الفهرس 
Down syndromeOnly 14 pages are availabe for public view
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Abstract
Down syndrome (DS) or trisomy 21 is the most frequent genetic cause of mental retardation.
| الفهرس | Only 14 pages are availabe for public view
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Abstract Down syndrome (DS) or trisomy 21 is the most frequent genetic cause of mental retardation. | |||||||||||||||