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Biomedical subjects

D A Aitken

Publications and source records attributed to D A Aitken.

15 recordsLinked to original sources
PubMed1992

Variation in the levels of pregnancy-specific beta-1-glycoprotein in maternal serum from chromosomally abnormal pregnancies.

Human pregnancy-specific beta-1-glycoprotein (SP1) was assayed retrospectively in stored maternal serum (MS) samples from 82 chromosomally abnormal pregnancies and 377 matched controls. The median MSSP1 concentration in 48 Down's syndrome pregnancies was significantly elevated at 1.17 multiples of the control median (MOM), and significantly reduced (0.5 MOM) in a group of eight cases of unbalanced translocations. There was no significant difference in median SP1 concentrations in cases of trisomy 18, trisomy 13, balanced translocations, or sex chromosome abnormalities. A comparison with human chorionic gonadotrophin results in the same series of samples indicates that SP1 is a less sensitive predictor of Down's syndrome pregnancies.

Chorionic Gonadotropin↗
PubMed1991

Prenatal screening for chromosome abnormalities using maternal serum chorionic gonadotrophin, alpha-fetoprotein, and age.

Human chorionic gonadotrophin (hCG) levels were assayed retrospectively in stored maternal serum samples from 78 chromosomally abnormal pregnancies and 410 controls matched for gestation and maternal age. The median serum hCG concentration in 49 pregnancies with Down's syndrome was significantly elevated, at 2.18 multiples of the normal median. Significantly reduced hCG concentrations were found in a group of four trisomy 18 pregnancies (all less than 0.4 multiples of the median). Eight cases of unbalanced chromosome rearrangements appeared to show some lowering of hCG levels, while there was no significant difference in the levels in the cases of trisomy 13, balanced translocations, and sex chromosome abnormalities. Maternal serum hCG alone is a better indicator of Down's syndrome pregnancies than maternal age or maternal serum alpha-fetoprotein (AFP), either individually or in combination, and provides a further virtually independent measure of risk. On the basis of our findings, screening for Down's syndrome using hCG and AFP results combined with maternal age risks is predicted to result in a higher detection rate (57 per cent) for a lower false-positive rate (5.0 per cent) than would be attainable by combined AFP and age screening (37 per cent detection at a 6.6 per cent false-positive rate).

Chorionic Gonadotropin↗
PubMed1991

Estimating the risk of a fetal autosomal trisomy at mid-trimester using maternal serum alpha-fetoprotein and age: a retrospective study of 142 pregnancies.

Risks appropriate for mid-trimester prenatal screening for autosomal trisomies have been estimated from a combination of maternal age and maternal serum (MS) alpha-fetoprotein (AFP) levels at 16-20 weeks gestation. Published data on the frequency of Down's syndrome births relative to maternal age were modified to include the additional age-related frequency of trisomy 18 and trisomy 13 cases to provide an overall risk for an autosomal trisomy at mid-trimester. MSAFP results from a retrospective study of 142 affected (114 trisomy 21, 19 trisomy 18, and 9 trisomy 13) and 113,000 unaffected pregnancies were converted to multiples of the appropriate gestational median (MOM). The AFP levels in the autosomal trisomy pregnancies were found to be significantly reduced at 0.72 MOM of the unaffected pregnancies. Risks (likelihood ratios) were derived from the overlapping log Gaussian distributions for affected and unaffected pregnancies and combined with maternal age risks to give the overall odds of an affected pregnancy. A mid-trimester cut-off risk of 1:280 gave an estimated 37 per cent detection rate for autosomal trisomies in the west of Scotland population for a follow-up (false-positive) rate of 6.6 per cent. These figures compare with a 30 per cent detection and 6.7 per cent false-positive rate if age 35 years and over is used as the sole criterion for selection of at-risk pregnancies.

Adolescent↗
PubMed1990

Trisomy 20q caused by der (X)t(X;20)(q28;q11.2).

A first case of "pure" trisomy 20q (q11.2-qter) is described in a female child with minor anomalies and developmental delay. This resulted from the inheritance, from a carrier mother, of an abnormal X chromosome: der (X)t(X;20)(q28;q11.2). Involvement of other autosomes has complicated the interpretation of the phenotypic effect of trisomy 20q in previously published case reports. Red cell gene dosage studies using adenosine deaminase (ADA) have confirmed that the proposita is trisomic for 20q. Taken together with RBG staining studies, these results suggest that there is incomplete inactivation, if any, of the autosomal portion of the consistently late-replicating abnormal X. Unexpectedly, ADA gene dosage results in the carrier mother showed a level of gene expression about half that of normal controls.

Chromosomes, Human, Pair 20↗
PubMed1976

Localisation of the human ABO: Np-1: AK-1 linkage group by regional assignment of AK-1 to 9q34.

Quantitative red cell adenylate kinase (AK-1) assay has been used in 8 patients with partial duplication or deletion of chromosome 9 in an attempt to find the precise intrachromosomal location of the structural gene locus. All regions of chromosome 9 are represented in abnormal dosage in at least one patient. A 43% increase in AK-1 activity was found to be associated with duplication of the terminal band of the long arm of chromosome 9. Duplication of all other parts of chromosome 9 were associated with normal enzyme activity. These findings not only confirm the assignment of the AK-1 locus to chromosome 9 made previously in somatic cell hybrids, but suggest a more precise assignment to region 9q33 leads to qter. This places the ABO:Np-1:AK-1 linkage group at the distal end of the long arm of chromosome 9.

ABO Blood-Group System↗