Developmental Psychology

3.2 Genetic and Chromosomal Abnormalities It is proven that a person having too many chromosomes or fewer chromosomes can lead to many types of syndromes . Before we start looking at the genetic and chromosomal abnormalities, let’s define syndromes. They are a cluster of symptoms that usually occur together. There are numerous genetic diseases. Below is a few that are more predominate or well known. • Down Syndrome : Down Syndrome is also known as Trisomy 21 . A childwho is born with Down Syndrome has 1 extra copy of chromosome 21. So instead of having the 2 that most individuals have, they are born with 3 chromosome 21s. There can be a lot of accompanying diseases and medical problems that come with having this syndrome. Although there are some problems that may accompany Down Syndrome, most individuals who have it will live well into their adulthood. Individuals with Down Syndrome has distinct facial features. They have round faces, thick tongues and sometimes slanted eyes. There are also some who develop mental retardation as well. Although the degree of mental retardation varies, a lot of individuals who have Down Syndrome can live on their own and do quite well. • Phenylketonuria: This abnormality is also referred to as PKU and refers to the abnormal digestion of amino acids and phenylalanine. Phenylalanine, which is a necessary amino acid is found in many foods that we eat. This abnormality is a recessive gene. This means that the child’s parents are possible carriers, who are unaware of the gene. One of the ways to reduce the symptoms of this abnormality is to be on a specific diet, with restrictions. • Huntington’s Disease: Huntington’s is a dangerous and potentially fatal neuromuscular degenerative disease. This disease, which is a dominate one, usually develops in someone’s mid-thirties. • Kleinfelter’s Syndrome: This is a sex-linked chromosomal abnormality. This syndrome is caused by an individual having an extra X chromosome (XXY). It is males who are typically affected by this and usually are rendered infertile and cause a mild degree of mental retardation. It has been said that this syndrome is difficult to diagnose and is often misdiagnosed. • Fragile X Syndrome : This syndrome is where the X chromosome has the ability to break and the pieces may fall apart. This is not a sex-linked abnormality, and the severity of the syndrome depends on how much of the X chromosome is missing. Some of the symptoms of Fragile X include, having a larger head than normal, larger ears than normal, as well as mental retardation. • Turner’s Syndrome : Turner’s is more frequently found in women and occurs when a woman only has one X chromosome. Those who have Turner’s will typically have learning disabilities such as ADD/ADHD. Getting pregnant is also a problem with Turner’s. When there are secondary characteristics that develop, and it is rare, some will develop a webbed neck. • Other Sex-Linked Abnormalities : There are many sex-linked abnormalities that happen to be linked with having an extra sex chromosome. There is an increased risk of medical and mental problems that will occur. This occurs when there is an additional sex chromosome that is added.

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