This article needs additional citations for verification. Developmental disability new methods of working with mentally retarded children a diverse group of chronic conditions that are due to mental or physical impairments.
Developmental disabilities cause individuals living with them many difficulties in certain areas of life, especially in “language, mobility, learning, self-help, and independent living”. Down syndrome is a condition in which people are born with an extra copy of chromosome 21. Normally, a person is born with two copies of chromosome 21. However, if they are born with Down syndrome, they have an extra copy of this chromosome. This extra copy affects the development of the body and brain, causing physical and mental challenges for the individual. CP is the most common motor disability in childhood. IQ below 70 along with limitations in adaptive functioning and onset before the age of 18 years.
The causes of developmental disabilities are varied and remain unknown in a large proportion of cases. Even in cases of known etiology the line between “cause” and “effect” is not always clear, leading to difficulty in categorizing causes. Genetic factors have long been implicated in the causation of developmental disabilities. There is also a large environmental component to these conditions, and the relative contributions of nature versus nurture have been debated for decades. Current theories on causation focus on genetic factors, and over 1,000 known genetic conditions include developmental disabilities as a symptom. The worldwide proportion of people with developmental disabilities is believed to be approximately 1.