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E B Hook

Publications and source records attributed to E B Hook.

At least 127 records · Page 7Linked to original sources
PubMed1984

The frequency of 47,+21,47,+18, and 47,+13 at the uppermost extremes of maternal ages: results on 56,094 fetuses studied prenatally and comparisons with data on livebirths.

We examined the proportions (or so called "rates") of fetuses with 47,+21, 47,+18, or 47,+13 diagnosed prenatally in women at the upper extremes of age. Our analysis was prompted by results from a large scale European study of amniocentesis which indicated that after increasing exponentially from age 35 years, the proportions of the autosomal trisomies reached a peak at a specific age and then leveled off or declined at the upper end of the age range. We analyzed North American data on 56,075 fetuses studied because of no known cytogenetic risk factor (aside from maternal age). This is the largest series to date. For 47,+21, the data from amniocentesis studies provide no evidence for any drop in the rate of change of proportion with maternal age up to 49 years. There is, if anything, a trend in our data to a steepening in the exponential rate of change at the upper extreme of age (above 46 years). Data from livebirths on the Down syndrome phenotype are at least consistent with an exponential rate of increase in proportion affected up to age 49 years. For 47,+18 our data from prenatal diagnoses are more consistent with an exponential increase up to age 43 years and a level proportion (or "rate") after that. For 47,+13 no cases were observed above age 42 years, consistent with the drop in proportion affected above this age observed in the European series. We emphasize the possible effect of sampling fluctuation and reporting error upon these apparent trends.

Chromosome Aberrations↗
PubMed1984

Parental age and unbalanced Robertsonian translocations associated with Down syndrome and Patau syndrome: comparison with maternal and paternal age effects for 47, +21 and 47, +13.

Data are analysed on livebirths with trisomic syndromes associated with unbalanced Robertsonian translocations born from 1968 to 1981 and reported to the New York State Chromosome Registry. The maternal ages of reported cases were compared with those of the livebirths in the general population who were born in the same year. The number of translocations studied, the mean case-control differences in years in maternal age (and the standard errors of the mean) were respectively, as follows: D/21 mutants, n = 36, -0.1 (+/- 0.9); G/21 mutants, n = 46, +1.5 (+/-0.8); D/13 mutants, n = 16, +0.6 (+/-1.5); D/21 inherited, n = 12, -1.0 (+/-1.4); G/21 inherited, n = 3, -0.3 (+/-4.4); and D/13 inherited, n = 6, +2.1 (+/-2.4). There was little change in any category if the few cases diagnosed prenatally were included. Only the value for the G/21 mutants is significantly different from zero at the 0.05 level. (The results on G/21 mutants in maternal age are consistent with an earlier Japanese report of an increase of about 2 years over the control values.) The distribution of maternal ages suggests that G/21 mutants may be produced both by maternal age-independent and maternal age-dependent components. The data on D/21 mutants, however, do not indicate the negative association with maternal age reported in Japan. Differences between this study and the Japanese study in analyses of controls may explain this slight variation. But in any event both studies reveal no evidence for an increase in maternal age for unbalanced D/21 mutant or D/21 inherited translocations associated with Down syndrome. This is evidence against the hypothesis that relaxed selection during gestation, after recognition of pregnancy, accounts for the maternal age effects of 47, +21. In comparison with the results on Robertsonian translocations, the case-control differences in maternal age in years (and the standard errors of the mean) for 47, +21 for 2148 livebirths was +4.6 (+/-0.2), and for 2354 cases including those diagnosed prenatally was +5.3 (+/-0.2). The most likely value for an estimated total of 2292 cases of 47, +21 livebirths that would have been reported in the absence of prenatal diagnosis was +5.1 (+/-0.2). For 47, +13, for 98 livebirths the mean case-control difference in maternal age in years was +1.5 (+/-0.7) and for 116 cases including those diagnosed prenatally was +3.2 (+/-0.7).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1984

A search for a paternal-age effect upon cases of 47, +21 in which the extra chromosome is of paternal origin.

If there is a paternal-age effect for 47, +21, it would appear most likely to be present primarily, if not exclusively, in cases in which the extra chromosome is of paternal origin. To search for such an effect, data were reviewed from seven series reporting at least four cases of 47, +21 of paternal origin. The mean of the paternal age-maternal-age difference of such cases (dp) in each series was compared with the mean of the paternal-age differences of cases in the same series that were of maternal origin (dm). If the difference between these (dp - dm or delta) is greater than zero, then this would imply a positive paternal-age effect among cases of paternal origin, at least compared to those of maternal origin. In the seven series, the values of delta ranged from -2.2 years to +3.4 years, and there was no evidence in these comparisons for any consistent trend. A second analysis controlled for any effect of maternal-age variation upon this difference. Each case of paternal origin was matched with a case of maternal origin in the same series that was of the same maternal age. Of 60 cases of paternal origin, exact matches were found for 38. In these 38, the mean value of the difference in parental ages, dp - dm or delta, was negative, about -1.1 (+/- 5.1 years). The difference was highest for the nine cases of paternal origin in which the extra chromosome resulted from presumptive second-division non-disjunction, -1.8 (+/- 3.8 years).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Inherited structural cytogenetic abnormalities detected incidentally in fetuses diagnosed prenatally: frequency, parental-age associations, sex-ratio trends, and comparisons with rates of mutants.

Rates of structural chromosome abnormalities were analyzed in 24,951 fetuses studied prenatally in which there were no grounds to suspect an inherited abnormality. In about one in 200 prenatal cytogenetic diagnoses, an unexpected structural abnormality was found. The observed rate was 5.3 per 1,000, of which 1.7 per 1,000 were unbalanced and 3.6 per 1,000 balanced. The rate of inherited abnormalities was 3.1-3.7 per 1,000 (0.4-0.9 per 1,000 for unbalanced abnormalities and 2.6-2.8 per 1,000 for balanced abnormalities). The rate of mutants in this series was, by contrast, 1.6-2.2 per 1,000 (0.8-1.2 per 1,000 for unbalanced abnormalities and 0.8-1.0 per 1,000 for balanced abnormalities). The rate of balanced Robertsonian translocation carriers was 0.6 per 1,000 (about 0.25 per 1,000 for mutants and 0.35 per 1,000 for inherited abnormalities), and for other balanced abnormalities, 3.0 per 1,000 (about 0.6 per 1,000 for mutants and 2.4 per 1,000 for inherited abnormalities). The rates of unbalanced Robertsonian translocations was about 0.1 per 1,000, almost all of which were mutants. For supernumerary rearrangements, the rate was 0.9 per 1,000 (about 0.4 per 1,000 inherited and 0.5 per 1,000 mutant). The rates of all unbalanced (nonmosaic) inherited abnormalities (4.0-5.2 per 10,000) were intermediate between higher rates estimated in all conceptuses (9.1-15.8 per 10,000) and rates observed in newborns (1.5-2.5 per 10,000). This trend is probably attributable to fetal mortality associated with unbalanced rearrangements. The rates of balanced (nonmosaic) inherited abnormalities (26.0-28.0 per 10,000), however, were considerably higher than the rates in all conceptuses (13-16.7 per 10,000) or in all live births (12.2-16.0 per 10,000). The major difference was in the rate of inversions. The use of "banding" methods in the studies of amniocentesis but not in most of the live births or abortus studies probably contributes to at least some of these differences. One trend in parental age among the inherited abnormalities was noteworthy. Paternal age was elevated for inherited balanced reciprocal structural abnormalities of paternal origin but not of maternal origin. With regard to sex ratio, there was a greater proportion of females than males among the unbalanced rearrangements both inherited and mutant. There was no obvious sex difference among the balanced rearrangements.

Adult↗
PubMed1983

Chromosomal abnormality rates at amniocentesis and in live-born infants.

Regression-smoothed maternal age-specific rates of six different categories of cytogenetic abnormalities in recent large-scale prenatal cytogenetic studies were multiplied by independently derived fetal selection coefficients--factors that adjust for the excess likelihood of spontaneous loss of cytogenetically abnormal fetuses--to obtain estimated maternal age-specific rates of these categories of cytogenetic abnormalities in live-born infants. The derived rates apply to women whose only risk factor is advanced maternal age. The categories analyzed were 47,+21 (Down's syndrome), 47,+18 (Edwards' syndrome), 47,+13 (Patau's syndrome), 47,XXY (Klinefelter's syndrome), 47,XXX, and the group of other clinically significant abnormalities considered collectively. The rate of all clinically significant abnormalities considered together derived in this study was about five per 1,000 at age 35 years, 15 per 1,000 at age 40 years, and 50 per 1,000 at age 45 years.

Abnormalities, Multiple↗
PubMed1983

Spontaneous abortion and subsequent Down syndrome livebirth.

Analyses of two data sets are presented, one based on nationwide hospital discharges for the USA for 1970-1971, the other for Upstate New York vital record data for 1976-1981. Summary relative risks of a Down syndrome livebirth were calculated within the three maternal age categories below 20, 20-29, and 30 years and above for those with a history of one spontaneous abortion and for those with a history of two or more, compared to those with no reported previous abortions. There was significant heterogeneity by age and reproductive history in the relative risk of an affected child. In general the trends revealed that the younger the mother and the more the number of abortions, the higher the relative risk of a Down syndrome livebirth compared to the rates for women of the same age for those with no previous abortions. Extrapolation from average maternal age specific rates on Down syndrome imply a rate per 1000 livebirths somewhere in the range of 1.1 to 11.4 for women under 20 years with a history of one spontaneous abortion, of 5.2 to 13.4 for women under 20 years with a history of two or more spontaneous abortions, and of 1.0 to 2.4 for women 20 to 29 years with a history of two or more spontaneous abortions. (Average "background" livebirth rates in women under 30 years are, in contrast, in the range of about 0.5 to 1.0 per 1000 and for the average woman aged 35 years, at which prenatal diagnosis is usually felt to be indicated, 2.7 per 1000.) For those in the other categories these data did not reveal clinically significant effects upon average maternal age specific rates. It is emphasized that because of limitations in the data it is not possible to refine these risks by adjusting for karyotype, the age at which the abortions occurred, or other biologic and social factors associated with embryonic and fetal death. The implications of the analyses here for genetic counseling should be regarded as preliminary and tentative.

Abortion, Spontaneous↗
PubMed1983

Paternal age.

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Humans↗
PubMed1983

The distribution of chromosomal genotypes associated with Turner's syndrome: livebirth prevalence rates and evidence for diminished fetal mortality and severity in genotypes associated with structural X abnormalities or mosaicism.

The proportions of chromosomal genotypes associated with the Turner syndrome genotype (excluding those with a Y chromosome) in embryonic and fetal deaths, in fetuses diagnosed prenatally, and in living individuals were reviewed. The ratio of apparent non-mosaic 45,X to 45,X/46,XX mosaics was notably higher in a New York City series of embryonic and fetal deaths, 13.5 to 1, than in living individuals reported to the New York State Chromosome Registry, 3.6 to 1. The ratios of 45,X cases to those with 46,Xi(Xq) was 5.7 to 1 in living individuals, but was 112 to 0 in embryonic and fetal deaths, an even greater disparity, indicating the marked fetoprotective effect of more than one dose of some locus or loci on the long arm of the X chromosome. The results of review of data pertinent to the livebirth prevalence of the (apparent non-mosaic) 45,X genotype suggest a rate of about 5.7 per 100,000 livebirths (11.8 per 100,000 females) with 95% confidence limits of 2.6 per 100,000 to 10.8 per 100,000. The rate in fetuses diagnosed prenatally is 8/27,202, about 30 per 100,000. As a large proportion of these, perhaps 75%, would undergo spontaneous fetal death if not terminated electively, these figures are consistent with the direct estimate of livebirth rates. The rate of all those with X chromosome abnormalities (with a Y chromosome) associated with signs or symptoms that eventually lead to referral for cytogenetic study was estimated at a minimum of 10.7 per 100,000 livebirths, (22.2 per 100,000 females).

Chromosomes, Human↗
PubMed1983

Trends in utilization of prenatal cytogenetic diagnosis by New York State residents in 1979 and 1980.

It is estimated that 35.3 per cent of pregnant New York State women age 35 or over underwent cytogenetic diagnosis in 1980 as compared to 28.7 per cent in 1979. Rates varied sharply by county. In several small counties far from genetic centers, no 1980 cytogenetic diagnostic studies were reported in women 35 or over while in New York City the rate was 41 per cent. In one county with an active genetic center the rate appears to have plateaued at 30 per cent.

Adult↗
PubMed1983

Chromosome abnormalities and spontaneous fetal death following amniocentesis: further data and associations with maternal age.

The pooled results are presented of two North American surveys concerning spontaneous fetal deaths of conceptuses with cytogenetic abnormalities diagnosed prenatally whose mothers had declined elective abortion. The rate of fetal death of those with nonmosaic genotypes associated with Down syndrome was 30.1% (95% confidence interval of 19.0%-42.0%), which is almost identical with the difference of 30% previously estimated between rates observed at amniocentesis and in live births. The fetal death rate for (nonmosaic) 47,+18 was 68.0% (95% confidence interval of 46.5%-85.1%), close to the estimated difference of 75% between rates at amniocentesis and in live births for this genotype. For other nonmosaic genotypes, the rates (and 95% confidence intervals) were: 47,+13, 42.9% (9.9%-81.6%); 47,XXX, 0% (0%-9.0%); 47,XXY, 8.1% (0.8%-11.0%); 47,XYY, 3.0% (.08%-15.8%); for balanced translocations and inversions, 2.8% (0.3%-9.8%); and for markers, variants, and fragments, 0% (0%-12.8%). For 45,X, the rate was 75.0% (42.8%-94.5%), in contrast to the rate for 46,XX/45,X of 10.5% (1.3%-33.1%) and for structural X abnormalities associated with Turner syndrome of 0% (0%-60.2%). The rate for nonmosaic 45,X is significantly different from that for either of the other two categories associated with Turner syndrome. The maternal age of nonmosaic 47,+21 fetuses that survived to live birth was 39.1 +/- 6.2, not significantly different from the rate for fetal deaths: 39.5 +/- 3.8. The observations provide no support for opposing hypotheses by other groups that maternal age is positively or negatively associated with fetal death of 47,+21 conceptuses. For other chromosome abnormalities, maternal ages of fetal deaths are slightly lower than for live births, but none of the differences are significant. The rates of spontaneous fetal deaths derived here are likely to be pertinent to genetic counseling. Their use in adjusting the rates of abnormalities diagnosed at amniocentesis will enable derivation of predicted contemporary live-birth prevalence rates of abnormalities that would be observed in absence of selective abortion.

Adult↗
PubMed1983

Decreased HLA heterogeneity in parents of children with Down syndrome.

HLA-A and B antigens were determined in a study of 37 couples and their children with trisomy 21 Down syndrome (DS), using a standard microlymphocytotoxicity test. The comparison groups included 76 couples and their healthy children. All individuals were Caucasians from the same geographical area, and there was no history of consanguinity. The parents of children with DS did not show an association with a specific HLA antigen or haplotype. Sixteen of the 37 couples (43.24%) having children with DS share two or more antigens at the A and/or B locus. This was significantly higher than the proportion in the control group (6/76, or 7.88%). Of the 16 couples having children with DS and sharing two or more antigens, eight had a haplotype in common, in contrast with only two couples in the control group. The data suggest that sharing of parental HLA-A and B antigens may be related either to the occurrence of trisomy 21 zygotes or to prenatal survival of affected embryos and fetuses.

Adult↗
PubMed1983

Down syndrome rates and relaxed selection at older maternal ages.

Preferential survival in older mothers of fetuses with Down syndrome has been proposed as contributing to the maternal-age effect of this condition. If correct, this provocative hypothesis, which may be termed "relaxed selection," has major implications for approaches to prevention of Down syndrome live births in older women. Several predictions of this hypothesis are examined here by comparisons of parental ages among various populations. These revealed that: (1) mean maternal age of Down syndrome live births is slightly lower than that of Down syndrome spontaneous fetal deaths; (2) mean maternal age of those with mutant D/21 translocation Down syndrome is about the same as that of controls; (3) the ages of Down syndrome mothers who have Down syndrome live births is slightly lower than ages of Down syndrome mothers who have unaffected live births; and (4) in recent data on 47, +21 cases in which the extra chromosome 21 is of paternal origin, the mean maternal ages are 4-5 years lower than the maternal ages of cases of maternal origin (in contrast to earlier reports). All of these observations are contrary to the hypothesis that relaxed selection contributes significantly to the maternal-age association of Down syndrome. If there is any effect of relaxed selection, it is likely to be very weak and/or act primarily upon abortions that occur before recognition of pregnancy.

Adult↗
PubMed1983

Rates of mutant structural chromosome rearrangements in human fetuses: data from prenatal cytogenetic studies and associations with maternal age and parental mutagen exposure.

In 27,225 prenatal cytogenetic studies of amniotic fluid reported to the New York State Chromosome Registry and the United States Interregional Chromosome Register System, there were 61 cases with a structural chromosomal abnormality not known inherited, a rate per 1,000 of 2.24. Of these 33, 1.21 per 1,000 were known de novo and nonmosaic; consequently, the rate of events resulting from germinal mutation is highly likely to be between these two limits. The rates per 1,000 of unbalanced abnormalities were 0.59-1.29; of balanced abnormalities, 0.62-0.96; of balanced Robertsonian translocations, 0.22-0.29; and of unbalanced Robertsonian translocations, 0.07-0.11. The rates of fetuses with supernumerary markers and fragments were unexpectedly high: 0.26-0.70 per 1,000. These abnormalities were associated with increased maternal age (38.0 +/- 5.4 to 38.4 +/- 3.6 compared to 35.6 +/- 4.3 in controls), but even after adjustment for the bias to preferential study of older women, the observed rates of these supernumerary abnormalities were greater than would be expected from live-birth studies or rates estimated in all recognized conceptuses. There were trends to elevated maternal age for the group of all balanced rearrangements, and to diminished maternal age for the nonsupernumerary, non-Robertsonian unbalanced rearrangements. In 136 women studied primarily because of exposure to a putative mutagen, a de novo deletion and an inversion not known inherited were detected. The rate of abnormality in these 136, 1.47%, was significantly greater than the rate of abnormality in the remainder: 0.14%-0.22%.

Adult↗
PubMed1982

Rates of trisomies 21, 18, 13 and other chromosome abnormalities in about 20 000 prenatal studies compared with estimated rates in live births.

Data were analyzed on the results of 19675 prenatal cytogenetic diagnoses reported to two chromosome registries on women aged 35 or over for whom there was no known cytogenetic risk for a chromosome abnormality except parental age. The expected rates at amniocentesis of 47, + 21; 47, + 18; 47, + 13; XXX; XXY; XYY; and other clinically significant cytogenetic defects by maternal age were obtained from a regression analysis on the observed rates, using a first degree exponential model. After an adjustment for maternal age, these rates were compared with previously estimated rates by maternal age in live births. The rates of 47, + 21 at amniocentesis and live birth are approximately parallel, with the latter about 80% of the amniocentesis rates. The rates of 47, + 18 at amniocentesis and live birth are approximately parallel, with the live birth rates about 30% of the amniocentesis rates, consistent with high fetal mortality of 47, + 18 after amniocentesis. The rates of 47, + 13 at amniocentesis indicate an increase in maternal age that is not as marked as that previously estimated in live births. The rates at amniocentesis for XXX and XXY increase with maternal age, with the rates of XXY almost identical to those estimated previously in live births, suggesting no late fetal mortality of XXY. The rates of XYY show a slight decrease with maternal age also consistent with little late fetal mortality of XYY. No consistent trend with age is seen for the pooled group of other clinically significant defects.

Adult↗
PubMed1982

Age of ascertainment: an index of relative severity of cytogenetic conditions.

Different cytogenetic conditions which may produce the same phenotype can be defined as phenotypically homologous. Such conditions may differ in their mean severity. It is suggested here that the age of ascertainment by cytogenetic laboratories of individuals with chromosomal abnormalities is a useful relative index of severity. Three nonmosaic cytogenetic conditions (47, + 21, 47, + 18, and 45, X) were compared with their respective mosaic homologues, using data reported by 38 laboratories participating in the New York State Chromosome Registry. For all three comparisons the mean age of ascertainment and the proportion ascertained in individuals older than 1 yr were greater for the mosaic than the nonmosaic homologues, consistent with the utility of this variable as an index of relative severity. A comparison was also undertaken between (nonmosaic) 45, X and (nonmosaic) 46, long-arm isochromosome-X forms of Turner's syndrome. Only 2% of the latter cases were ascertained under age 1 yr, compared to 25% of the former. The difference is consistent with lesser phenotypic severity of the isochromosome form of Turner's syndrome--a finding of which is independently suggested by a trend in collected heterogeneous case reports.

Adolescent↗