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2023 ACMG Annual Clinical Genetics Meeting Digital ...
Maternal implications of Triple X syndrome detecte ...
Maternal implications of Triple X syndrome detected after abnormal NIPT and inconclusive expanded carrier screening. A case-report.
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Triple X syndrome, also known as Trisomy X or 47XXX, is a rare genetic condition in which females have an extra X chromosome. This condition is often the result of an error in maternal nondisjunction during meiosis, where the X chromosomes fail to separate during cell division. In a normal XX female, one X chromosome is deactivated by DNA methylation, but may still have genetically active pseudoautosomal regions. In Trisomy X, two of the three X chromosomes are deactivated, leading to potential overexpression of genes that have escaped X-inactivation.<br /><br />Phenotypic variability in Triple X syndrome includes dysmorphic features, learning difficulties, neuropsychiatric manifestations, seizures, genitourinary anomalies, and premature ovarian failure. It is the most common female chromosomal abnormality, occurring in about 1 in 1000 female births. Non-invasive prenatal testing (NIPT) and expanded carrier screening are commonly offered to pregnant patients in the first trimester to screen for chromosomal disorders in the fetus.<br /><br />In a case report presented, atypical sex chromosome findings on NIPT and inconclusive expanded carrier screening led to the diagnosis of Trisomy X syndrome in the mother. The importance of understanding the implications of maternal sex chromosome abnormalities in prenatal testing is highlighted. Individuals with a sex chromosome abnormality should be counseled about the possibility of inconclusive NIPT or carrier screening results for X-linked disorders and sex chromosome abnormalities. This is crucial for appropriate management of future pregnancies and decisions regarding invasive diagnostic testing.<br /><br />The case report emphasizes the need for clarification tests, such as maternal karyotyping and microarray analysis, when abnormal prenatal genetic testing results are obtained. The interpretation of these results requires collaboration between obstetric clinicians and genetic specialists. Understanding the genetic basis and maternal implications of Triple X syndrome can guide appropriate counseling and management of affected individuals.
Asset Subtitle
Co-Author - Emily D. Slutsky, MD, MS; Co-Author - Oxana Zarudskaya, MD; Presenting Author - Stephanie Hopp, DO, MHS, MS; Co-Author - Katherine Chen, MD, MD;
Meta Tag
Cell free DNA/cfDNA
Chromosomal Abnormalities
Counseling
Prenatal Diagnosis
X-Inactivation/X-Linked Disease
Co-Author
Emily D. Slutsky, MD, MS
Co-Author
Oxana Zarudskaya, MD
Co-Author
Katherine Chen, MD, MD
Presenting Author
Stephanie Hopp, DO, MHS, MS
Keywords
Triple X syndrome
Trisomy X
47XXX
genetic condition
extra X chromosome
nondisjunction
meiosis
X-inactivation
dysmorphic features
learning difficulties
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