In the United States, many people with down syndrome and other intellectual and developmental disabilities were retained in inhumane institutions where they were denied education and health care. It is important to remember that during Hilter's leadership, people with down syndrome and other intellectual and developmental disabilities led to Hilter's first mass murders under Aktion-T4 program in 1939. Through it, it is said that over 200,000 people with disabilities were murdered and a large number being those with down syndrome. According to Global Down Syndrome Foundation, it stated that "In 1984, doctors in United States refused to offer lifesaving procedures to people with down syndrome e.g surgeries connected to the heart". Roughly 2500 years ago, Bernal and Briceno believed that some sculptures showed people with trisomy 21. They thought that potteries showed empirical indication for the existence of the disease. Martinez-Fraus recognised the syndrome in 500 patients with Alzheimer disease in which facial characteristics of trisomy 21 were distinctly displayed. Dissimilar scientists indicate evidence of the syndrome in 15th and 16th century paintings. Esquirol explained phenotypic description of trisomy 21 in 1838. People with down syndrome have been talked about in literature, science and art. Not until the late nineteenth century, that John Langdon Down, an English Physician, produced an accurate explanation of a person with down syndrome when his scholarly work was published in 1866. This earned him recognition of the "father" of syndrome. In recent history, advances in medicine and science have allowed researchers to look into the characteristics of people with Down Syndrome. In 1959, Jerome Lejeune the French Physician recognised down syndrome as a chromosomes condition. Rather of the usual 46 chromosomes present in each cell, Lejeune noticed 47 in the cells of the persons with down syndrome. Later it was considered that on extra partial or whole copy of chromosome 21 results in the characteristics associated with down syndrome. In the 2000s international team scientists successfully recognised and catalogued each of the approximately 329 genes in chromosome 21. This opened doors to greatly proceed with down syndrome research.
