secretion rate (pre- to postrace) was 53% greater in the 25 runners reporting URTI (-355+/-45 microg/min) compared to the 81 runners not reporting URTI (-232+/-37 microg/min), (P=0.04). CONCLUSIONS: In summary, nearly 1 in 4 runners reported an URTI episode during the 2-week period following a 160-km race, and the decrease in salivary IgA secretion rate was significantly greater in these runners compared to those not reporting URTI.

Evaluation of azoestriol antisera for estriol measurements in pregnancy plasma directly and after extraction.

2-(4'-carboxyphenylazo)-estriol antisera were employed to quantitate pregnancy plasma estriol in ether extracts by single phase radioimmune assay without chromatography. Utilizing antiserum which crossreacted minimally even with the monoglucosiduronate metabolites, unextracted plasma estriol measurements were identical statistically to ether extract determinations.

Adrenal steroidogenesis in very low birth weight preterm infants.

Adrenal steroidogenesis was evaluated in 25 sick premature infants with a gestational age of less than 30 weeks. ACTH stimulation tests were performed on the fourth day of life using synthetic ACTH (36 micrograms/kg). Considering the stress and degree of illness, preterm newborns had low basal cortisol levels (mean +/- SEM, 207.4 +/- 23.5 nmol/L), and their levels were similar to basal levels reported for healthy full-term newborns (170.7 +/- 26.8 nmol/L; P = 0.31; reference data from Endocrine Sciences, Inc., Calabasas Hills, CA). However, compared to term neonates, preterm infants had markedly elevated basal levels of 17-hydroxypregnenolone (54.3 +/- 11.2 nmol/L), 17-hydroxyprogesterone (19.7 +/- 4.0 nmol/L), and 11-deoxycortisol (19.1 +/- 3.3 nmol/L), which were 7-, 18-, and 8-fold higher, respectively, than values for term infants. The activity of 3 beta-hydroxysteroid dehydrogenase was not significantly reduced in extremely premature neonates (mean basal ratio of 17-hydroxypregnenolone/17-hydroxyprogesterone, 2.9 +/- 0.2; ACTH-stimulated ratio, 6.5 +/- 0.4). In contrast, the mean basal substrate/product ratio of 11-deoxycortisol was markedly elevated in the preterm infants (11.9 +/- 2.2, ratio x 10(-2) compared to that in the full-term infants (2.1 +/- 0.4, ratio x 10(-2); P < 0.001). These findings are consistent with decreased activity of 11 beta-hydroxylase (11 beta OH) in preterm infants born at less than 30 weeks gestation. Decreased 11 beta OH activity appears to be more prominent than the deficiency of 3 beta-hydroxysteroid dehydrogenase that has been found in infants with lesser degrees of prematurity, suggesting that 11 beta OH activity may be regulated during fetal development to increase during the latter part of gestation.

Vitamin E and neonatal bilirubinemia.

A study was designed to determine the effect of vitamin E on bilirubinemia in the preterm infant. Twenty infants with birth weight between 1,000 and 1,500 gm and 20 infants with birth weights between 1,501 and 2,000 gm were studied. Half the infants in each birth weight group received vitamin E administered intramuscularly in a total dose of 50 mg/kg during days 1 to 3 of life; the remaining infants served as controls. The administration of vitamin E produced significantly increased plasma tocopherol concentrations and normal hydrogen peroxide hemolysis tests by the end of the first week of life. Infants with birthweights less than or equal to 1500 gm who received vitamin E demonstrated a significant decrease in serum bilirubin on day 3 of life (6.5 +/- 2.2 vs 8.8 +/- 2.2 mg/dl) as well as a significant decrease in peak serum bilirubin during the first week of life (8.3 +/- 2.2 vs 10.6 +/- 2.6 mg/dl). The duration of phototherapy also was significantly less in the vitamin E-supplemented group (48 +/- 18 vs 107 +/- 31 hours). These differences were less pronounced in infants with birth weights more than 1,500 gm.

Composition of breast milk from mothers of preterm infants.

The influence of daily mechanical expression of breast milk on nutritional composition was examined by comparing expressed milk from 12 mothers who delivered preterm with milk from two groups of mothers delivering at term: nine mothers who mechanically expressed all milk and five mothers who nursed their infants at the breast. Collections were obtained at four-hour intervals over a period of 24 hours so that variability of constituents in milk of different mothers, as well as variability in the same mother over a 24-hour period, could be assessed. Preterm milk contained significantly higher concentrations of protein, sodium, and chloride, and lower concentrations of of lactose than the milk from either group of mothers delivering at term. The mean concentrations of protein, sodium, chloride, and potassium in early preterm milk were adequate to meet the estimated requirements for the preterm infant. However, there was large variability in nutritional composition of milk among mothers and among samples from the same mother.

Rehospitalization for respiratory illness in infants of less than 32 weeks' gestation.

All 133 surviving infants of gestational age less than or equal to 32 weeks born July 1, 1985, to June 30, 1986, as well as a socioeconomically matched full-term control group were observed prospectively for 2 years to determine the incidence of rehospitalization for respiratory illness. Perinatal and seasonal factors associated with increased risk for such hospitalizations were also examined. Forty-seven (36%) preterm infants were rehospitalized compared with 3 (2.5%) of 121 term infants (P less than .001). Preterm infants with and without rehospitalization were similar for mean birth weight (1104 +/- 329 g and 1188 +/- 360 g, respectively) and gestational age (28 +/- 2 weeks for both groups); however, infants who were subsequently rehospitalized had required more days of mechanical ventilation, supplemental oxygen therapy, and neonatal intensive care. While a history of bronchopulmonary dysplasia was a risk factor for rehospitalization (45% compared with 25% of those without bronchopulmonary dysplasia, P less than .05), preterm infants with no history of bronchopulmonary dysplasia still showed a 10-fold increase compared with control infants. Among the 43 infants who required no mechanical ventilation beyond the day of birth, 10 (23%) required rehospitalization.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperbilirubinemia in infants of diabetic mothers.

Large for gestational age (LGA) infants of insulin-dependent diabetic mothers (IDM), appropriate for gestational age (AGA) IDM, and infants of nondiabetic mothers were compared for the incidence of neonatal hyperbilirubinemia and related etiologic factors. At 60 hours of age, LGA IDM had significantly higher serum bilirubin concentrations (12.3 +/- 2.1 mg/100 ml) than AGA IDM (7.6 +/- 3.9 mg/100 ml) or control infants (7.8 +/- 2.8 mg/100 ml) (P < .001). Peak serum bilirubin concentrations were also significantly higher in LGA IDM (14.4 +/- 2.1 mg/100 ml) than in AGA IDM (8.4 +/- 3.7 mg/100ml) or control infants (8.6 +/- 3.3 mg/100 ml) (P < .001). Mean percent of carboxyhemoglobin was used as an indicator of hemolysis and showed a significant elevation in LGA IDM (1.51 +/- 0.19) when compared to AGA IDM (1.10 +/- 0.27) and control infants (1.19 +/- 0.33) (P < .05). No significant differences were found among the three groups with respect to mode of delivery, frequency of pitocin administration, 5-minute Apgar scores, incidence of isoimmunization, incidence of enclosed hemorrhage, hemoglobin concentration, bilirubin concentrations at 12 hours, and percent of weight loss. Our data suggest that only LGA IDM are at increased risk for hyperbilirubinemia and that increased heme turnover is a significant factor in the pathogenesis.

Vitamin E and neonatal hemolysis.

A study was designed to determine if the presence of vitamin E deficiency during the first week of life played a contributory role in the shortened red cell life span observed in the premature infant. Carboxyhemoglobin values were used as an index of hemolysis. Ten infants received vitamin E administered intramuscularly in a total dose of 125 mg/kg during days 3 to 7 of life; ten infants served as controls. The mean percent carboxyhemoglobin level fell significantly from day 3 to day 8 in the treated group (1.08% to 0.78%) whereas the mean value remained unchanged at 0.96% in the control group. The administration of vitamin E appears to reduce but not eliminate the accelerated red cell destruction that characterizes the preterm infant. Pediatrics, 59:995-997, 1677, VITAMIN E, HEMOLYSIS, PREMATURE INFANT, CARBOXYHEMOGLOBIN.

Impact of a matched term control group on interpretation of developmental performance in preterm infants.

One hundred twenty-four children who were born at 24 to 31 weeks' gestation and 124 term children matched in social background underwent serial developmental evaluations. The Bayley Mental Developmental Index at 6, 15, and 24 months and the McCarthy General Cognitive Index at 4 years were used to classify cognitive outcome for preterm children as normal (indices higher than 1 SD below the mean), mild-moderately delayed (indices between 1 and 2 SD below the mean), or severely delayed (indices > or = 2 SD below the mean). Classifications based on norms derived from the performance of the term control group were compared with those based on published standardized test scores. The control group had substantially higher mean (+/- SD) Bayley Mental Developmental Indices at 6 (111 +/- 11), 15 (114 +/- 13), and 24 months (115 +/- 21) than the published test mean (100 +/- 16). Consequently, significantly more preterm children were classified as normal when the Bayley test mean was used than when the performance of the control group was used to define the normal range (84% vs 52% at 6 months, 82% vs 49% at 15 months, and 70% vs 47% at 24 months). Severe cognitive delays were infrequent when defined by test mean (6% to 11%) but two to three times greater when the control group scores were used. In contrast, the control group had a mean McCarthy General Cognitive Index at 4 years (102 +/- 14) that was similar to the published test mean (100 +/- 16).(ABSTRACT TRUNCATED AT 250 WORDS)

Creatine kinase brain isoenzyme: relationship of cerebrospinal fluid concentration to the neurologic condition of newborns and cellular localization in the human brain.

Immunocytochemical study of human brain showed creatine kinase brain isoenzyme (CKBB) present in both neurons and astrocytes. Because creatine kinase brain isoenzyme is an intracellular enzyme that might be released with brain injury, its concentration in the CSF of newborns was measured using a radioimmunoassay. Infants who suffered a documented neurologic insult (a cerebroventricular hemorrhage or a CNS infection) were found to have a greater mean CSF creatine kinase brain isoenzyme concentration than those without a history of neurologic insult. Infants with a high concentration had a poor short-term outcome (death or neurologic abnormality when discharged) more frequently than did those with a lower concentration. Infants with a grade 3 or 4 cerebroventricular hemorrhage had a higher mean concentration than did those with a grade 1 or 2 hemorrhage. These data are consistent with the hypothesis that CSF creatine kinase brain isoenzyme is a metabolic indicator of brain damage in newborns.

Pedigree analysis of aryl hydrocarbon hydroxylase inducibility in acute leukemia of childhood.

We determined lymphocyte aryl hydrocarbon hydroxylase (AHH) inducibility for members of 13 families with one or more children with acute lymphoblastic leukemia (ALL) and 12 control families. Pedigree analysis suggested that aromatic hydrocarbon responsiveness (i.e. inducibility) is a codominant trait. Heterozygotes were found to be moderately responsive with IR values intermediate between homozygous minimally responsive and homozygous highly responsive individuals. Homozygous recessive and heterozygous genotypes accounted for 54% and 36% of ALL children respectively. The risk of ALL among minimally aromatic hydrocarbon responsive children was twice that of highly responsive children.

The second-trimester fetus with isolated choroid plexus cysts: a meta-analysis of risk of trisomies 18 and 21.

OBJECTIVE: To assess the risk of trisomy 18 and trisomy 21 associated with isolated choroid plexus cysts diagnosed by ultrasound in the second trimester. METHODS OF STUDY SELECTION: We reviewed the unabridged PREMEDLINE and MEDLINE databases for articles written in the English language regarding second-trimester fetal isolated choroid plexus cysts and trisomies 18 and 21, published in the period 1987-1997. Selection criteria included only second-trimester, prospective studies in which the rate of fetal isolated choroid plexus cysts could be calculated, the number of fetuses with trisomy 18 and 21 was reported clearly, and pregnant women of all ages were included, rather than only those at high risk for aneuploidy due to advanced maternal age. TABULATION AND RESULTS: Thirteen prospective studies, comprising 246,545 second-trimester scans, were selected. Among 1346 fetuses with isolated choroid plexus cysts, seven had trisomy 18, and five had trisomy 21. For each study, a 2 x 2 table was constructed and the likelihood ratio of a positive test was computed. The likelihood ratios for trisomies 18 and 21 were found to be homogeneous (P = .08 for trisomy 18, and P = .16 for trisomy 21). The summary likelihood ratio and 95% confidence interval (CI) for each chromosomal abnormality were calculated using the Mantel-Haenszel fixed effects model of meta-analysis. The summary likelihood ratio for trisomy 18 was 13.8 (CI 7.72, 25.14, P < .001) and for trisomy 21 was 1.87 (CI 0.78, 4.46, P = .16). CONCLUSION: The likelihood of trisomy 18 was 13.8 times greater than the a priori risk in fetuses with isolated choroid plexus cysts diagnosed in the second trimester. However, the likelihood of trisomy 21 was not significantly greater than the a priori risk with isolated choroid plexus cysts. The data supported offering pregnant women karyotyping to rule out trisomy 18 when maternal age at delivery is 36 years or older, or when the risk for trisomy 18 detected by serum multiple-marker screen is more than one in 3000.

Pregnancy hormone concentrations in marijuana users.

The maternal serum concentrations of human chorionic gonadotropin, pregnancy-specific beta-l-glycoprotein, placental lactogen, progesterone, 17-hydroxyprogesterone, estradiol and estriol were measured in 13 women who smoked marijuana regularly throughout pregnancy. Cannabinoid use in these women was confirmed by RIA measurements of their serum delta 9-tetrahydrocannabinol (THC) concentrations. These THC using women were matched within 2 1/2 weeks of gestational age with 13 pregnant non-THC using controls drawn from the same population. Placental protein and steroid hormone concentrations were within established normal ranges for gestational age and there were no significant differences between the groups in the concentrations of any of the protein and steroids measured. In addition, no significant differences between THC users were found following linear regression analysis of placental hormone concentrations as a function of gestational age. Thus, this study suggests that marijuana use during pregnancy does not significantly alter the circulating maternal concentrations of trophoblastic protein hormones or major fetoplacental steroid hormones.

In vivo confocal microscopic analysis of corneal allograft rejection in rabbits.

PURPOSE: To demonstrate in vivo confocal microscopic features of corneal allograft rejection that may be useful for differentiating graft rejection from other conditions. METHODS: Corneal donor buttons from Dutch Belted (DB) pigmented rabbits were transplanted orthotopically into New Zealand White (NZW) recipient corneal beds. Slit-lamp and confocal microscopic examinations were performed every 3 days thereafter until the time of graft failure. RESULTS: Allograft-rejection signs began to appear during the fourth postoperative week. In epithelial rejection, small inflammatory cells were visualized forming a linear rejection line mixed with larger damaged epithelial cells. Subepithelial infiltrates (SEIs) could be discerned as aggregates of small and highly refractile inflammatory cells within the extracellular matrix. An area of stromal rejection showed increased reflectivity of stromal edema with numerous small infiltrated inflammatory cells. Keratic precipitate (KP) was visualized to be protruding into the anterior chamber with surrounding normal polygonal endothelial cells at its base. Endothelial rejection lines were formed by cellular aggregates of small inflammatory cells and damaged larger endothelial cells with pyknotic highly reflective nuclei. With the progression of endothelial rejection, damaged endothelial cells decreased in number, increased in size, and extended pseudopod-like cytoplasmic structures. CONCLUSION: In vivo confocal microscopy can provide us with detailed histopathology of corneal graft rejection, which might be useful for differentiating immune rejection from other graft conditions and may provide a technique for early diagnosis of rejection before slit-lamp findings.

Screening for the aneuploid fetus.

Advances in ultrasound technology have dramatically improved the detection of fetal defects. Although only an invasive test can provide a diagnosis, the incorporation of sonography into current biochemically based screening programs should significantly improve the detection of a host of other physically based fetal abnormalities. This article provides an overview and discussion of the prenatal sonographic features that may suggest the presence of a significant chromosomal abnormality.

Craniofacial and neck anomalies.

The evaluation of the craniofacial region is a multistep process. First, sonographic skill and expertise are required to ascertain these often subtle abnormalities. Next, precise measurements must be obtained in appropriate and reproducible planes. Finally, a thorough search for other related fetal anomalies is essential. Exciting breakthroughs in our understanding of underlying courses and mechanisms can now guide the practitioner not only in deciding whether or not to pursue invasive testing, but which tests to order, particularly if molecular diagnosis may be required. Complementary advances in ultrasound technology, prenatal diagnosis, and genetic research will have the potential to enhance the accuracy of our counseling, management, and overall care of our patients.

Feeding the low birth weight infant.

A true gold standard for assessing the nutritional outcome of preterm infants remains elusive. We are seeing an expansion beyond the traditional intrauterine-based short-term growth and nutrient retention rates toward a broader, and possibly life-long, range of outcomes. As our nutritional end points shift, the suitability of the preterm infants' own mothers' milk may become more apparent. Whether the unique properties of human milk or the use of human milk components for fortification are sufficient to rekindle the use of donor milk from milk banks remains to be seen. Improved formulas designed specifically for preterm infants and the possibility of providing passive immunity in formula have added fuel to the debate over what constitutes an ideal nutrient source. The optimal time to begin to feed our smallest and sickest patients is being reevaluated. A policy of exclusive parenteral nutrition for prolonged periods of time may be replaced with one in which minimal amounts of feeding are used, in conjunction with parenteral support, to prepare and maintain intestinal function until advancements toward full enteral nutrition are possible. Although well-controlled trials are needed to add substance to our decisions on many feeding methods, such as intermittent bolus versus continuous gastric infusion, the use of transpyloric feeding should be discouraged. Finally, we need to determine if there are any tangible nutritional benefits from the use of nonnutritive sucking. It is hoped that resolution of some of the controversies of feeding preterm infants will broaden our clinical view of infant nutrition. The discussion on work rounds will then move away from the current "did the baby get 120 kcal/kg yesterday?" toward an informed discussion of how, what, when, and why to feed the infant. Over a century ago, Abraham Jacopi cautioned pediatricians that "You cannot feed a baby with mathematics; you must feed them with brains."