What are the impacts on pregnancy for a deletion of chromosome 17?

From the Guidelines

Chromosome 17 deletions during pregnancy can have significant impacts on fetal development, increasing the risk of miscarriage, intrauterine growth restriction, and congenital anomalies, with the severity varying widely based on the specific genes affected. The impacts of chromosome 17 deletions on pregnancy can be substantial, potentially leading to developmental abnormalities in the fetus, such as Miller-Dieker syndrome or Smith-Magenis syndrome, depending on the size and location of the deletion 1.

Key Considerations

• The risk of major structural anomalies is elevated, even in fetuses found to be euploid, highlighting the importance of early fetal anatomic surveys and second-trimester anatomic surveys 1.
• The sensitivity of ultrasound at 11 to 14 weeks for detecting congenital anomalies is about 50%, compared to 75% at 18 to 22 weeks, emphasizing the need for serial fetal surveillance 1.
• Pregnancies with increased nuchal translucency, such as those potentially associated with chromosome 17 deletions, should be offered genetic counseling and invasive diagnostic testing, with cell-free fetal DNA screening also supported by ACOG for initial screening 1.

Management and Prognosis

• Management involves a multidisciplinary approach, including maternal-fetal medicine specialists, geneticists, and neonatologists, to monitor fetal development and prepare for potential complications at birth 1.
• The long-term prognosis depends on the specific deletion, with some causing intellectual disability, developmental delays, and physical abnormalities requiring lifelong support, while smaller deletions may have milder effects 1.
• Early intervention services should be arranged before birth when possible to optimize outcomes for affected children, considering the potential for significant impacts on quality of life and morbidity 1.

From the Research

Impacts of Chromosome 17 Deletion on Pregnancy

• Chromosome 17 deletion can result in various structural or functional abnormalities, including kidney and urethra issues, type 5 diabetes (MODY5), and neurodevelopmental or neuropsychiatric disorders 2.
• Microdeletion of chromosome 17q12 has been associated with specific clinical presentations, and prenatal diagnosis can be achieved through techniques such as amniocentesis and copy number variation sequencing (CNV-seq) 2.
• Noninvasive prenatal testing (NIPT) can also be used to screen for fetal chromosome 17 microduplication, with a positive predictive value of 75.0% 3.
• The detection of chromosome 17 deletion or microduplication during pregnancy can have significant implications for prenatal diagnosis and counseling, highlighting the importance of comprehensive genetic testing and analysis 2, 3.

Prenatal Diagnosis and Testing

• Invasive prenatal diagnosis techniques, such as amniocentesis and chorionic villus sampling, can be used to detect chromosomal abnormalities, including chromosome 17 deletion 4, 5.
• Noninvasive prenatal testing (NIPT) is a screening tool that can be used to detect fetal aneuploidies and chromosomal microduplications, including those affecting chromosome 17 3.
• The combination of karyotype analysis, CNV-seq, and whole-exome sequencing (WES) can provide a detailed understanding of the fetal genome and help identify potential genetic abnormalities 2.

Clinical Implications and Findings

• The detection of chromosome 17 deletion or microduplication during pregnancy can have significant clinical implications, including an increased risk of structural or functional abnormalities and neurodevelopmental disorders 2.
• Prenatal diagnosis and counseling can help families prepare for the potential risks and complications associated with chromosome 17 deletion or microduplication 2, 3.
• Further research is needed to fully understand the clinical implications and findings associated with chromosome 17 deletion or microduplication, as well as the effectiveness of different prenatal diagnosis techniques 3.