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Biomedical subjects

E B Hook

Publications and source records attributed to E B Hook.

At least 145 records · Page 8Linked to original sources
PubMed1982

Contribution of chromosome abnormalities to human morbidity and mortality.

Estimates of the association of chromosome aberrations with various adverse health outcomes are as follows: embryonic and fetal death (5-28 weeks), 33%; stillbirths, 5-10%; infant and early childhood death, 5-7%; retardation (IQ less than 50), 20-35%; (IQ 50-69), 5-15%; criminality an d retardation or psychiatric disturbance in males, 3%; other criminality, 0.3-0.8%; birth defects, 2.5-8%; heart defects, 10%; subfertility or infertility, 2-8%; multiple miscarriages, less than 1 to 13%; male pseudohermaphroditism, less than 25%; and primary amenorrhea, 25%. Variations in rates reflect statistical fluctuations and variations in the selection of populations for study. The estimates are based on currently used techniques; cryptic structural rearrangements may also contribute significantly to these outcomes.

Chromosome Aberrations↗
PubMed1981

Comparison of mathematical models for the maternal age dependence of Down's syndrome rates.

The maternal age dependence of Down's syndrome rates was analyzed by two mathematical models, a discontinuous (DS) slope model which fits different exponential equations to different parts of the 20-49 age interval and a CPE model which fits a function that is the sum of a constant and exponential term over this whole 20-49 range. The CPE model had been considered but rejected by Penrose, who preferred models postulating changes with age assuming either a power function X10, where X is age or a Poisson model in which accumulation of 17 events was the assumed threshold for the occurrence of Down's syndrome. However, subsequent analyses indicated that the two models preferred by Penrose did not fit recent data sets as well as the DS or CPE model. Here we report analyses of broadened power and Poisson models in which n (the postulated number of independent events) can vary. Five data sets are analyzed. For the power models the range of the optimal n is 11 to 13; for the Poisson it is 17 to 25. The DS, Poisson, and power models each give the best fit to one data set; the CPE, to two sets. No particular model is clearly preferable. It appears unlikely that, with a data set from any single available source, a specific etiologic hypothesis for the maternal age dependence of Down's syndrome can be clearly inferred by the use of these or similar regression models.

Down Syndrome↗
PubMed1981

Unbalanced Robertsonian translocations associated with Down's syndrome or Patau's syndrome: chromosome subtype, proportion inherited, mutation rates, and sex ratio.

Summary data are presented on 168 D/21 and 131 G/21 translocation trisomies reported to the New York State Chromosome Registry. By combining these data with others from the literature it is estimated that about 59% of D/21 cases are the result of mutation in hte parental generation; the rest are translocations inherited from parental carriers (39% maternal, 3% paternal). The proportion of mutants is about 10% greater for 14/21 cases and significant lower for 13/21 cases. Of G/21 cases 93% are mutant, about 6% of maternal origin, and 1% of paternal origin. All the mutant cases involve 21/21 rearrangements. Estimated mutation rates per 10(5) gametes for translocation trisomies in affected livebirths are 0.1 for 21/13, 0.5 to 0.9 for 21/14, and 1.1 to 1.4 for 21/21. The rates for 21/15 and 21/22 translocation trisomies are probably all conservatively less than 0.1 per 10(5) gametes. Of interchange trisomy Patau's syndrome, about 60% of cases are mutant; the rest are translocations inherited from a parental carrier (about 25% maternal, 15% paternal). The mutant proportion is about 90% for 13/13 cases and about 45% for 13/14 cases. The estimated mutation rates for 13/13 and 13/14 interchange trisomies are each about 0.5 per 10(5) gametes; te rate for 13/15 interchange trisomies is less than 0.1 per 10(5) gametes. A male excess is observed for D/21 (sex ratio = 1.70) and G/21 (sex ratio = 1.38) interchange Down's syndrome, and a female excess for D/13 interchange Patau's syndrome (sex ration = 0.77), trends similar to those seen in the respective 47, trisomies associated with these phenotypes.

Chromosomes, Human, 13-15↗
PubMed1981

Sister chromatid exchange in newborns.

Sister chromatid exchanges (SCE) were analyzed in the cord and postnatal blood of controlled groups of low and high birth weight infants to detect possible associations between abnormal birth weight and SCE frequency. Structural chromosome aberration rates had previously been evaluated for all infants, and possible correlations between aberration and SCE rates were sought. No correlation was found between neonatal or postnatal SCE frequency and birthweight, nor was there evidence of association of chromosome aberration rates with SCE frequency. In all groups of infants, however, mean postnatal SCE frequencies were significantly lower than mean neonatal SCE frequencies.

Birth Weight↗
PubMed1981

Somatic chromosome breakage in low birth weight newborns.

To detect any association between birth weight and frequency of aberration or cell damage and to investigate possible postnatal environmental effects on chromosomes, we studied controlled groups of newborn low and high birth weight infants and screened for chromosome breakage and rearrangement in cord blood and postnatal peripheral blood. No evidence of a correlation of neonatal chromosome damage and birth weight was found. A significant increase of chromosome damage in postnatal blood of intrauterine-growth-retarded infants is interpreted as a reflection of postnatal environmental factors.

Birth Weight↗
PubMed1981

Temporal increase in the rate of Down syndrome livebirths to older mothers in New York State.

In New York State exclusive of New York City the standardised rate of Down syndrome in livebirths to women 35 and over reported on birth certificates increased 30% in 1970 and later years, compared to the rate in 1965 and 1969. In contrast, there was no change in those under 35. A separate investigation revealed that selective temporal differences in reporting of cases born to older mother did not account for the change. A similar increase in rates of cases born to older but not younger mothers in 1970 and later years has also been reported from Manitoba. These observations may be pertinent to apparent discrepancies between livebirth rates of Down syndrome and those reported at amniocentesis.

Down Syndrome↗
PubMed1981

Down's syndrome: percentage reporting on birth certificates and single year maternal age risk rates for Ohio 1970-79: comparison with upstate New York data.

Estimates of single year maternal age risk rates for Down's Syndrome births to White residents of Ohio over the period 1970-79 are reported. The rates were estimated from birth certificate data, which first necessitated estimating the percentage of reporting of Down's Syndrome on Ohio birth certificates. Using data from cytogenetic laboratories within the state, percentages of Down's Syndrome cases reported were found to be 36.5 (319/875) for White and 33.9 (342/1,010) overall. Final single year maternal age risk rates reported here are corrected for underreporting using these figures. They should be useful for genetic counselors and obstetricians. Comparisons of observed, uncorrected single year maternal incidence rates were made within Ohio 1970-74 vs 1975-79, and between Ohio and upstate New York for various time periods using both a hierarchial log-linear model for multiway cross-tabulations and a weighted least squares solution. All comparisons showed excellent agreement, indicating no evidence for temporal or geographic differences and implying that environmental factors are unimportant in determining single year maternal age incidence rates in Down's Syndrome for the time periods and populations studied.

Adolescent↗
PubMed1981

Paternal age and Down syndrome in British Columbia.

Among Down syndrome cases born in 1964--1976 reported to the British Columbia Registry for Handicapped Children, the mean parental age was about half a year greater than in the entire population of live births after controlling for maternal age, a difference significant at the .05 level. After adjustment for maternal age, a regression analysis was consistent with an increase of 1.024-fold for each year of paternal age. Among Down syndrome cases in 1952--1963, however, for which ascertainment appears likely to be less complete, there was no evidence for a significant paternal age effect. The reasons for the variation between the two groups investigated here and the heterogeneity in results among studies of other populations are discussed.

British Columbia↗
PubMed1981

Mutation rates for unbalanced Robertsonian translocations associated with Down syndrome. Evidence for a temporal change in New York State live births 1968--1977.

The mutation rate for translocation Down syndrome was investigated for New York State live births for each of the years 1968--1977 using data from the New York State Chromosome Registry. The overall rate was 2.5 X 10(-5) per gamete (1.4 X 10(-5) for G/21 and 1.0 X 10(-5) for D/21 rearrangements), about 20% higher than rates previously reported by two other studies. For the first 5-year period, 1968--1972, the rate was 1.8 X 10(-5), and for the second 5-year period, 3.1 X 10(-5); there was an abrupt change in 1973 and 1974 to rates more than twice that in the 3 preceding years. These rates were derived by applying completeness estimates for all cases of Down syndrome, mostly 47,trisomy 21, in the jurisdiction to cases with translocation Down syndrome mutations. If completeness corrections are ignored and only the minimum boundaries of rates are considered, however, the increase in 1973 and 1974 was even greater compared with the previous 3 years. The trends, if not attributable to an undetected artifact, may have been caused by an increased frequency of mutant zygotes and/or enhanced intrauterine survival of mutant translocations.

Down Syndrome↗
PubMed1981

Rates of chromosome abnormalities at different maternal ages.

Estimates are made of the rates of all clinically significant cytogenetic abnormalities in live births by 1-year maternal age intervals ranging from 15 to 49. Down syndrome results from the most prevalent clinically significant cytogenetic abnormality, yet the rates of disorders associated with other cytogenetic abnormalities also increase with maternal age and significantly contribute to the overall rate at the older ages. The estimated rate of all clinically significant cytogenetic abnormalities rises from about 2 per 1000 (1 per 500) at the youngest maternal ages to about 2.6 per 1000 (1 per 270) at age 30, 5.6 per 1000 (1 per 80) at age 35, 15.8 per 1000 (1 per 60) at age 40, and 53.7 per 1000 (1 per 20) at age 45.

Adolescent↗