This paper provides a comprehensive overview of Down syndrome (trisomy 21), a chromosomal condition caused by the presence of an extra copy of chromosome 21. It examines the genetic mechanisms behind the syndrome, its physical and cognitive characteristics, and the range of developmental variation among affected individuals. Drawing on research from education, medicine, and developmental psychology, the paper addresses language and learning profiles, hypotonia, Alzheimer's disease risk in adults, sexual development and contraception, and adult health care management. The paper emphasizes that significant individual variation exists and that early intervention, accurate diagnosis, and realistic expectations are essential to supporting people with Down syndrome throughout their lives.
The paper demonstrates effective synthesis of source material. Rather than summarizing each source in isolation, the writer weaves together findings from Dykens, Appl, Chicoine, and others to build a coherent, cumulative argument. Direct quotations are used selectively and purposefully — supporting claims without replacing the writer's analytical voice.
The paper moves logically from foundational science (genetics, history) through developmental considerations (language, motor skills, medical conditions), and on to complex adult issues (Alzheimer's risk, sexuality, health care). Each section draws on at least one primary source and introduces new dimensions of the topic, making the paper progressively more nuanced without losing coherence. The conclusion is embedded in the final section rather than stated separately, ending on a positive note about increasing life expectancy.
Down syndrome, detected in approximately one in 1,000 people every year, occurs when a person inherits three copies of chromosome 21 rather than the normal complement of two. This presence of an extra set of genes leads to over-expression and increased production of certain protein products that cause the abnormalities observed in the syndrome (Murphy pp).
Every child with Down syndrome will possess some level of learning disorder, ranging from severe to very mild intellectual disability; however, the majority will learn to walk, talk, read, and write (Murphy pp). Roughly 40% of infants born with Down syndrome will have some sort of heart defect, such as a hole in the heart (Murphy pp). There can also be problems regulating temperature, which can cause very dry skin. Additionally, a weakened immune system is common in these infants, making them prone to infections, especially chest and sinus infections (Murphy pp). Children with Down syndrome generally have chubby faces with protruding eyes and tongues, eyes that slant outward and upward, ears that are smaller than normal, and a flat back of the head (Murphy pp).
In 1866, John Langdon Down published an essay describing a group of children with common features who were distinct from other children with intellectual disabilities (Murphy pp). He referred to these children as "Mongoloids" because of his belief that they looked similar to people from Mongolia, who at the time were mistakenly thought to have an arrested development (Murphy pp). Down believed the condition to be a result of tuberculosis in the parents. The term "Mongoloid" continued to be used until the 1960s, when the condition became known as Down syndrome (Murphy pp).
During the 1930s, researchers first began to speculate that Down syndrome was caused by chromosomal abnormalities. In 1959, researchers Jerome Lejeune and Patricia Jacobs discovered the cause to be triplication of chromosome 21 (Murphy pp). Down syndrome, also called trisomy 21, occurs when there is an extra copy of chromosome 21 — the smallest of the 23 human chromosomes — and this extra set of genes results in over-expression of the involved genes, causing increased production of certain protein products (Murphy pp). For most genes, over-expression has little effect; however, the genes that contribute to Down syndrome are exceptions. It is believed that only a small number of genes spread across the chromosome are involved in causing the syndrome (Murphy pp).
There is a wide variety of features and characteristics among people with trisomy 21. One factor is that genes are triplicated, but genes also come in different forms called alleles, and the effect of over-expression can depend on which allele is present (Murphy pp). Penetrance also plays a part, meaning that the same allele that causes a condition in one person may have no effect on another (Murphy pp). Furthermore, in a small percentage of cases, other chromosomal variations are responsible for Down syndrome rather than classic trisomy 21 (Murphy pp).
In the June 22, 2002 issue of the Journal of Special Education, Elizabeth M. Dykens states that Down syndrome is the most common genetic, chromosomal cause of intellectual disability, and that in nearly all cases it is caused by a third copy of chromosome 21 (Dykens pp). Aside from particular genetic and physical features, the majority of children with Down syndrome display specific problems in linguistic grammar, expressive language, and articulation (Dykens pp). For example, "most children with Down syndrome do not progress grammatically beyond the 3-year level, and their grammatical abilities almost invariably fall below their overall mental age levels" (Dykens pp). Moreover, skills in expressive language, as opposed to those in receptive language, are more significantly delayed (Dykens pp). By the time children's mental ages reach twenty-four months, remarkable delays of six or more months in expressive language abilities are evident in 83% to 100% of children with Down syndrome (Dykens pp). Regarding articulation, 95% of parents of children with Down syndrome report that others show at least occasional difficulties understanding their child's speech (Dykens pp).
Dykens also reports that other areas are relatively strong in most children with Down syndrome (Dykens pp). Researchers have found that, on average, school-age children with Down syndrome demonstrate levels of visuo-spatial short-term memory that are one or more years advanced over identical auditory or verbal short-term memory tasks (Dykens pp). As Dykens notes, such "relative strengths arise even when subtests from different psychometric instruments are used to measure verbal short-term memory and when researchers use either scaled or age-equivalent scores in their analyses" (Dykens pp). Thus, as a group, children with Down syndrome show significant deficits — beyond mental-age expectations — in grammar, expressive language, and articulation, yet also demonstrate relative strengths in visual short-term memory tasks (Dykens pp).
Although no cure or prevention has yet been found, research indicates that the limitations associated with Down syndrome are not as uniformly extensive as once thought (Appl pp). In the September 22, 1998 issue of Childhood Education, Dolores Appl states that while the exact upper developmental limits or the changes over the lifespan are not fully understood, it is known that intervention can help children with Down syndrome reach their potential (Appl pp). Down syndrome is a fairly common and well-known condition; however, misconceptions often lead to stereotyping, which can be distressing to parents and detrimental to children due to the potential for low expectations in the learning environment (Appl pp).
Children born with Down syndrome are more likely than typically developing children to possess particular characteristics, yet not all children will be affected similarly, nor will the degree of involvement be the same (Appl pp). Moreover, certain characteristics — such as those related to language development — may become more pronounced with age (Appl pp). Appl notes that characteristics found in individuals with Down syndrome may also be found in individuals with other syndromes, and it is not yet known whether any characteristics are unique to Down syndrome (Appl pp). It is therefore important that educators not uniformly apply characteristics to all children with Down syndrome; rather, "the characteristics should be used as a means for understanding and supporting individual children with Down syndrome within the specific contexts of their physical and social environments" (Appl pp). Appl cautions that considerable variation exists in the physical development, medical conditions, mental abilities, and behavior of individuals with Down syndrome (Appl pp).
You’re 43% through this paper. Sign up to read the remaining 4 sections.
Sign Up Now — Instant Access Already a member? Log inAlways verify citation format against your institution’s current style guide requirements.