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PubMed1999

A high-sensitivity alternative to "routine" genetic amniocentesis: multiple urinary analytes, nuchal thickness, and age.

OBJECTIVE: Our purpose was to evaluate the Down syndrome screening efficiency of a new algorithm consisting of multiple urinary biochemical and ultrasound markers for use in high-risk groups such as women of advanced maternal age. STUDY DESIGN: The urinary beta-core fragment of human chorionic gonadotropin (beta-core fragment) and total urinary estriol, along with fetal nuchal thickness, were measured prospectively in pregnant women who were undergoing genetic amniocentesis at midtrimester (15 to 24 weeks). The most common indication for amniocentesis was advanced maternal age (90.2%). An analyte ratio (beta-core fragment/total estriol ratio) was developed. The values were expressed as multiples of the normal median. An increase in the observed nuchal thickness (delta nuchal thickness) above that expected on the basis of the biparietal diameter was calculated. On the basis of the mean and standard deviations of the urinary analyte ratio in normal fetuses and also Down syndrome, we calculated individual Down syndrome likelihood ratios for each of the two parameters, using gaussian analysis. The product of the likelihood ratios, based on delta nuchal thickness and urinary beta-core fragment-total estriol values times the maternal age-related risk, gave the overall Down syndrome risk. The screening efficiency of our algorithm at various risk thresholds was determined. RESULTS: There were 13 (2.8%) cases of Down syndrome in a total study population of 457. At a risk threshold of >1 in 70, the sensitivity was 92.3% for a false-positive rate of 4.5%. Corresponding values at a risk threshold of >1 in 78 were a sensitivity of 100% with a false-positive rate of 5.2%. CONCLUSION: By combining urinary analyte, nuchal thickness, and maternal age data, we achieved a high Down syndrome detection rate with a low false-positive rate. This algorithm would be attractive as an alternative to "routine" amniocentesis based solely on advanced maternal age. The potential benefits of this protocol could include a significant reduction in the rate of amniocentesis, along with substantial savings in medical expenditures.

Adult↗
PubMedDate not supplied

The graying of the obstetric population: implications for the older mother.

OBJECTIVE: To review the literature on the relationship between advanced maternal age and pregnancy outcomes and to discuss social trends in childbearing. DATA SOURCES: Computerized searches on CINAHL, MEDLINE, National Institutes of Health, and published birth statistics. Keywords used in this search were the following: advanced maternal age, pregnancy outcomes for older primiparae and older mothers, and pregnancy risks. STUDY SELECTION: Relevant articles published between 1978 and 2001 were reviewed. DATA EXTRACTION: Data were extracted and organized under the following headings: childbearing trends in developed countries, maternal morbidity for older mothers, preeclampsia, preterm delivery, operative and assisted delivery, and infant mortality and morbidity. DATA SYNTHESIS: The existing literature is concentrated on the medical aspects of the risks associated with childbearing at an advanced maternal age. Few systematic investigations have been undertaken of healthy older mothers, an increasingly common obstetric population. CONCLUSIONS: Lifestyle influences, such as weight, general health, and smoking habits in older mothers, have not been addressed. Little is known about the actual risks of pregnancy complications for healthy older mothers. No clear guidelines exist to direct the obstetric and nursing care of the healthy older mother.

Adult↗
PubMed1998

Preimplantation diagnosis of common aneuploidies by the first- and second-polar body FISH analysis.

PURPOSE: A low pregnancy rate in in vitro fertilization (IVF) patients of advanced maternal age may be caused by aneuploidies originating from non disjunction in the first or second meiotic divisions. We introduced genetic testing of oocytes by sampling and fluorescent in situ hybridization (FISH) analysis of the first and second polar bodies, to avoid fertilization and transfer of aneuploid oocytes in IVF patients of advanced maternal age. METHODS: Three hundred and sixty-three IVF patients 34 years and older participated in the study. Using micromanipulation procedures, the first and second polar bodies were removed following their extrusion from the oocytes and studied by FISH, using probes specific for chromosomes 13, 18, and 21 to detect oocytes with common aneuploidies. RESULTS: Of a total of 538 IVF cycles, 3250 oocytes were available for FISH analysis, with conclusive FISH results in 2742 oocytes (84.3%). As many as 1102 (40%) of oocytes were predicted to be aneuploid and not transferred. Of 1640 embryos predicted to be normal, 1145 were transferred in 467 treatment cycles, resulting in 107 pregnancies (23%), from which 67 healthy children have been born, 32 pregnancies spontaneously aborted, and 15 pregnancies are ongoing after being confirmed normal by prenatal diagnosis. CONCLUSIONS: Preimplantation diagnosis by first- and second-polar body FISH analysis allows us to avoid the age-related risk of common aneuploidies in IVF patients of advanced maternal age.

Aneuploidy↗
PubMed1999

Quality of embryo does not affect the implantation rate of IVF-ET in infertile women with antisperm antibody.

OBJECTIVE: To determine whether low quality score of embryos and advanced maternal age affect the implantation rate in infertile women with sperm-immobilizing antibody. DESIGN: A retrospective study. SETTING: The IVF Unit of the Department of Obstetrics and Gynecology at Tokushima University Hospital. PATIENT(S): Four infertile groups were studied: 20 women with sperm-immobilizing antibodies; 169 with tubal; 129 with male factor; and 72 with unexplained etiology. INTERVENTION(S): All women were hyperstimulated with GnRH analogue and scheduled ovarian stimulation with FSH and hMG for oocyte retrieval. MAIN OUTCOME MEASURE(S): Relationship of quality of transferred embryos, implantation rate and maternal age among four groups of infertile couples. RESULT(S): In the antisperm group, the fertilization rate (57.6%) and mean (+/- SD) score of transferred embryos (5.4+/-1.9) were significantly lower than those in the tubal group (72.4% and 6.2+/-1.9, respectively). However, the implantation rate in the antisperm group (23.6%) was significantly higher than those in other three groups (tubal, 8.6%; male factor, 9.5%; unexplained, 7.6%). With advancing maternal age, the implantation rate decreased in the three comparative groups. In contrast, the implantation rate in the antisperm group did not decrease with advancing maternal age. CONCLUSION(S): Women with antisperm antibodies have several disadvantages to overcome in order to achieve successful IVF-ET, such as a low fertilization rate and poor quality of transferred embryos. However, a high implantation rate was observed in this group, even in women at advanced age. The occurrence of a cellular or humoral immune reaction against sperm may augment the uterine receptivity for the implantation of fertilized ova or blastocyst.

Adult↗
PubMedDate not supplied

Effects of mid-trimester induced abortion on the subsequent pregnancy.

The outcome of the pregnancy following (a) a mid-trimester termination of pregnancy (TOP) for fetal neural tube defect (NTD) (77 women = group 1); (b) mid-trimester TOP for fetal Down's syndrome (13 women = group 2); (c) delivery of a baby with NTD (119 women = group 3) was studied. The prenatal fetal loss was relatively high in all groups. In group 1 it was similar to that found in other studies after first trimester TOP, in group 2 it was associated with advanced maternal age and the unexpected finding in group 3 was not attributable to advanced maternal age. It is suggested that a previous NTD per se might increase the risk of fetal loss in the next pregnancy. A previous mid-trimester TOP for NTD was not associated with an increase in premature labour, small for dates babies or congenital abnormality in the next pregnancy, but there was a slight increase in the number of babies weighing less than 2500 g.

Abortion, Induced↗
PubMed2006

Relationship of recombination patterns and maternal age among non-disjoined chromosomes 21.

Advancing maternal age has long been identified as the primary risk factor for human chromosome trisomy. More recently, altered patterns of meiotic recombination have been found to be associated with non-disjunction. We have used trisomy 21 as a model for human non-disjunction that occurs during the formation of oocytes to understand the role of maternal age and recombination. Patterns of recombination that increase the risk for non-disjunction of chromosome 21 include absence of any exchange, an exchange near the centromere or a single, telomeric exchange. Our recent work has shown that different susceptibility patterns are associated with the origin of the meiotic error and maternal age. For MI (meiosis I) errors, the proportion of oocytes with susceptible recombination patterns is highest among young mothers and decreases significantly in the oldest age group. In fact, the pattern of exchanges among the oldest age group mimics the pattern observed among normally disjoining chromosomes 21. These results suggest that oocytes of younger women, with functional meiotic apparatus and/or robust ovarian environment, are able to properly resolve all but the most susceptible exchange patterns. As women age, however, meiotic mechanisms erode, making it difficult to resolve even stable exchange events. Interestingly, our preliminary recombination results on MII errors reveal the opposite relationship with maternal age: susceptible pericentromeric exchanges occur most often in the older age group compared with the younger age group. If confirmed, we will have further evidence for multiple risk factors for non-disjunction that act at different times in the meiotic process.

Chromosomes, Human, Pair 21↗
PubMed1999

Indication-specific accuracy of second-trimester genetic ultrasonography for the detection of trisomy 21.

OBJECTIVE: The object of this study was to determine whether there are any clinically significant indication-specific variations in the accuracy of second-trimester genetic ultrasonography and to provide a risk adjustment for fetal trisomy 21 according to the results of genetic ultrasonography. STUDY DESIGN: From November 1, 1992, to September 30, 1998, a second-trimester genetic sonogram was offered to all pregnant women who were at an increased risk for fetal trisomy 21 (>/=1:274) because of either advanced maternal age (>/=35 years) or abnormal serum biochemical profile or both of these. Outcome information included the results of genetic amniocentesis if performed and the results of pediatric assessment and follow-up after birth. In determining diagnostic accuracy of the genetic sonogram the presence of >/=1 abnormal ultrasonographic marker was considered an abnormal test result. RESULTS: A total of 1835 fetuses with known outcomes underwent genetic ultrasonography between 15 and 24 weeks' gestation; of these 1792 had normal results, 34 had trisomy 21, and 9 had other chromosomal abnormalities. The likelihood of fetal trisomy 21 was reduced by 80% after a normal result of genetic ultrasonography. The overall sensitivity, specificity, and positive and negative predictive values of genetic ultrasonography for the detection of trisomy 21 were 82%, 91%, 15%, and 99.6%, respectively. There were no significant indication-specific variations in the accuracy of second-trimester ultrasonography. The sensitivity for the detection of fetal trisomy 21 ranged from 80% among women with advanced maternal age to 100% among women with both an abnormal biochemical profile and advanced maternal age. CONCLUSIONS: The likelihood of fetal trisomy 21 risk was reduced 80% after a normal result of genetic ultrasonography. In addition there were no significant indication-specific variations in the detection rate of genetic ultrasonography.

Adolescent↗
PubMed1982

Alzheimer's disease and maternal age.

Findings from several studies suggest a relationship between Alzheimer's disease and Down's syndrome. It has long been known that advanced maternal age is a risk factor for Down's syndrome, and that mothers who give birth to a child with this syndrome have characteristics consistent with accelerated aging. Little is known about risk factors for Alzheimer's disease, other than age. In this study, documentation is supplied for a hypothesis concerning a relationship between Alzheimer's disease and advanced maternal age.

Aged↗
PubMed2003

Prenatal screening for Down syndrome in England and Wales and population-based birth outcomes.

OBJECTIVE: Whether the introduction of antenatal screening for Down syndrome in England and Wales with serum biochemistry or ultrasound has led to improvements in patient outcomes is unknown. The purpose of this study was to relate pregnancy outcomes to the dominant method used for prenatal Down syndrome screening. STUDY DESIGN: For the years 1989 through 1999, England and Wales were divided into geographically defined areas where specific hospitals, health authorities, and cytogenetic laboratories provided maternity care for well-defined populations. For each year from 1989 through 1999, the dominant Down syndrome screening method that was used in each area was determined. Outcomes for area-years that used serum biochemistry or ultrasound (first or second trimester) were compared with area-years that used advanced maternal age as the dominant screening method. The percent of Down syndrome cases that were diagnosed prenatally (effectiveness) and the number of invasive prenatal tests that were performed to diagnose each Down syndrome case prenatally (efficiency) were compared. RESULTS: There were 5,980,519 births and 335,184 referrals for prenatal karyotyping (amniocentesis and chorionic villus sampling) that occurred in the area-years studied, of which 12,047 pregnancies were diagnosed as Down syndrome; 5393 cases of Down syndrome (45%) were diagnosed prenatally. Invasive testing increased from 4.4% of pregnancies in 1989 to 6.4% in 1997 and declined slightly in 1999 (5.8%). Prenatal diagnosis of Down syndrome cases rose from 28% in 1989 to 53% in 1999, and the number of invasive tests that were performed to diagnose each Down syndrome case fell from 89.7 to 47.7 (P [for trend]<.0001). Areas with serum or ultrasound as the dominant screening method detected 50% more Down syndrome cases in prenatally (52% and 53% vs 36%; P<.0001) and performed fewer invasive procedures to diagnose each Down syndrome case (60.7 and 52.0 vs 88.0; P<.0001) compared with areas in which advanced maternal age screening was dominant, despite serving populations with similar mean/median maternal ages. CONCLUSION: In clinical practice, screening programs for Down syndrome that were based on maternal serum biochemistry or ultrasound were more effective and efficient than the screening programs that used advanced maternal age alone.

Amniocentesis↗
PubMed1994

Chromosomal abnormalities detected after an abnormal ultrasound in pregnancy.

Improvements in ultrasound technology have resulted in an increasing number of requests for prenatal chromosome testing because of fetal abnormalities detected in utero. Between January 1990--January 1991, 388 tissue samples were referred to our laboratory for cytogenetic analysis, of which 202 were amniotic fluids samples, 157 chorionic villus biopsies and 29 fetal blood specimens. Of these 54 were referred for fetal abnormalities detected prenatally on high resolution ultrasound. Chromosomal analysis was successful in 50 cases, and included 6 (12%) chromosomally abnormal fetuses: 2 trisomy 21, 2 trisomy 18, one 45,X and one unbalanced translocation. The maternal age for three of the four cases of autosomal trisomy were below 35 years (the cut-off for amniocentesis for advanced maternal age). In contrast, 273 prenatal chromosome studies performed for advanced maternal age (AMA) produced only 4 (1.5%) chromosomally abnormal fetuses. These abnormalities detected on ultrasound indicate a significant population of fetal chromosomal aberrations which would otherwise not be detected prenatally.

Adult↗
PubMed1993

Pregnancy in women aged 40 and older.

Counseling patients about pregnancy at advanced maternal age is a difficult process. This is true both because our knowledge of the attendant risks is incomplete and still evolving, and because of the difficulties of assigning risks and addressing counterbalancing benefits for individual patients. There are a number of social and personal considerations involved in a decision to become a parent after the age of 40. Generally, older parents tend to be more mature, to be in stable and healthy marriages, and to have more financial and family resources to assist with the process of child rearing. Parents in their fifth decade, however, may complain of having less energy to devote to young children or may be at a stage in their careers in which they have less time for family participation than when they were younger. Also, grandparents, who can play a critical role in early childhood development, often have become too old to participate in that role or have died. All of these issues must be considered by parents contemplating late childbearing. A great deal has been written, much of it positive, even enthusiastic, about the quality of pregnancy and childbirth among older women. Nevertheless, much of the literature is difficult to interpret because of problems in controlling for confounding variables. In addition, much of the focus on so-called older women has been on those older than 35 years. In fact, the great majority of the medical literature concerning late childbearing relates to women between the ages of 35 and 40. The data that directly concern women in their fifth decade suggest that risks that began to accelerate after the age of 35 become considerably greater and increase more rapidly after the age of 40. Obviously, couples must decide what risks they are willing to accept and how these potential risks might be countervailed by the presumed advantages of parenthood relatively late in the reproductive years. There is convincing evidence to show that fecundity is decreased with advancing maternal age, and various forms of early pregnancy loss are increased. Thus, to delay childbearing results in a significant decrease in the likelihood of becoming pregnant or carrying a pregnancy to term. The possibility of genetic disorders is, as has been discussed previously, relatively easy to quantitate, and most age-related anomalies are amenable to prenatal diagnosis. It seems clear that women with underlying medical diseases, particularly hypertension and diabetes mellitus, contribute heavily to the excess morbidity and mortality associated with late childbearing.(ABSTRACT TRUNCATED AT 400 WORDS)

Female↗
PubMed1996

Polar body diagnosis of common aneuploidies by FISH.

PURPOSE: The purpose of this work was to investigate the reliability and accuracy of polar body analysis for preimplantation diagnosis of common aneuploidies in IVF patients of advanced maternal age. DESIGN: We have previously introduced polar body analysis as an approach for nondestractive evaluation of the genotype of human oocytes. The method has recently been applied in a clinical trial involving 45 infertile patients, demonstrating the feasibility of preconception diagnosis of common aneuploidies by fluorescent in situ hybridization (FISH). The present paper describes the experience of polar body diagnosis in 135 IVF patients (161 cycles) of advanced maternal age. RESULTS: FISH results of the first and/or second polar bodies were available in 648 (72.4%) of 895 biopsied oocytes subjected to FISH analysis. Of 648 oocytes with FISH results, 208 demonstrated chromosomal abnormalities. Of 440 oocytes predicted to be free from monosomy or trisomy of chromosomes X, 18, and/or 13/21, 314 were normally fertilized, cleaved, and transferred in 122 treatment cycles, resulting in 6 healthy deliveries and 12 ongoing pregnancies following confirmation of the polar body diagnosis by CVS or amniocentesis. CONCLUSIONS: The method may be useful for detection of oocytes with common chromosomal trisomies in IVF patients of advanced maternal age.

Abortion, Spontaneous↗
PubMed1999

Laser-assisted hatching in assisted reproduction.

AIM: The use of a 1.48 um diode laser for assisted hatching was investigated in animal experimentation. Laser assisted hatching was offered to patients with advanced maternal age to evaluate a possible benefit. METHODS: Using the Fertilase(r) system we investigated the impact of openings with different size in the zona of mouse embryos on the hatching process, as well as that of two openings. Laser-drilling was performed at the blastocyst stage to look for differences in timing and efficacy of hatching. The possible benefit of assisted hatching was studied in 24 couples with advanced maternal age (38.8+2.1 years) and compared to a control group (37.8+2.5 years) treated in the same time period but without assisted hatching. RESULTS: A certain diameter of a laser drilled opening in the zona pellucida is necessary for efficient hatching. When two openings are present in the zona, the embryo will use both openings for hatching and subsequently become trapped. Laser-drilling at th e expanded blastocyst stage causes an immediate collapse of treated blastocysts and the onset of hatching is retarded. Assisted hatching in 24 patients with advanced maternal age resulted in a significant increase (p<0.01) in the implantation rate when compared to 24 untreated patients. CONCLUSION: The use of a 1.48 microm diode laser to drill an opening into the zona pellucida provides a good alternate to conventionally applied techniques. The procedure is efficient and safe as long as it is applied properly. In a human in vitro fertilization program, selected patients will have a benefit form assisted hatching.

Adult↗
PubMed2007

Incidence of Down syndrome in Dubai, UAE.

OBJECTIVE: To describe incidence of Down syndrome in Dubai, United Arab Emirates (UAE). SUBJECTS AND METHODS: A total of 63,398 newborn babies in Dubai (24,250 UAE nationals and 39,148 non-UAE) during a 5-year period of 1999-2003 were routinely examined by experienced nurses, neonatologists, pediatricians and/or general practitioners for symptoms of Down syndrome. Those suspected with Down syndrome were referred to the cytogenetic laboratory for karyotyping. RESULTS: A total of 141 cases were confirmed cytogenetically as Down syndrome. Of these, 139 were trisomy 21 and of the remaining 2, 1 was a translocation and the other a mosaic. Theoverall incidence of Down syndrome in Dubai was 1/449 live births (2.2 per 1,000); 1/319 live births (3.13 per 1,000) among UAE nationals and 1/602 live births (1.66 per 1,000) among non-UAE nationals. The mean maternal age of UAE national mothers was 33.48 +/- 8.08, with 41.66% of the mothers being in the advanced maternal age group (>35 years). The higher incidence of Down syndrome among UAE nationals is comparable to incidences reported for other Arab populations in the Middle Eastern region. Advanced maternal age, with mothers bearing children until their 50s and higher parity, appear to be the major contributing factors for the increased incidence. CONCLUSION: The study indicates the need to provide efficient genetic counseling and to introduce an effective antenatal screening program and prenatal diagnostic services to reduce the psychological and genetic burden on the families and community.

Adolescent↗
PubMed2002

Down syndrome risk estimation after normal genetic sonography.

OBJECTIVE: The objective of this study was to determine whether there are any indication-specific variations in risk reduction for fetal Down syndrome after a normal genetic sonogram. STUDY DESIGN: A second-trimester genetic sonogram was offered to all pregnant women who were at increased risk for fetal Down syndrome (>/=1:274) because of either advanced maternal age (>/=35 years), an abnormal triple screen, or both. Outcome information included the results of genetic amniocentesis (if performed), the results of pediatric assessment, and follow-up after birth. Normal genetic sonography was defined as the absence of all ultrasound aneuploidy markers. RESULTS: The overall prevalence of fetal Down syndrome in the tested population was 1.41% (53/3,753 pregnancies); however, in the presence of normal genetic sonography, the overall prevalence of fetal Down syndrome was 0.21% (7/3,291 pregnancies). The overall risk reduction for fetal Down syndrome in the presence of normal genetic sonography was 6.64-fold (95% CI, 3.01-14.62); the overall negative likelihood ratio was 0.15 (95% CI, 0.07-0.33). In the presence of normal genetic sonography, the risk for fetal Down syndrome was reduced by 83% in patients with advanced maternal age, 88% in patients with abnormal triple screen, 89% in patients with abnormal triple screen who were <35 years old, and 84% in patients who had both abnormal triple screen and advanced maternal age. CONCLUSION: There were no significant variations in the risk reduction for fetal Down syndrome in the presence of normal genetic sonography. Regardless of the indication for testing, the likelihood for fetal Down syndrome was reduced by 83% to 89%. This information will be useful in counseling pregnant women who are at high risk for fetal Down syndrome and who prefer to undergo genetic sonography before deciding about genetic amniocentesis.

Adolescent↗
PubMed1991

Association of decreased paternal age and late-onset Alzheimer's disease. An example of genetic imprinting?

Several studies have identified advanced maternal age as a risk factor for Alzheimer's disease. This study evaluated maternal and paternal age at birth of 237 patients with Alzheimer's disease, each of whom was matched to five control subjects based on sex, year of birth, survival age, and location of residence. It was found that decreased paternal age substantially increased the susceptibility to the common form of Alzheimer's disease that occurs after the age of 67 years, whereas advanced maternal age had a negligible effect on risk of Alzheimer's disease. The higher incidence of late-onset Alzheimer's disease among persons born to younger fathers is consistent with a genetic imprinting mechanism involving DNA methylation. The proposed model postulates a role for environmental agents in the pathogenesis of Alzheimer's disease and accounts for families that show an aggregation of cases but no apparent pattern of inheritance.

Adult↗
PubMed2003

Genetic counseling and prenatal diagnosis in India--experience at Sir Ganga Ram Hospital.

UNLABELLED: The experiences in genetic counseling and prenatal diagnosis at a tertiary genetic center in India are described. Of 3500 subjects provided genetic counseling 28.7% were for prenatal diagnosis, 13.7% for mental retardation +/- malformations, 11.5% for thalassemia, hemophilia and leukemia, 8.5% for neural tube defects and other malformations, and 8% for muscle dystrophy and spinal muscle atrophy. Chromosomal studies in blood (n = 5459) were for recurrent abortions (57.8%), delayed milestones (14.7%), malformations (11%), and infertility and amenorrhea (10.2%). Indications for amniotic fluid studies (n = 835) were advanced maternal age (35.7%), high risk result on triple test (21.3%), previous child with trisomy 21 (21.3%) and abnormalities seen on ultrasound (11.1%). Molecular studies were mostly for thalassemia (843, 24.3%), Duchenne muscular dystrophy (443, 12.5%), fragile X syndrome (367, 10.3%), spinal muscular atrophy (315, 8.9%), thrombophilia profile (233, 6.6%), triplet repeat disorders-spinocerebellar ataxias, Huntington disease and Friedreich ataxia-162 (4.6%), cystic fibrosis 140 (3.9%) and mitochondrial disorders 101 (2.9%). Other disorders for which molecular diagnosis was done were intrauterine infections by PCR on the amniotic fluid, Prader Willi/Angelman syndromes, hemophilia, achondroplasia, congenital adrenal hyperplasia, and Apert syndrome etc. In biochemical studies triple marker tests were the most common (3239), followed by aminoacid chromatography (774). Among neurolipidosis metachromatic leukodystrophy was the commonest, followed by Krabbe's disease, Tay Sach disease and Gaucher disease. Of the mucopolysacharidoses Hurler syndrome was the commonest, followed by Hunter syndrome. These data are compared with previous studies and a change towards increased prenatal diagnostic tests is observed. The commonest indication for amniocentesis has changed to advanced maternal age. CONCLUSION: Advanced molecular, cytogenetic and biochemical techniques have been a useful addition for genetic counseling and prenatal diagnosis in India.

Chromosome Aberrations↗
PubMedDate not supplied

Chromosomal abnormalities in a series of 6,733 human oocytes in preimplantation diagnosis for age-related aneuploidies.

Most chromosomal abnormalities originate from female meiosis and contribute significantly to pregnancy failures, particularly in women of advanced maternal age. A total of 8,382 oocytes were obtained in 1,297 IVF cycles from patients of advanced maternal age (mean 38.5 years). Following a standard IVF protocol, oocytes were tested following removal and fluorescence in-situ hybridization (FISH) analysis of the first (PB1) and second polar bodies (PB2), using probes specific for chromosomes 13, 16, 18, 21 and 22 (Vysis). FISH results were available in 67,33 (80.3%) oocytes tested, 3,509 (52.1%) of which were aneuploid, with the remaining 3,224 (47.9%) normal oocytes available for transfer. In all, 41.7% of oocytes had meiosis I errors, compared to 35.1% with meiosis II errors. Abnormalities in meiosis I were represented by extra chromatids in 15.4%, missing chromatids in 48.1%, missing chromosomes in 5.9%, extra chromosomes in 0.5%, and complex abnormalities in 30.1%. The proportions of abnormal oocytes with missing or extra chromatids in meiosis II were 36.6 and 41.2% respectively, with the remaining oocytes having complex abnormalities, involving missing or extra chromatids of different chromosomes (22.1%) following meiosis II. Overall, 41.8% oocytes had meiosis I, 30.7% meiosis II, and 27.6% both meiotic division errors. A total of 45.1% of the abnormal oocytes had complex errors, involving the same chromosome in both meiotic divisions (21.5%), or different chromosomes (78.5%), of which 74.8% were with abnormalities of two, and 25.2% with abnormalities of three chromosomes studied. Of 3,224 detected aneuploidy-free zygotes, 2,587 were transferred in 1,100 treatment cycles (2.35 embryos per transfer), resulting in 241 (21.9%) clinical pregnancies and 176 healthy children born, suggesting a positive clinical outcome following aneuploidy testing of oocytes in a group of IVF patients of average age 38.5 years.

Adult↗