Are There Two Maternal Age Groups in Down's Syndrome?

1974 ◽  
Vol 124 (582) ◽  
pp. 453-455 ◽  
Author(s):  
P. A. P. Moran
Keyword(s):  
General Population ◽  
Frequency Distribution ◽  
Maternal Age ◽  
Down's Syndrome ◽  
Age Groups ◽  
Down’S Syndrome ◽  
Remarkable Feature ◽  
Complete Survey ◽  
The Mean

Penrose and Smith (1966) have reviewed the literature on Down's syndrome in great detail, and this has been followed by an important recent review by Richards (1973). In Chapters 10 and 11 of Penrose and Smith's book they discuss the remarkable frequency distribution of the ages of mothers of patients, compared with that of the general population at the corresponding place and time, and they summarize the large number of studies made on this subject. The mean age of the mothers is shifted upwards by amounts which vary in different countries from about 6 to 8 years. The remarkable feature, however, is that there appear to be two bumps in the curve. These are usually (but not always) not large enough to make the curve bimodal, and J. B. S. Haldane therefore coined the term ‘bitangentiality’ for this phenomenon, which appears in most published studies and in the group of all sample cases (9,441) given by Penrose and Smith, Fig. 76. Collmann and Stoller (1962) make a complete survey of all mongol births in Victoria, Australia, from 1942 to 1957 and here there is a distinct bimodality.

The incidence of Down's syndrome and progress towards its reduction

1988 ◽  
Vol 319 (1194) ◽  
pp. 315-324 ◽  
Keyword(s):  
Maternal Age ◽  
Down's Syndrome ◽  
Age Groups ◽  
Down’S Syndrome ◽  
Close Relation ◽  
High Rate ◽  
Age Group ◽  
Birth Prevalence ◽  
Considerable Impact ◽  
Exogenous Factors

Down’s syndrome is the most common autosomal aberration and single cause of mental retardation in man. There is a close relation between advanced maternal age and Down’s syndrome. The limitation of family size has made a considerable impact on the incidence of Down’s syndrome. In Denmark in the 1950s, 50% of Down’s syndrome cases were born to mothers over the age of 35. The percentage went down to 25% in the 1970s and was reduced by prenatal diagnosis to 8 % in the 1980s. For the period 1980-85 we followed the birth prevalence closely for the different maternal age groups. The birth prevalence was lowered for the age group over 35, but there was a steady rise for the age groups below 35. Early diagnosis, high rate of survival of light-for-date babies and babies with congenital heart defect, and, possibly, exogenous factors working on gametogenesis might be an explanation. To achieve a reduction in incidence, maternal x-fetoprotein (AFP)-serum screening for low values may be a possibility. So far, avoidance, but not primary prevention, of Down’s syndrome is available.

Total Body Mass Centroid and Segmental Mass Centroid Locations Found in Down’s Syndrome Individuals

1984 ◽  
Vol 1 (3) ◽  
pp. 221-229
Author(s):  
Karen P. DePauw
Keyword(s):  
Center Of Mass ◽  
Down's Syndrome ◽  
Age Groups ◽  
Down’S Syndrome ◽  
Adult Males ◽  
Total Body Mass ◽  
Body Center ◽  
The Mean ◽  
Total Body ◽  
Centers Of Mass

This study was undertaken to investigate the total body and segmental centers of mass of individuals with Down’s syndrome. The 40 subjects were divided equally by gender into the following age groups: (a) ages 6 to 10, (b) ages 11 to 18, (c) adult females, and (d) adult males. Data on mass centroid locations were collected through a photogrammetric technique. Frontal and right sagittal-view slide photographs on each subject were digitized and the data logged into a computer program. The program calculated the segmental mass centroid locations and total body center of mass. Differences in total body and segmental center of mass locations were found between individuals with Down’s syndrome (DS) and nonhandicapped individuals. Analysis of the data on the DS children indicated that the mean center of mass location for the total body was within the range reported for nonhandicapped children. The adult DS male and female subjects were found to have a lower total body center of mass when compared to existing data on nonhandicapped adults. It was also found that the segmental mass centroid locations for the head and trunk segment of DS subjects were consistently lower than those found in nonhandicapped individuals. This finding points to an overall lowering of the center of mass found with DS subjects.

THE ROLE OF CHROMOSOME TRANSLOCATION IN THE RECURRENCE RISK OF DOWN'S SYNDROME

PEDIATRICS ◽  
1965 ◽  
Vol 35 (3) ◽  
pp. 463-469
Author(s):  
C. David Petersen ◽  
Luigi Luzzatti
Keyword(s):  
General Population ◽  
Maternal Age ◽  
Down's Syndrome ◽  
Down’S Syndrome ◽  
Recurrence Risk ◽  
Chromosome Translocation ◽  
Young Mother ◽  
Affected Child ◽  
Usual Type ◽  
Hereditary Factors

Increasing knowledge of the chromosomal pattern of patients with Down's syndrome has helped in elucidating the possible hereditary factors present in this condition. The pattern of transmission of the translocation type from a parental carrier to the offspring is fairly well defined. There is still a question concerning possible hereditary factors in the transmission of the more usual type, characterized by simple trisomy of chromosome No. 21. While the over-all incidence of Down's syndrome increases with maternal age, the chance for a second affected child is greater in the younger maternal age group. The present study has been undertaken to evaluate: (1) the frequency of inherited translocation among affected children born to younger mothers, and (2) the significance of translocation in the increased recurrence risk of the young mother. A total of 227 index patients with Down's syndrome, born to mothers age 15 to 29 years, was collected. Of these, 42 were studied in our laboratory and the others collected from the literature. In this group, the incidence of the usual type of trisomy 21 was 92.1% and the incidence of the translocation type 7.9%. In 1.8% of the patients the mother carried a D/21 translocation. On the basis of the frequency of maternal D/21 translocation in this group and the expected ratio of affected offspring born in the general population a recurrence risk has been calculated for all mothers with an affected child purely on the chance they may carry a D/21 translocation. This calculated recurrence risk decreases with increasing maternal age and never approaches the figures of the observed total recurrence risk available in the literature. After age 35, data in this study concur with those in the literature, failing to demonstate an increased recurrence risk over the general population. Though the data are by necessity small, the figures in this study tend to suggest that only a part of the increased recurrence risk of the young mother is due to the possibility she may carry a translocation. There are undoubtedly other still ill-defined factors that may predispose to a recurrence of affected children in these mothers. These factors are discussed but more data are necessary for accurate genetic counseling.

Incidence of Down's Syndrome by Maternal Age of Asian Population

2020 ◽  
Author(s):  
Song Yi ◽  
Jieping Song ◽  
Feng Liu ◽  
Xu Liu ◽  
Chengcheng Zhang ◽  
...  
Keyword(s):  
Maternal Age ◽  
Down's Syndrome ◽  
Asian Population ◽  
Down’S Syndrome

A study of maternal age in Down's syndrome

1966 ◽  
Vol 29 (3) ◽  
pp. 271-276 ◽  
Author(s):  
HANS OLOF ÅKESSON ◽  
H. HANS FORSSMAN
Keyword(s):  
Maternal Age ◽  
Down's Syndrome ◽  
Down’S Syndrome
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