Prenatal Diagnosis of Chromosomal Abnormalities through Amniocentesis

Benn, Peter

doi:10.1002/9781444314342.ch6

Cited by 14 publications

(17 citation statements)

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“…21 The overall frequency of deletions that we observed (1 out of 6800) is similar to the earlier estimate by Benn and Hsu in a metanalysis of studies of newborns. 2 In both, the most frequent deletion is of terminal 4p, with a frequency of 1 out of 21 000 and only 4q34-qter, 5p and 18q11 deletions showed frequencies higher than 1 out of 50 000 -each reported in two cases. All other deletions were found only once in the entire cohort.…”

Section: Discussionmentioning

confidence: 93%

Incidence of non-age-dependent chromosomal abnormalities: a population-based study on 88965 amniocenteses

2009

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Current knowledge about the incidence of chromosomal abnormalities in the general population comes from studies in newborns carried out in the 70s, before the era of widespread prenatal diagnosis. In the following years, data on frequency of chromosomal abnormalities in the second trimester of pregnancy have been used in conjunction with the data on the natural history of chromosomally abnormal fetuses to infer maternal age-specific rates of cytogenetic abnormalities in live-born infants. Starting from the data gathered in 1995 -1996 from all Italian cytogenetic laboratories (with 92% compliance to the study), we have compared the frequency of chromosomal abnormalities at amniocentesis in cases with maternal age of Z35 years (51 758 individuals) and cases with maternal age of o35 years (37 207 cases). The comparison confirmed the age-dependency of aneuploidies, whereas none of the structural abnormalities showed age-related differences. Furthermore, among the mosaic aneuploidies, trisomy 21 and 45,X/46,XX were found with a significantly higher incidence in older women. Chromosomal abnormalities that showed no significant difference between the two groups were summed for the overall national cohort, providing a general estimate of the incidence in the second trimester of pregnancy. The data provide critical background information for prenatal genetic counseling and for the planning of health care policy.

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Section: Discussionmentioning

confidence: 93%

Incidence of non-age-dependent chromosomal abnormalities: a population-based study on 88965 amniocenteses

2009

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“…Some laboratories have extended the testing to other autosomal trisomies . In the first trimester, this may identify pregnancies at high risk for spontaneous fetal loss, but in the second trimester, the clinical significance of a positive result is unclear . Some positive cases will be associated with confined placental mosaicism, but in rare instances, true fetal mosaicism could be present.…”

Section: General Considerations For Cfdna Screeningmentioning

confidence: 99%

“…In general, the phenotypes for each of these rare true mosaic conditions range from normal to a highly variable set of abnormalities that do not constitute well‐defined syndromes. Moreover, phenotypes cannot be accurately predicted from follow‐up cytogenetic analysis of amniotic fluid cells . A clinically significant uniparental disomy could also be present for chromosomes 6, 7, 11, 14, 15, and 20.…”

Section: General Considerations For Cfdna Screeningmentioning

confidence: 99%

Position statement from the Chromosome Abnormality Screening Committee on behalf of the Board of the International Society for Prenatal Diagnosis

et al. 2015

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“…Routine use of noninvasive prenatal diagnosis for Down syndrome as a complete replacement for current testing would therefore miss some of the other abnormalities currently identifiedthroughaprenatalsonographicexaminationandwould miss about 50% of all chromosome abnormalities now detectable through amniocentesis. 9 Balancing the benefits of noninvasive prenatal diagnosis against the more comprehensive detectioncurrentlyachievedbyinvasivetestingwouldberequired. After discussing with her physician or genetic counselor the risks and benefits of each approach, each patient would need to determine which type of testing she would prefer.…”

Section: Practical Issuesmentioning

confidence: 99%