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T Hassold

Publications and source records attributed to T Hassold.

At least 55 records · Page 3Linked to original sources
PubMed1988

Molecular studies of the parental origin and nature of human X isochromosomes.

X-chromosome restriction fragment length polymorphisms were used to determine the parental origin of the isochromosome in nine individuals with an i(Xq) or idic(Xq). We were able to specify the parental source of eight of the nine isochromosomes, with six being maternal and two paternal in origin. In two cases, one i(Xq) and one idic(Xq), we used Xq markers to determine the level of heterozygosity in the isochromosome. Each was homozygous at all tested loci, suggesting that each originated from a single X chromosome and not from an exchange of material between two X's.

Adolescent↗
PubMed1988

Cytogenetic and molecular analysis of sex-chromosome monosomy.

X chromosome- and Y chromosome-specific DNA probes were used to study different aspects of the genesis of sex-chromosome monosomy. Using X-linked RFLPs, we studied the parental origin of the single X chromosome in 35 spontaneously aborted and five live-born 45,X conceptions. We determined the origin in 35 cases; 28 had a maternal X (Xm) and seven had a paternal X (Xp). There was a correlation between parental origin and parental age, with the Xp category having a significantly reduced mean maternal age by comparison with the Xm group. Studies aimed at detecting mosaicism demonstrated the presence of a Y chromosome or a second X chromosome in three of 33 spontaneous abortions, a level of mosaicism much lower than that reported for live-born Turner syndrome individuals.

Chromosome Banding↗
PubMed1987

Analysis of nucleolar organizing regions in parents of trisomic spontaneous abortions.

Nucleolar organizing region (NOR) variants of parents of karyotyped spontaneous abortions were examined to test the hypothesis that double NORs are important in the genesis of acrocentric trisomies. We were unable to detect any significant difference in the frequency or types of NOR variants between parents of acrocentric trisomies and parents of other types of spontaneous abortions, nor did we identify a double NOR in either group. Thus, it seems unlikely that double NORs are of major significance in the etiology of acrocentric trisomies.

Abortion, Spontaneous↗
PubMed1987

Cytogenetic and molecular studies of trisomy 13.

Chromosome heteromorphisms, restriction fragment length polymorphisms, or both were used to study the parental origin of 33 cases of simple trisomy 13 and eight cases of translocation trisomy 13. The most common origin for the simple trisomies was non-disjunction at maternal meiosis I, while for the translocations an equal number of paternally and maternally derived cases was observed. In seven of the simple trisomies, information was obtained from both the cytogenetic and molecular markers, making it possible to study recombination between the two non-disjoined chromosomes. Five of the seven cases involved errors at meiosis I, with crossing over being detected in two of three cases of maternal origin and in one of two cases of paternal origin. This indicates that absence of recombination because of pairing failure is unlikely to be of major importance in the genesis of trisomy 13.

Chromosome Mapping↗
PubMed1987

Does the karyotype of a spontaneous abortion predict the karyotype of a subsequent abortion? Evidence from 273 women with two karyotyped spontaneous abortions.

At least two spontaneous abortions were karyotyped in 273 women during cytogenetic surveys in New York City and Honolulu. These pairs were analyzed using maximum-likelihood logistic-regression analysis to adjust for maternal age and location. There was a significantly increased risk for a chromosomally normal spontaneous abortion after a previous abortion with a normal karyotype. There was no increased risk for trisomy in a second spontaneous abortion following either a previous trisomic abortion or an abortion with another abnormal karyotype. This is unexpected, given the increased risk for trisomy found among live births and at prenatal diagnosis in young women with a previous trisomic birth. The most likely explanation is that the increased recurrence risk for trisomy is restricted to trisomy for only one or a few chromosomes, for reasons such as parental trisomy mosaicism. These data predict no increased risk of chromosome abnormality in future pregnancies after either (1) spontaneous abortions with trisomies of a kind that are always lethal in utero or (2) multiple early abortions in the presence of normal parental karyotypes.

Abortion, Habitual↗
PubMed1985

Maternal age-specific rates of numerical chromosome abnormalities with special reference to trisomy.

The effect of maternal age on the incidence of chromosomally normal spontaneous abortion and different categories of chromosome abnormality among all clinically recognized human pregnancies was evaluated. The results provide no evidence for a significant association of age with sex chromosome monosomy or polyploidy, but clearly demonstrate an effect of age on the frequency of trisomy and chromosomally normal spontaneous abortions. Estimated maternal age-specific rates of trisomy among all recognized pregnancies were calculated and suggest that a majority of oocytes of women aged 40 years and older may be aneuploid.

Abortion, Spontaneous↗
PubMed1985

Determination of the parental origin of sex-chromosome monosomy using restriction fragment length polymorphisms.

The parental origin of the single X chromosome in sex-chromosome monosomy was evaluated by comparing restriction fragment length polymorphisms (RFLPs) of 10 spontaneous aborted 45,X conceptions with those of their parents. Seven X-linked marker loci were used, and we were able to specify the origin of the X in nine cases, with six being maternally and three paternally derived. These results demonstrate the efficiency of the technique and show that the single X chromosome in 45,X spontaneous abortions can be derived from either parent.

Abortion, Spontaneous↗
PubMed1984

Parental origin of autosomal trisomies.

Chromosome heteromorphisms of parents and their trisomic spontaneous abortions were compared in an attempt to determine the parental origin of 204 single trisomies, including cases of trisomy 3, 4, 9, 13, 14, 15, 16, 21 and 22, nine mosaic trisomies and nine double trisomies. Non-disjunction at maternal meiosis I was the most likely source of the additional chromosome for all trisomies studied, including the mosaics, and this was the case at all maternal ages. However, trisomy 21 had a significantly increased proportion of paternally derived cases by comparison with all other trisomies. Consideration of the sex ratio in cases of trisomy 21 of known parental origin suggests that there is an excess of males associated with paternal first meiotic division non-disjunction. The fact that this mechanism of origin is more prevalent in trisomy 21 may well explain why there is an excess of males associated with this abnormality but not with other autosomal trisomies.

Abortion, Spontaneous↗
PubMed1984

Temporal changes in chromosome abnormality rate in human spontaneous abortions: evidence for an association between sex-chromosome monosomy and trisomy 16.

As part of a cytogenetic survey of human spontaneous abortions, the relative frequencies of different categories of chromosome abnormalities were evaluated for possible temporal changes. Three classes of chromosome abnormalities showed significant linear trends; sex-chromosome monosomy and tetraploidy decreased over the study period, while trisomy increased. The increase in trisomy was largely attributable to trisomy 16, which showed a two-fold increase over the duration of the study. The linear increase in trisomy 16 was inversely related to sex-chromosome monosomy. This effect was restricted to women over 30 yr of age and was most pronounced among Oriental women.

Abortion, Spontaneous↗
PubMed1984

The relationship of maternal age and trisomy among trisomic spontaneous abortions.

The relationship between maternal age and trisomy was examined by comparing mean ages of 954 trisomic spontaneous abortions with those of live births ascertained at the same study center. The overall mean for trisomy was highly significantly elevated over that of the newborns. The age effect was most pronounced for trisomies involving the small chromosomes, with trisomies 13, 14, 15, 16, 17, 18, 20, 21, and 22 all having significantly increased ages by comparison with the control population. However, the majority of trisomies involving large or medium-sized chromosomes also had elevated mean maternal ages, suggesting that most, if not all, human trisomies are associated with increasing age of the mother. Additional variation in the age effect was observed among trisomies involving similar-sized chromosomes, indicating that factors other than chromosome size also influence the relationship between increasing age and trisomy.

Abortion, Spontaneous↗
PubMed1983

The effect of chromosome constitution on growth in culture of human spontaneous abortions.

The effect of chromosome constitution on growth in culture was evaluated by comparing the length of time in culture until cytogenetic analysis among chromosomally normal and abnormal spontaneous abortions. We observed a significant effect of both tissue type and cell type, but not chromosome constitution, on the rate of growth of the cultures.

Abortion, Spontaneous↗
PubMed1983

Sex ratio in spontaneous abortions.

An analysis of sex ratio was made for chromosomally normal and trisomic spontaneous abortions identified in a cytogenetic survey of spontaneous abortions. For the chromosomally normal group, the extent of maternal contamination among 46, XX abortions was determined by comparing chromosome heteromorphisms of the parents with those from the tissue samples. The sex ratio among the normal abortions was then estimated to be approximately 1.30, after correcting for the maternal contaminants and 46, XX hydatidiform moles of androgenetic origin. This estimate is significantly higher than values typically reported for newborns, indicating an effect of X-linked genes acting in utero. The sex ratio among trisomic abortions identified in the present study and in four other cytogenetic studies of spontaneous abortions was also significantly greater than 1.0, but not as high as the estimates of sex ratio for the chromosomally normal abortions. There was considerable variability among individual trisomies, and possible mechanisms leading to this variation are discussed.

Abortion, Spontaneous↗
PubMed1982

Mosaic trisomies in human spontaneous abortions.

Data from a cytogenetic survey of spontaneous abortions were examined to determine the incidence and origin of mosaic trisomies in this population. The overall frequency of mosaicism among trisomies was approximately 5%, but the level of mosaicism varied significantly among trisomies, being much higher for the nonacrocentric than for the acrocentric trisomies. Evidence from chromosome heteromorphism analysis suggests that the extra chromosome in mosaic trisomies usually has a meiotic origin.

Abortion, Spontaneous↗
PubMed1980

Effect of maternal age on autosomal trisomies.

The effect of maternal age on the genesis of trisomy was studied by comparing data from 362 trisomic and 790 chromosomally normal spontaneous abortions. As a group the trisomies were associated with a substantial increase in maternal age but there were considerable differences in the magnitude of the effect for different trisomies. The effect of increasing maternal age was most pronounced for trisomies involving the small chromosomes, both acrocentric and non-acrocentric. However, trisomy 16 was conspicuously different from trisomies for all the other small chromosomes, both in the reduced importance of increased maternal age and in the high frequency with which it occurred. The effect of increasing maternal age on trisomies for chromosomes in groups A, B and C was less clear than that for the small chromosomes. However, the evidence suggested that trisomy for these chromosomes was associated with a moderate increase in maternal age. It was suggested that the maternal age-dependent trisomies might result from precocious disjunction of the bivalents and random segregation of the resulting univalents, a process which would affect chromosomes with the fewest number of chiasmata and which might be more prevalent if oocytes of older women. It was further suggested that true non-disjunction, that is, the failure of bivalents to separate at anaphase, might also result in the production of trisomies. This process might be independent of, or only slightly influenced by, increasing maternal age but be affected by the presence of large blocks of heterochromatin.

Abortion, Spontaneous↗
PubMed1980

A cytogenetic study of 1000 spontaneous abortions.

Cytogenetic analysis of 1000 spontaneous abortions showed 463 to have an abnormal chromosome constitution. The proportion of chromosome abnormalities varied with the gestational age of the abortus and the type of tissue cultured but was not significantly different among the five racial groups represented in the study population. It was suggested that differences in the rate of chromosome abnormalities among cytogenetic studies of spontaneous abortions were the result of methodological differences in sample selection rather than real biological variation among study populations. The only factor found to be unequivocally associated with the aetiology of chromosome abnormalities in spontaneous abortions was increasing maternal age in trisomies.

Abortion, Spontaneous↗
PubMed1979

Origin of trisomies in human spontaneous abortions.

Chromosome heteromorphisms of 34 trisomic abortuses and their parents were compared to determine the origin of the extra chromosome. Fourteen of the trisomies were maternal in origin, ten resulting from a first-meiotic-division error and four from either first- or second-meiotic-division errors. No paternally derived trisomy was identified.

Abortion, Spontaneous↗
PubMed1979

Cytogenetic and clinical studies in five cases of inv dup(15).

Inv dup(15) is a clinically significant bisatellited derivative of chromosome 15. Five unrelated patients with this abnormality are described and compared with ten confirmed and nine suspected cases in the literature. Mental and developmental retardation, hypotonia, behavioral disturbances, seizures, abnormal dermatoglyphics, and mild somatic anomalies were the most consistent findings. The extra chromosomes in our patients were identified with the aid of various techniques, including distamycin A/DAPI banding. A comparison of satellite polymorphisms suggested that the rearrangements frequently arose by meiotic nonsister chromatid exchange and second-division nondisjunction. A maternal origin was indicated in two cases, and parental ages were distinctly elevated.

Abnormalities, Multiple↗