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Monosomy 18p
1Cytogénétique AP-HP et Inserm U781, Université Paris Descartes, Hôpital Necker-Enfants Malades, 75015 Paris, France. turleau@necker.fr
Orphanet Journal of Rare Diseases
|February 21, 2008
Summary
Monosomy 18p is a chromosomal disorder affecting chromosome 18, characterized by mild features like short stature and intellectual deficiency. Genetic testing confirms diagnosis, with recurrence risks varying based on inheritance patterns.
Area of Science:
- Genetics
- Clinical Genetics
- Human Genetics
Background:
- Monosomy 18p is a chromosomal disorder caused by the deletion of part or all of the short arm of chromosome 18.
- It affects approximately 1 in 50,000 live births.
- Clinical manifestations are typically mild and non-specific, though a subset presents with severe malformations.
Purpose of the Study:
- To describe the clinical features, genetic causes, diagnostic methods, and recurrence risks associated with Monosomy 18p.
- To highlight the importance of cytogenetic analysis for accurate diagnosis and genetic counseling.
Main Methods:
- Review of clinical and cytogenetic data from patients with Monosomy 18p.
- Cytogenetic analysis (karyotyping, FISH, chromosomal microarray) for diagnosis.
- Prenatal diagnosis via amniocentesis or chorionic villus sampling.
Main Results:
- Common features include short stature, round face, palpebral ptosis, large ears, and mild to moderate intellectual deficiency.
- Genetic causes include terminal deletions, translocations, inversions, and ring chromosome 18.
- Recurrence risk is low for de novo events but significant with parental rearrangements.
Conclusions:
- Monosomy 18p diagnosis relies on cytogenetic analysis.
- Early intervention with speech therapy and educational programs can improve outcomes.
- Life expectancy is generally not significantly reduced, except in cases with severe brain malformations.
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