Trisomy 8 causes Warkany syndrome 2,^[1] a human chromosomal disorder caused by having three copies (trisomy) of chromosome 8. It can appear with or without mosaicism.

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Trisomy 8
Chromosome 8
Specialty	Medical genetics
Causes	three copies of chromosome 8

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Complete trisomy 8 causes severe abnormalities on the developing fetus and can be a cause of miscarriage.^[2][3] Complete trisomy 8 is usually a gestational lethal condition, whereas trisomy 8 mosaicism is less severe and individuals with a low proportion of affected cells may exhibit a comparatively mild range of physical abnormalities and developmental delay.^[4] Individuals with trisomy 8 mosaicism are more likely to survive into childhood and adulthood, and exhibit a characteristic and recognizable pattern of developmental abnormalities. Common findings include stunted psychomotor development, moderate to severe intellectual disability, variable growth patterns which can result in either abnormally short or tall stature, an expressionless face, and many musculoskeletal, visceral, and eye abnormalities, as well as other anomalies.^[5] A deep plantar furrow is considered to be pathognomonic of this condition, especially when seen in combination with other associated features.^[6] The type and severity of symptoms are dependent upon the prevalence of the affected cells and their location within the body.^{[citation needed]}

The simplest and easiest way to detect trisomy 8 is by a karyotype, a photograph representing all chromosomes of a cell in an orderly manner. Amniocentesis is also a technique for diagnosis. Samples from the amniotic fluid are taken from a fetus, cultured, then analyzed by a karyotype. If the photograph shows 3 copies of chromosome 8 instead of 2, then the individual has trisomy 8.

• Warkany syndrome 1