Chromosome 8 trisomy. Trisomy 8.
Incidence
In livebirths, trisomy 8 is almost always associated with mosaïcism and more than 100 cases have been reported so far. Complete trisomy 8 is a frequent cause of first trimester abortions. Live-born infants usually have trisomy 8 mosaicism (XXY or XX/XXY mosaicism)
Clinical Characteristics
Since mortality is high in utero, trisomy 8 is rarely observed at birth. In livebirths, trisomy 8 is almost always associated with mosaïcism and more than 100 cases have been reported so far. The incidence at birth is certainly low. Trisomy 8 mosaïcism is at the origin of moderate mental retardation, multiple skeletal anomalies, urogenital malformations, congenital heart defects, deep palmar and plantar furrows, distinct facial dysmorphism and agenesis of the corpus callosum. Trisomy of chromosome 8 is a syndrome with retarded psychomotor development, long and narrow trunk, dysmorphic facies with blank expression, musculoskeletal defects, eye anomalies, and visceral and other abnormalities.
Precipitants
none.
Provocation Tests
None.
Diagnostic Procedures
Karyotype is diagnostic. Live-born infants usually have trisomy 8 mosaicism (XXY or XX/XXY mosaicism) Some cases are associated with tetraploidy and trisomy 21.