Down syndrome

SYD: 37

Down syndrome

Description: Trisomy 21 (Down syndrome) is caused by triplicate state (trisomy) of all or a critical portion of chromosome 21. It is the most frequent form of mental retardation caused by a microscopically demonstrable chromosomal aberration, and characterized by well-defined and distinctive phenotypic features, characteristic facies, specific major congenital malformations such as those of the heart (30-40% in some studies), particularly the atrioventricular canal, and of the gastrointestinal tract, such as duodenal stenosis or atresia, imperforate anus, and Hirschsprung disease and natural history. Mapping of the chromosomal region that, if triplicated, results in the phenotypic characteristics of Down syndrome has been facilitated by the use of DNA samples from individuals who have partial trisomy 21 with or without features of the Down syndrome phenotype. Although detailed analysis of these DNAs is still under way, an area of approximately 5 Mb between loci D21S58 and D21S42 has been identified that is associated with mental retardation and most of the facial features of the syndrome.

There are no synonyms for this combination.

Category: Syndrome

Developmental anomalies

Listed in the combination's profile :

There are no developmental anomalies for this combination.

Observed in MDB cases:

There are no developmental anomalies for this combination.
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Associated malformative diseases
Associated genes
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