When is the year when down syndrome was discovered?

Answer 1

In 1959 the cause of Down syndrome was discovered to be due to the trisomy 21. Down syndrome or trisomy 21 was first described by the british doctor John Langdon Down in 1866 and also happens to be named after him.

Answer 2

Down syndrome or trisomy 21 (or Down's syndrome in British English and WHO ICD) is a chromosomal disorder caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British Doctor Who described the syndrome in 1866. The disorder was identified as a chromosome 21 trisomy by Jérôme Lejeune in 1959. The condition is characterized by a combination of major and minor differences in structure. Often Down syndrome is associated with some impairment of cognitive ability and physical growth as well as facial appearance. Down syndrome can be identified during pregnancy or at birth. Individuals with Down syndrome tend to have a lower than average cognitive ability, often ranging from mild to moderate mental disabilities. A small number have severe to profound mental disability. The incidence of Down syndrome is estimated at 1 per 800 to 1,000 births, although these statistics are heavily influenced by the age of the mother. Other factors may also play a role. Many of the common physical features of Down syndrome also appear in people with a standard set of chromosomes. They may include a single transverse palmar crease (a single instead of a double crease across one or both palms, also called the Simian crease), an almond shape to the eyes caused by an epicanthic fold of the eyelid, upslanting palpebral fissures, shorter limbs, poor muscle tone, a larger than normal space between the big and second toes, and protruding tongue. Health concerns for individuals with Down syndrome include a higher risk for congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. Early childhood intervention, screening for common problems, medical treatment where indicated, a conducive family environment, and vocational training can improve the overall development of children with Down syndrome. Although some of the physical genetic limitations of Down syndrome cannot be overcome, education and proper care will improve quality of life.

Example of white spots on the iris known as Brushfield spots

Individuals with Down syndrome may have some or all of the following physical characteristics: oblique eye fissures with epicanthic skin folds on the inner corner of the eyes, muscle hypotonia (poor muscle tone), a flat nasal bridge, a single palmar fold, a protruding tongue (due to small oral cavity, and an enlarged tongue near the tonsils), a short neck, white spots on the iris known as Brushfield spots, excessive joint laxity including atlanto-axial instability, congenital heart defects, excessive space between large toe and second toe, a single flexion furrow of the fifth finger, and a higher number of ulnar loop dermatoglyphs. Most individuals with Down syndrome have mental retardation in the mild (IQ 50-70) to moderate (IQ 35-50) range, with individuals having Mosaic Down syndrome (explained below) typically 10-30 points higher. In addition, individuals with Down syndrome can have serious abnormalities affecting any body system. They also may have a broad head and a very round face.

Down syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on the 21st chromosome, either in whole (trisomy 21) or part (such as due to translocations). The effects of the extra copy vary greatly among people, depending on the extent of the extra copy, genetic history, and pure chance. Down syndrome occurs in all human populations, and analogous effects have been found in other species such as chimpanzees and mice. Recently, researchers have created transgenic mice with most of human chromosome 21 (in addition to the normal mouse chromosomes). The extra chromosomal material can come about in several distinct ways. A typical human karyotype is designated as 46,XX or 46,XY, indicating 46 chromosomes with an XX arrangement typical of females and 46 chromosomes with an XY arrangement typical of males.

Answer 3

In 1866 John Langdon, an English doctor published a description of the condition. It wasn't until 1959 that Professor Jerome Lejeune proved that Down's syndrome is a chromosomal irregularity.

Answer 4

it happens when chromosomes don't separate correctly during meiosis