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Biomedical subjects

M E Norton

Publications and source records attributed to M E Norton.

At least 19 recordsLinked to original sources
PubMed2005

Ethnic variation in the prevalence of echogenic intracardiac foci and the association with Down syndrome.

OBJECTIVE: To determine whether the prevalence of fetal echogenic intracardiac foci (EIF) differs according to maternal ethnicity. METHODS: We performed a retrospective cohort study of all women undergoing second-trimester diagnostic ultrasound examination and amniocentesis at a prenatal diagnosis referral center from January 1 2000 to July 1 2003. Data were collected on the presence of EIF, gestational age at time of ultrasound scan, karyotype results, maternal age and ethnicity. Univariate and multivariate analyses of EIF, ethnicity and presence of aneuploidy were conducted. RESULTS: Among the 7480 women qualifying for the study, EIF were found in 309 (4.1%). When maternal ethnicity was subdivided into Caucasian, African-American, Hispanic, Asian-American, Native American, Asian Indian, and Middle Eastern, the highest rates of EIF were found in fetuses of African-American (6.7%), Asian-American (6.9%), and Middle Eastern (8.1%) mothers compared to a rate of 3.3% in Caucasians (P < 0.001). In all ethnic groups except Hispanics, EIF was associated with an increased risk for Down syndrome (odds ratio range from 1.8 to 15.7). CONCLUSIONS: African-American, Asian-American, and Middle Eastern patients are more likely than patients of other ethnicities to have a fetus with an EIF. Even controlling for ethnicity, fetuses with an EIF still have an increased risk for Down syndrome. As more data accumulate, the prevalence of EIF and its association with Down syndrome among different ethnic groups can be incorporated into patient counseling.

Adult↗
PubMed2001

Prenatal diagnosis and characterization of an unbalanced whole arm translocation resulting in monosomy for 18p.

Monosomy for the short arm of chromosome 18 is one of the most frequent autosomal deletions observed. While most cases result from terminal deletion of 18p, 16% of cases reported were as a result of an unbalanced whole arm translocation resulting in monosomy 18p. The origin and structure of these derivative chromosomes were reported in only a few cases. We report the prenatal diagnosis and characterization of a new case of monosomy 18p as a result of an unbalanced whole arm translocation. Amniocentesis was performed at 15 weeks of gestation on a 34-year-old woman initially referred for advanced maternal age. Holoprosencephaly was identified by ultrasound at the time of amniocentesis. Karyotype analysis showed an unbalanced whole arm translocation between the long arm of one chromosome 18 and the long arm of one chromosome 22, 45,XX,der(18;22)(q10;q10), in all metaphases. In effect, the fetus had monosomy for 18p. Parental karyotypes were normal, suggesting a de novo origin for the der(18;22). Fluorescence in situ hybridization (FISH) analysis was performed with alpha-satellite probes D18Z1 and D14Z1/D22Z1 to identify the origin of the centromere on the der(18;22). Signal was observed with both probes, indicating that the centromere was composed of alpha-satellite DNA from both constituent chromosomes. Genotyping of the fetus and her parents with chromosome 18p STS marker D18S391 showed only the paternal 187 bp allele was present in the fetus, indicating that it was the maternal chromosome 18 involved in the der(18;22). This case and previous reports show that de novo unbalanced whole arm translocations are more likely to retain alpha-satellite sequences from the two chromosomes involved.

Adult↗
PubMed2001

The impact of the use of the isolated echogenic intracardiac focus as a screen for Down syndrome in women under the age of 35 years.

OBJECTIVE: The purpose of this study was to determine the public health impact of the routine offering of amniocentesis to women under the age of 35 years who have an isolated fetal echogenic intracardiac focus on second trimester ultrasound scan. STUDY DESIGN: A decision analytic model was designed that compared the accepted standard of second trimester triple marker screen for Down syndrome to a policy in which amniocentesis with an isolated echogenic intracardiac focus on ultrasound in addition to the triple marker screen is offered to all women in the United States who are <35 years of age. A sensitivity of 20%, an echogenic intracardiac focus screen positive rate of 5%, and a risk of Down syndrome of 1:1000 were assumed. A sensitivity analysis was performed that varied the screen positive rate, the sensitivity of echogenic intracardiac focus for Down syndrome, and the prescreen risk for Down syndrome in the population. RESULTS: With the baseline sensitivities, rates, and risks, the use of isolated echogenic intracardiac focus as a screen would result in an additional 118,146 amniocenteses performed annually to diagnose 244 fetuses with Down syndrome. These amniocenteses would result in 582 additional miscarriages. It would be necessary to perform 485 amniocenteses that would result in 2.4 procedure-related losses for each additional Down syndrome fetus that was identified. CONCLUSION: Although the echogenic intracardiac focus appears to be associated with a small increased risk of Down syndrome, its use as a screening tool in low-risk populations would lead to a large number of amniocenteses and miscarriages to identify a small number of Down syndrome fetuses.

Abortion, Spontaneous↗
PubMed2001

Outcome of pregnancy after prenatal diagnosis of umbilical vein varix.

Previous studies of umbilical vein varix diagnosed prenatally have been small, and the results have been contradictory. We wanted to determine whether prenatally diagnosed umbilical vein varix is associated with an increased risk of fetal anomalies or poor perinatal outcomes. We identified all cases of fetal intra-abdominal umbilical vein varix diagnosed on the basis of prenatal ultrasonography at Brigham and Women's Hospital between 1988 and 1998. Cases were reviewed to determine the presence of other sonographic findings as well as pregnancy and neonatal outcomes. We identified 25 cases and included those 23 for which follow-up was available. In 11 cases (48%), pregnancies and neonatal outcomes were normal, with full-term delivery, appropriate birth weight, and no evidence of anomalies. Three cases (13%) had preterm deliveries, and 1 had Kell isoimmunization requiring postnatal transfusion. In the remaining 8 cases (35%), structural anomalies were present. One fetus had a chromosomal abnormality (69,XXX). Prenatal diagnosis of fetal umbilical vein varix appears to be associated with a high rate of fetal anomalies. Detection of an umbilical vein varix should prompt a thorough examination of the fetus, including a fetal survey and echocardiogram. Isoimmunization should be ruled out, and consideration of karyotyping should be discussed if other anomalies are present.

Adult↗
PubMed2001

A case of chondrodysplasia punctata with features of osteogenesis imperfecta type II.

The osteogenesis imperfecta syndromes constitute a group of heterogeneous, heritable skeletal dysplasias. Of the 4 types, type II is the most severe, with an incidence of 1 per 55,000. It is characterized by malformed bones secondary to abnormal collagen type I synthesis. Affected fetuses are divided into 3 groups: A, B, and C. All groups have long bones described as "wrinkled" or "crumpled" secondary to repeated fractures. Many bones also show evidence of demineralization, which is especially evident in the bones of the face and calvaria. In groups A and C, the chest is generally small, with thickened and shortened ribs, and each rib has characteristic "beading" patterns secondary to repeated fracturing. Sonography has traditionally been successful in the diagnosis of osteogenesis imperfecta at an early gestational age. Chondrodysplasia punctata describes a heterogeneous group of skeletal disorders characterized by abnormal mineralization of bones during gestation. There are many different causes of it, but some of the specific subtypes include rhizomelic, X-linked dominant (also known as Conradi-Hünermann syndrome), X-linked recessive, and tibia-metacarpal. We report a case of severe X-linked dominant chondrodysplasia punctata, which sonographically had common features with osteogenesis imperfecta type II.

Adult↗
PubMed1999

Cystic fibrosis and chromosome abnormalities associated with echogenic fetal bowel.

OBJECTIVE: To determine the prevalence of cystic fibrosis mutations and chromosome abnormalities in the fetuses of a heterogeneous population of pregnant women referred for prenatal testing for echogenic fetal bowel. METHODS: Fetal or parental samples obtained after a second-trimester sonographic finding of echogenic fetal bowel were submitted to a referral diagnostic laboratory during a 2-year period. Results of DNA testing and karyotyping on these samples were analyzed to determine the prevalence of cystic fibrosis transmembrane reductase gene mutations and chromosome abnormalities. RESULTS: Of 244 cases tested, two fetuses were positive for two cystic fibrosis mutations. This rate (0.8% or two of 244) is 20 times higher than the general white population rate of one per 2500. In a third case, both parents were carriers but the fetus was not tested. Nine (8%) of 113 fetuses tested had one cystic fibrosis mutation. Of 106 fetuses for whom chromosome results were available, three (2.8%) fetuses had a chromosomal abnormality: two had trisomy 21 and one had Klinefelter syndrome. A fourth fetus carried a de novo, apparently balanced, 5;12 translocation. CONCLUSION: These laboratory results are representative of a broad spectrum of clinical settings and indicate a generalized increased risk associated with this sonographic finding. Therefore, when a second-trimester sonographic diagnosis of fetal echogenic bowel is made, fetal testing for both cystic fibrosis and chromosome abnormalities is warranted.

Adult↗
PubMed1999

Predicting the risk of cystic fibrosis with echogenic fetal bowel and one cystic fibrosis mutation.

OBJECTIVE: To assess fetal risk for cystic fibrosis when echogenic bowel and one cystic fibrosis mutation are detected. METHODS: A hypothetical cohort of 1000 women with singleton pregnancies and echogenic fetal bowel during the second trimester was used to determine the probability of cystic fibrosis when one cystic fibrosis transmembrane conductance regulator mutation was detected. The risk of cystic fibrosis was calculated using the range of prevalence of cystic fibrosis in fetuses with echogenic bowel reported in the literature. Risk calculations for fetuses of Ashkenazi Jewish, Northern European, African-American, Hispanic, and Asian descent accounted for carrier frequencies and mutation detection rates specific to each ethnic group. RESULTS: As the assumed prevalence of cystic fibrosis increases from 1-25%, the probability that a white fetus with one mutation and echogenic fetal bowel actually has cystic fibrosis increases from 4.8% to 62.5%. Assuming a 2% risk of cystic fibrosis with echogenic fetal bowel, an Ashkenazi Jewish fetus and an Asian fetus with echogenic bowel and one mutation have a 3.1% and 72% risk of cystic fibrosis, respectively. The probability of cystic fibrosis in a nonwhite fetus is between those two extremes. CONCLUSION: The probability of cystic fibrosis after detection of echogenic bowel and one cystic fibrosis mutation varied among ethnic groups. Even at the highest prevalence of cystic fibrosis, most white fetuses will not have cystic fibrosis. In nonwhite populations almost half of these fetuses will have cystic fibrosis, even at the lowest prevalence of cystic fibrosis.

Cystic Fibrosis↗
PubMed1998

Costello syndrome: phenotype, natural history, differential diagnosis, and possible cause.

We describe 8 patients affected with Costello syndrome including an affected sib pair and review the literature on 29 previously reported cases. We emphasize an association with advanced parental age, which is consistent with autosomal dominant inheritance with germline mosaicism. The pathogenesis appears to involve metabolic dysfunction, with growth disturbance, storage disorder appearance, acanthosis nigricans, hypertrophic cardiomyopathy, and occasional abnormalities of glucose metabolism. Although the cause is currently unknown, Costello syndrome is interesting because of a potential genetic-metabolic etiology.

Acanthosis Nigricans↗
PubMed1997

Cost-effectiveness of strategies used in the evaluation of pregnancies complicated by elevated maternal serum alpha-fetoprotein levels.

OBJECTIVE: To perform a cost-effectiveness analysis of various protocols used in the diagnostic evaluation of pregnancies complicated by elevated levels of maternal serum alpha-fetoprotein (MSAFP). METHODS: The variables incorporated in this model were the prevalence of relevant fetal anomalies; the sensitivity and specificity of MSAFP at 2.0 or 2.5 multiples of the median (MoM); and the sensitivity, specificity, cost, and safety of targeted ultrasound and amniocentesis. We expressed the cost-effectiveness of each strategy as the total cost of the diagnostic evaluation divided by the number of anomalous fetuses identified, yielding the cost per identified anomalous fetus. RESULTS: In a hypothetical cohort of 100,000 singleton pregnancies, a strategy of targeted ultrasound for MSAFP of at least 2.0 MoM detected 90 of 110 structurally abnormal fetuses, without iatrogenic fetal loss, at a cost of $5700 per anomalous fetus. A strategy of amniocentesis with karyo-type determination for MSAFP of at least 2.5 MoM detected 15 additional abnormal fetuses (87 structural abnormalities, ten autosomal aneuploidies, and eight sex chromosomal aneuploidies), with nine iatrogenic fetal losses, at an incremental cost of $46,100 per anomalous fetus. CONCLUSION: The increased cost and iatrogenic fetal loss rate may not justify the increased diagnostic yield of amniocentesis as compared with ultrasound in the evaluation of pregnancies complicated by elevated MSAFP.

Amniocentesis↗
PubMed1995

Interaction of hypertension and diabetes on renal function in black NIDDM subjects.

We studied renal function of 194 black subjects with duration of diagnosed NIDDM from 1 month to 36 years to determine the interaction of hypertension and diabetes on nephropathy. Renal function was assessed by isotopic GFR and RPF studies, and serum creatinine. One hundred seventeen of the 194 subjects had 24-hour urinary albumin excretion (AER). AER > 300 mg/24 h correlated with longer duration of NIDDM, decrease in GFR and RPF, and rise in serum Cr, and all subjects were hypertensive. AER 30 to 300 mg/24 h also correlated with a longer duration of NIDDM and 80% had hypertension. When 194 subjects were grouped according to duration of NIDDM and the presence or absence of hypertension, subjects who remained normotensive had normal renal function. In hypertensive subjects a decrease in GFR occurred with duration of NIDDM > 1 year and decrease in RPF with duration of NIDDM > 5 years. In hypertensive subjects with NIDDM > 10 years, 36% had impaired renal function (GFR < 80 ml/min/1.73 m2 or serum creatinine > 1.4 mg/dl) and 75% had microalbuminuria or clinical proteinuria. Within this group, those subjects who developed hypertension after their diagnosis of diabetes were likely to have evidence of nephropathy as compared to those subjects whose hypertension was diagnosed prior to or simultaneous with their diabetes: 17 of 20 (85%) versus 7 of 13 (54%), respectively (P = 0.05). These data provide insight into the relationship between hypertension and diabetes in the development of nephropathy in black NIDDM individuals.

Adolescent↗
PubMed1994

Biochemical and ultrasound screening for chromosomal abnormalities.

The utility of ultrasound screening for Down syndrome should be judged by whether the pertinent markers are reliably obtained and by whether they efficiently discriminate between fetuses with Down syndrome and euploid fetuses. Furthermore, the markers must be reliable at a gestational age early enough to be clinically useful. Screening for characteristic congenital malformations will result in a low detection rate of Down syndrome, and many of these cases will be identified only after 24 weeks of gestation. The subtlety of many of the ultrasound findings of Down syndrome in the second trimester requires significant technical expertise if ultrasonographic screening is to be used. Investigation thus far has centered on identifying patients at increased risk of Down syndrome, and no data are available on how much a normal ultrasound might decrease the risk associated with advanced maternal age or abnormal biochemical screening. Biochemical screening is currently able to detect at least 60% of Down syndrome in a low-risk population. The ultimate value of ultrasound may be to help further define the risk assigned by age and biochemical screening, to provide each patient with an aggregate risk. The decision on whether or not to offer an amniocentesis could then be based on the findings of these various examinations, with the goal to improve the accuracy of age or biochemical screening alone. It remains for studies to be done to determine whether ultrasound can in fact decrease the prior risk, and for large enough series and formulas to be published that allow us to specifically define how to integrate the information from each screen.

Adult↗
PubMed1994

Uniparental isodisomy for paternal 7p and maternal 7q in a child with growth retardation.

Uniparental isodisomy resulting from the simultaneous presence of isochromosomes of the p and q arms of a chromosome and absence of a normal homologue is an exceptionally rare event. We have observed a growth-retarded female infant in whom the normal chromosome 7 homologues were replaced by what appeared cytogenetically to be isochromosomes of 7p and 7q. Polymorphic microsatellite loci spanning the length of 7p and 7q were analyzed in the proband and her parents to ascertain the parental origin and extent of heterozygosity of the proband's rearranged chromosomes. These studies demonstrated that the 7p alleles of the proband were derived only from the father, the 7q alleles were derived only from the mother, and there was homozygosity for all chromosome 7 loci analyzed. The mechanisms leading to the formation of the proband's isochromosomes could reflect abnormalities of cell division occurring at meiosis, postfertilization mitosis, or both. We believe that the present case may result from incomplete mitotic interchange in the pericentromeric regions of chromosome 7 homologues, with resolution by sister-chromatid reunion in an early, if not first, zygotic division. Phenotypically, our proband resembled three previously reported cases of maternal isodisomy for chromosome 7, suggesting that lack of paternal genes from 7q may result in a phenotype of short stature and growth retardation.

Base Sequence↗
PubMed1994

Nonimmune hydrops fetalis.

In summary, NIHF is a heterogenous disorder resulting from a vast number of underlying pathologies. A thorough evaluation should be performed in all cases to attempt to establish the etiology. This requires a systematic approach that should logically proceed from least to most invasive testing. Despite increasing availability of treatment for some causes of NIHF, the prognosis for this condition in general remains poor. In cases of fetal or neonatal demise, autopsy should be encouraged to aid in confirming or making a diagnosis. It is especially important to rule out potentially treatable conditions, as well as genetic disorders with a risk of recurrence in future pregnancies.

Chromosome Aberrations↗
PubMed1993

Neonatal complications after the administration of indomethacin for preterm labor.

BACKGROUND: The use of indomethacin as a tocolytic agent in pregnant women appears to be accompanied by a low incidence of neonatal complications. However, the neonatal effects of indomethacin have been studied primarily in infants born after 32 weeks' gestation. This study was designed to examine the incidence of neonatal complications in very premature infants. METHODS: We identified 57 infants delivered at or before 30 weeks' gestation whose mothers had been treated with indomethacin for preterm labor and matched them with 57 infants whose mothers had not received indomethacin. The infants in the two groups were matched for sex, gestational age at delivery (mean [+/- SD], 27.6 +/- 2.0 weeks), exposure to betamethasone for 24 hours or more before delivery, and rupture of membranes 24 hours or more before delivery. RESULTS: There were no significant differences between the two groups in birth weight, Apgar scores, cord-blood gas values, frequency of multiple gestation, or incidence of respiratory distress syndrome. The proportion of infants who required exogenous surfactant was similar, as were ventilator settings at 24 hours, the incidence of chronic lung disease, and the incidence of sepsis. The infants exposed to indomethacin had a lower urine output and higher serum creatinine concentrations during the first three days after delivery. More indomethacin-exposed infants had necrotizing enterocolitis (29 percent vs. 8 percent, P = 0.005), intracranial hemorrhage grade II to IV (28 percent vs. 9 percent, P = 0.02), and patent ductus arteriosus (62 percent, vs. 44 percent, P = 0.05). More indomethacin-exposed infants with a patent ductus arteriosus required surgical ligation because of either a lack of initial response or a reopening of the duct after postnatal indomethacin therapy (50 percent vs. 20 percent of the unexposed infants, P = 0.05). CONCLUSIONS: Antenatal indomethacin therapy for preterm labor appears to increase the risk of serious neonatal complications in infants born at or before 30 weeks' gestation.

Cerebral Hemorrhage↗
PubMed1993

Facial features of infants exposed prenatally to cocaine.

Thirty two infants referred for in-patient genetics evaluation at the University of California at San Francisco, 1987-1992, were found to have a history of maternal cocaine use. Genetics reports and medical records were reviewed on all these infants to identify features distinctive for cocaine exposure. Among these 32 cases, 14 infants were exposed only to cocaine; 18 were exposed to alcohol and cocaine. The infants evaluated displayed a distinctive phenotype, consisting of neurologic irritability, large fontanels, prominent glabella, marked periorbital and eyelid edema, low nasal bridge with transverse crease, short nose, lateral soft tissue nasal buildup, and small toenails. Features consistent with the fetal alcohol syndrome appeared distinct and coexistent with the other described facial findings. Other severe abnormalities included cleft lip/palate, atypical facial cleft, abnormal BSER, intraventricular hemorrhages, arthrogryposes, and genitourinary abnormalities. Forty percent of the infants were born prematurely; 28% were small for gestational age; 43% showed head circumference values less than the 10th percentile. We conclude that these findings may be distinctive for a diagnosis of fetal cocaine syndrome; such findings should be further established by a future blinded prospective study of mothers and neonates.

Alcoholism↗