Evaluation of Chromosomal Analyses done on the Parents with Chromosomal Anomalous Children and Recurrent Abortion

PURPOSE: To gather reference data for better genetic counseling, we have evaluated the outcomes of chromosomal analyses performed on the parents with chromosomal anomalous children and recurrent abortion in this hospital for the last 20 years. METHODS: Subjected to study were 108 parents (50 fathers & 58 mothers) who had children with Down syndrome, other chromosomal and congenital anomalies, and those who had experienced frequent miscarriages from March 1974 through August 1994. The Moorhead's method with G banding technique was used. RESULTS: 1) Of those 108 parents studied, 52 (48.1%) had Down babies, 27 (25.0%) had frequent miscarriages or stillbirths, 22 (20.4%) had children with congenital anomalies, and 7 (6.5%) had other chromosomal anomalies. 2) Abnormal karyotypes were detected in 9 (8.3%): 6 among 52 parents with Down babies (11.5%), 1 out of 7 parents whose children had other chromosomal abnormalities (14.2%), and 2 from 27 who had experienced miscarriages (7.4%). 3) Abnormal karyotypes of the parents who had Down babies were: balanced 14q21q translocations in 2 mothers and 1 father, balanced 21q21q translocation in a carrier mother who looked like Down's, and 14q+ in a normal-looking father. Among the parents having babies with anomalies other than Down's, one mother who gave births to 2 babies, one with balanced and the other with unbalanced translocation, was found to carry t(12;13) balanced translocation. Two women who had experienced frequent miscarriages were found to have balanced 14q21q translocation in one and XXq- in the other. 4) Abnormal karyotypes detected in 6 among those 52 parents with Down babies were: 3 out of 38 whose babies had 21-trisomy (7.9%), 2 among 8 parents having babies with 14q21q translocation (25%), and one from 6 parents whose babies had 21q21q translocation (16.7%). 5) Out of 375 Down children, 3 had Down sibling, with the overall recurrence rate of 0.8%, and 2 out of 6 parents of those 3 families were revealed to be balanced translocation carriers. CONCLUSIONS: The high incidence of carrying chromosomal anomaly among the parents having chromosomal anomalous children, but otherwise normal-looking, advocates it essential to have the parents analyzed for their chromosomal make-ups in order to provide better genetic counseling to those who gave birth to a baby with chromosomal abnormality or experienced frequent miscarriages.

Changes in Maternal Age and the Incidence of Down Syndrome

PURPOSE: The incidence of Down syndrome, the most common chromosoaml anomaly, increases with the advanced maternal age. Recently, however, the incidence of Down symdrome was reported to have decreased with wide acceptance of prenatal diagnosis and planned parenthood, prompting us to re-evaluate the incidence of Down syndrome in relation to changes in maternal age. METHODS: Subjected to study were 296 Down cases: 26 newborn Down's among the 58,479 deliveries undergone in our hospital (KCH) during the period over 2 decades from April 1974 through December 1994; and 270 cases, whose maternal age at delivery could be traced with certainty, among 366 Down cases confirmed by genetic counseling. The observation period was divided into three: Period I, before 1979 (n=66); Period II, from 1980 to 1989 (n=127); and Period III, after 1990 (n=103). RESULTS: 1) The change in maternal age at delivery Of total 58,479 deliveries, 0.5% were born to mothers younger than 20 years, 21.3% were aged 20-25 years; 57.7% (33,722) were aged 26-30 years; 16.9% fell between 30-35 years; and 3.6% were above 35 years. Deliveries of old mothers (>35 ys) were 4.9% in Period I, which significantly decreased to 2.8% in Period II, increased again to 4.1% in Period III. 2) Changes in Down incidence among those delivered in KCH Overall Down incidence among those delivered in KCH was 0.44/1000 (26/58,479); however, it was 0.93/1000 in Period I, 0.16 in II, significantly lower; and 0.59/1000 in Period III. Of the 26 Downs born in KCH 18 were born to mothers younger than 35 years (0.03%), whereas 8 were born to mothers older than 35 years (0.8%). The Down incidence among mothers younger than 35 years did not significantly differ among the periods, while for the mothers aged over 35 years it decreased from 1.0% (6/576) in Period I to 0% (0/825) in Period II, and back to 0.3% (2/698) in Period III, indicating that Down incidence among old mothers significantly decreased recently, compared with the early period. 3) Changes in maternal age and Down incidence among those confirmed by genetic counseling. Of those 270 Down cases, 226 were born to mothers younger than 35 years, whereas 44 were delivered by old mothers aged above 36 years. Old mothers had Down babies in 23.6% (13/55) in Period I, but it significantly decreased to 11.5% (14/122) in Period II, but it recovered to 18.2% (17/93) in Period III. 4) Relationship between karyotype pattern and maternal age Of total 296 Down cases 260 (87.8%) had typical pattern of 21-trisomy, 32 (10.8%) translocation, 4 (1.4%) mosaicism. Those with typical trisomy had mean age (+/-S.D.) of 30.3 (+/-6.0) year and those with mosaicism 30.8 (+/-6.2) year, whereas those with translocation were significantly younger with the mean age of 26.6 (+/-2.5) year. CONCLUSIONS: During the last 2 decades, the deliveries by old mothers tended to decrease, and also the overall incidence of Down syndrome has significantly decreased, especially among those born to mothers older than 35 years. Recently, however, maternal age tends to increase for various reasons, necessitating due emphasis on prenatal diagnosis.

Clinical Characteristics of Patients with Tumer Syndrome according to Karyotypic Differences

No abstract available.