Robertsonian translocations: an overview of a 30-year experience in a single tertiary medical center in Taiwan.

BACKGROUND: Advanced maternal age (AMA) is the most frequent indication for amniocentesis in predicting balanced reciprocal translocations, and abnormal ultrasound findings are indications in predicting unbalanced reciprocal translocations; however, to date, no studies have focused on Robertsonian translocations. METHODS: A retrospective review was conducted on 16,749 pregnant women who underwent midtrimester amniocentesis between January 1981 and December 2010. Robertsonian translocations were identified in 39 cases. RESULTS: The percentage of Robertsonian translocations in all amniocentesis cases was 0.23% (39/16,749); 31 were balanced and eight were unbalanced. De novo abnormality occurred in 17 cases, or in 43.6% of all Robertsonian translocations. The two major indications for amniocentesis with a diagnosis of Robertsonian translocations were AMA (41.0%, n = 16) and a parent with abnormal karyotypes (18.0%, n = 7). The highest percentage of Robertsonian translocations was found in parents with abnormal karyotypes (2.8%, 7/252), but neither of the indications were clearly superior for detecting de novo Robertsonian translocations. CONCLUSION: Although AMA is an indication for amniocentesis in approximately two-fifths of cases with Robertsonian translocations, the indication of parent with abnormal karyotypes was more likely to lead to the detection of non-de novo Robertsonian translocations, suggesting that parents with abnormal karyotypes need careful prenatal consultation.

Balanced and unbalanced reciprocal translocation: an overview of a 30-year experience in a single tertiary medical center in Taiwan.

BACKGROUND: Reciprocal translocation is the most common type of translocation; however, there are only a few studies that address the indications for reciprocal translocation in amniocentesis. Here we share our data, based on 30 years' experience in a single tertiary center, to investigate the rates and indications for amniocentesis in cases of reciprocal translocations. METHODS: A retrospective review of 16,749 pregnant women, who underwent midtrimester amniocentesis between January 1981 and December 2010, was conducted. Seventy-four cases of reciprocal translocation were identified. RESULTS: The percentage of reciprocal translocations in all amniocentesis cases was 0.44% (74/16,749); of these 74 cases, 56 were balanced and 18 unbalanced. De novo abnormality occurred in 23 cases, which constituted 31.1% of all reciprocal translocations. The three major indications for amniocentesis with a diagnosis of reciprocal translocation included advanced maternal age (AMA, 52.7%), a parent with an abnormal karyotype (17.6%), and abnormal biochemical markers in the maternal serum (12.2%). For individual types of reciprocal translocations (balanced and unbalanced), except for the presence of abnormal biochemical markers in maternal serum, both AMA and a parent with an abnormal karyotype were primary indications for amniocentesis. However, the highest percentage of reciprocal translocations in all amniocentesis cases was found in cases involving a parent with an abnormal karyotype (5.16%, 13/252). CONCLUSION: Patients with a parent who carries an abnormal karyotype should be encouraged to undergo amniocentesis in prenatal consultation, since the risk of a diagnosis of reciprocal translocation can be particularly high.

An overview of a 30-year experience with amniocentesis in a single tertiary medical center in Taiwan.

OBJECTIVE: Amniocentesis is a popular and effective prenatal diagnostic tool for chromosomal disorders. It is well-established that the risk of chromosomal abnormalities increases with maternal age; however, other related indications are seldom reported. Herein, we report our 30-year experience with amniocentesis from a single medical center, focusing on the indications and rates of abnormality. MATERIAL AND METHODS: A retrospective review of 16,749 pregnant women in the mid-trimester between January 1981 and December 2010 was conducted. The medical records were analyzed. RESULTS: The indications for amniocentesis were advanced maternal age (≥ 34 years old) (n=10,970, 65.5%), increasing-risk maternal triple-marker Down's screening test (≥ 1/270) (n=2090, 12.5%), history of abnormal offspring birth (n=792, 4.7%), abnormal ultrasound findings (n=484, 2.9%), parent with abnormal karyotype (n=252, 1.5%), family history of chromosomal abnormality (n=183, 1.1%), drug and radiation exposure (n=165), abnormal chorionic villus sampling (CVS) results (n=25), intrauterine fetal death (n=50), and other non-specific causes (n=1662, 9.9%). The rate of abnormality for each indication was 16% in the abnormal CVS group, 12% in the intrauterine fetal death group, 11.5% for parental chromosomal abnormality, 8.7% in the abnormal ultrasound finding group, 3.0% in the increasing-risk maternal triple-marker Down's screening test group, 2.5% in the advanced maternal age group, 1.5% for other non-specific causes, 1.4% for history of abnormal offspring birth, and 1.1% for family history of chromosomal abnormality. CONCLUSIONS: Both parents with abnormal karyotype and abnormal ultrasound findings are indications for which consideration of further amniocentesis is highly recommended.

Prenatal diagnosis of microdeletion 16p13.11 combination with partial monosomy of 2q37.1-qter and partial trisomy of 7p15.3-pter in a fetus with bilateral ventriculomegaly, agenesis of corpus callosum, and polydactyly.

OBJECTIVE: To present a prenatal diagnosis of microdeletion 16p13.11 with partial monosomy of 2q37.1-qter and partial trisomy of 7p15.3-pter in a fetus with bilateral ventriculomegaly, agenesis of corpus callosum, and polydactyly. CASE REPORT: A 41-year-old well-being Taiwanese, nulligravida woman received amniocentesis at a gestational age of 18 weeks for advanced maternal age. The fetus' karyotype showed 46,XY,der(2)t(2;7)(q36.2;p15.1). Both parents also received cytogenetic examinations and the mother's karyotype revealed 46,XX,t(2;7)(2q36.2;p15.1). High-resolution ultrasound showed the fetus had bilateral ventriculomegaly, agenesis of corpus callosum, and polydactyly of the right hand. After the termination of this pregnancy, the whole genome oligonucleotide-base array comparative genomic hybridization (CGH) by using fetal skin cells demonstrated a 8.44-Mb deletion at 2q37.1 (234602276-243041305), a 22.8-Mb duplication (65558-22869338) at 7p15.3, and an additional 1.32-Mb deletion (14968855-16292235) at 16p13.11. CONCLUSION: Array CGH is a useful tool not only to discover the genomic imbalance at the breakpoints as well as to detect unexpectedly complex rearrangements in other chromosomes. Our case also provided evidence that genomic aberration at chromosome 16p13.11 involves in the formation of polydactyly.