However, it would be a mistake to assume that the clinical features of Down syndrome are only due to a handful of genes being overexpressed. You can think of the overexpressed gene products interacting with a number of normal gene products, each product individualized by the person's unique genetic makeup, and thus being thrown "out of genetic balance." This would then make the person more susceptible to other genetic and environmental insults, leading to the features, diseases and conditions associated with Down syndrome. It is this complex arrangement that scientists will be addressing in the second century of Down syndrome research.
Down Syndrome Clinical Program. Learn more about the Down Syndrome Program at Mass General, including prenatal services and clinics for infants and ...
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Higher rates of tooth wear and bruxism are also common.  Other common oral manifestations of Down syndrome include enlarged hypotonic tongue, crusted and hypotonic lips, mouth breathing, narrow palate with crowded teeth, class III malocclusion with an underdeveloped maxilla and posterior crossbite , delayed exfoliation of baby teeth and delayed eruption of adult teeth, shorter roots on teeth, and often missing and malformed (usually smaller) teeth.     Less common manifestations include cleft lip and palate , enamel hypocalcification (20% prevalence). 
The chance of having a baby with Down syndrome increases as a woman gets older. Down syndrome cannot be cured. Early treatment programs can help improve skills. They may include speech, physical, occupational, and/or educational therapy. With support and treatment, many people with Down syndrome live happy, productive lives.