Other common features include: a flat and wide face, a short neck, excessive joint flexibility, extra space between big toe and second toe, abnormal patterns on the fingertips and short fingers. Instability of the atlantoaxial joint occurs in about 20% and may lead to spinal cord injury in 1–2%. Hip dislocations may occur without trauma in up to a third of people with Down syndrome.Growth in height is slower, resulting in adults who tend to have short stature—the average height for men is 154 cm (5 ft 1 in) and for women is 142 cm (4 ft 8 in). Individuals with Down syndrome are at increased risk for obesity as they age. Growth charts have been developed specifically for children with Down syndrome. Neurological
This syndrome causes about a third of cases of intellectual disability. Many developmental milestones are delayed with the ability to crawl typically occurring around 8 months rather than 5 months and the ability to walk independently typically occurring around 21 months rather than 14 months.Most individuals with Down syndrome have mild (IQ: 50–69) or moderate (IQ: 35–50) intellectual disability with some cases having severe (IQ: 20–35) difficulties. Those with mosaic Down syndrome typically have IQ scores 10–30 points higher than that. As they age, people with Down syndrome typically perform worse than their same-age peers.Commonly, individuals with Down syndrome have better language understanding than ability to speak. Between 10 and 45% have either a stutter or rapid and irregular speech, making it difficult to understand them.
The discovery took place in the laboratory of Raymond Turpin at the Hôpital Trousseau in Paris, France. Jérôme Lejeune and Marthe Gautier were both his students.As a result of this discovery, the condition became known as trisomy 21. Even before the discovery of its cause, the presence of the syndrome in all races, its association with older maternal age, and its rarity of recurrence had been noticed. Medical texts had assumed it was caused by a combination of inheritable factors that had not been identified. Other theories had focused on injuries sustained during birth. Society and culture
Name
Due to his perception that children with Down syndrome shared facial similarities with those of Blumenbachs Mongolian race, John Langdon Down used the term "mongoloid". He felt that the existence of Down syndrome confirmed that all peoples were genetically related. In the 1950s with discovery of the underlying cause as being related to chromosomes, concerns about the race-based nature of the name increased.In 1961, a group of nineteen scientists suggested that "mongolism" had "misleading connotations" and had become "an embarrassing term". The World Health Organization (WHO) dropped the term in 1965 after a request by the delegation from the Mongolian Peoples Republic. While the term mongoloid (also mongolism, Mongolian imbecility or idiocy) continued to be used until the early 1980s, it is now considered unacceptable and is no longer in common use.In 1975, the United States National Institutes of Health (NIH) convened a conference to standardize the naming and recommended replacing the possessive form, "Downs syndrome" with "Down syndrome".