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2023 ACMG Annual Clinical Genetics Meeting Digital ...
Diagnosis of Thrombocytopenia Absent Radius (TAR) ...
Diagnosis of Thrombocytopenia Absent Radius (TAR) Syndrome After Abnormal First Trimester Ultrasound: A Case Report
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Pdf Summary
This case report discusses a rare autosomal recessive disorder called Thrombocytopenia Absent Radius (TAR) syndrome. This syndrome is characterized by thrombocytopenia (low platelet count) and the absence of the radii in both arms. Other skeletal abnormalities and additional features such as congenital heart defects and kidney defects can also be present. Differential diagnosis for radial ray defects includes other syndromes like Fanconi anemia, Holt-Oram syndrome, and Roberts syndrome. TAR syndrome is caused by changes in the RNA-binding motif protein 8A gene.<br /><br />In this case, a first trimester ultrasound showed abnormal findings, including cystic hygroma and abnormal limb development, which led to the suspicion of TAR syndrome. A chromosomal microarray analysis confirmed a deletion in the RBM8A gene at 1q21.1, indicating a genetic diagnosis of TAR syndrome in the fetus. The patient opted for termination of the pregnancy due to the severity of the ultrasound findings.<br /><br />Parental testing revealed that the patient was negative for the 1q21.1 deletion and a specific variant in the RBM8A gene, while the partner tested positive for the variant. A re-evaluation of the prenatal microarray analysis showed a smaller deletion below the reporting threshold.<br /><br />This case highlights the importance of early diagnosis of skeletal dysplasia through the first trimester anatomy scan. It also emphasizes the need for increased scrutiny of the 1q21.1 region in cases of suspected radial ray defects.
Asset Subtitle
Presenting Author - Nicole Poulos, MS; Co-Author - Millie A. Ferres, MD; Co-Author - Zena Wolf, PhD; Co-Author - Christine R. Bryke, MD; Co-Author - Karen Marchand, MS; Co-Author - Paula Delerme, MS; Co-Author - Julie Howell, MS; Co-Author - Barbara O'Brien, MD;
Meta Tag
Bone/Joint Abnormalities
Congenital Anomaly
Genetic Testing
Prenatal Diagnosis
Ultrasound
Variant Detection
Co-Author
Millie A. Ferres, MD
Co-Author
Zena Wolf, PhD
Co-Author
Christine R. Bryke, MD
Co-Author
Karen Marchand, MS
Co-Author
Paula Delerme, MS
Co-Author
Julie Howell, MS
Co-Author
Barbara O'Brien, MD
Presenting Author
Nicole Poulos, MS
Keywords
Thrombocytopenia Absent Radius syndrome
autosomal recessive disorder
low platelet count
absence of radii
skeletal abnormalities
congenital heart defects
chromosomal microarray analysis
RBMA8A gene deletion
genetic diagnosis
skeletal dysplasia
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