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Psychology 2043B Week 3 Notes.docx

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Psychology 2043A/B
Esther Goldberg

Psychology 2043B – Exceptional Children: Developmental Disabilities Week 3: Risk Factors and Children at Risk Weekly Objectives 1. Develop an understanding of risk factors 2. Overview established risks, biological risks, and environmental risks 3. Provide some basic information about genetics and the types of genetic errors that can occur 4. Review the stages of foetal development and some of the major types of prenatal risk factors 5. Look at some of the different peri-natal and post-natal complications that can occur, including an overview of prematurity, low birth weight, and shaken baby syndrome 6. Provide an example of one type of environmental risk factor (lead poisoning) and its impact 7. Discuss the differences between primary, secondary, and tertiary prevention efforts Terminology  At risk refers to infants and young children who are physically, medically, or psychologically in danger of failing to thrive and also includes children who are affected by diverse economic, environmental, and geographical factors o Risk connotes a given probability but does not imply certainty, and not all children who fall within these categories of increased vulnerability become disabled  Risk factors are the biological or environmental causes of potential disabilities. When children are considered to be high risk or at risk, they are seen to be more prone to developing some form of disabling condition or for adverse effects of school learning and behaviour  Etiology: the process of finding causes to explain how a particular problem came into existence  Symptoms: the overt reactions or manifestations of the body to a certain condition  Symptomatology: the study of symptoms and characteristics  Teratology: the study of the agents involved in major congenital malformations  Pathophysiology: the adverse effects of a condition on development  Behavioural phenotype: patterns of behaviour or characteristics exhibited by individuals with a certain condition  We’re going to cover three types of risk: o Established Risks – genetic problems that invariably (always) lead to a developmental issue o Biological Risks – developmental events (e.g. prematurity; exposure to toxins) that place children at higher risk, but the outcome is not as certain o Environmental Risk – external factors beyond a child’s control that place children at higher risk for negative outcomes (e.g. environmental deprivation, impoverishment) A Bit About Genetics  Chromosomes are the things that make organisms what they are  Chromosomes are made up of DNA (or deoxyribonucleic acid) – the hereditary material in humans and almost all other organisms  Segments of DNA in specific patterns are called genes. Your genes make you who you are  In humans, each cell contains 23 pairs of chromosomes, for a total of 46  Twenty-rdo of these pairs, called autosomes, look the same in both males and females  The 23 pair, the sex chromosomes, differ between males and females. Females have two copies of the X chromosome, while males have one X and one Y chromosome  Each parent contributes one chromosome to each pair so that offspring get half of their chromosomes from their mother and half from their father Genetics – Things Can Go Wrong…  About 1 in 150 babies in the United States is born with a chromosomal abnormality  These abnormalities are caused by errors in the number or structure of chromosomes  Many children with a chromosomal abnormality have mental and/or physical birth defects  Some chromosomal abnormalities result in miscarriage or stillbirth  Egg and sperm cells each contain 23 chromosomes. When they join together, they form a fertilized egg with 46 chromosomes  Sometimes, something goes wrong before fertilization. An egg or sperm cell may divide incorrectly, resulting in an egg or sperm cell with too many or too few chromosomes. When this cell with the wrong number of chromosomes joins with a normal egg or sperm cell, the resulting embryo has a chromosomal abnormality  In most cases, an embryo with the wrong number of chromosomes does not survive  Other errors can occur before fertilization. These errors can alter the structure of one or more chromosomes. Individuals with structural chromosomal abnormalities usually have the normal number of chromosomes. However, small pieces of a chromosome (or chromosomes) may be deleted, duplicated, inverted, misplaced or exchanged with part of another chromosome  Monosomy: describes the absence of one member of a pair of chromosomes (i.e 45 chromosomes in each cell of the body instead of the usual 46)  Trisomy: describes the presence of an extra chromosome  Deletion: A small section of a chromosome is missing  Translocation: A section of a chromosome is attached to another chromosome  Inversion: A section of chromosome is snipped out and reinserted upside down  Duplication: A section of a chromosome is duplicated, so there is extra genetic material Established Risk  The established risk category refers to medical conditions and anomalies that invariably result in a disability or developmental delay. Established risk is most often related to genetic and chromosomal problems  Problems may range from relatively minor through to major difficulties, called the continuum of reproductive casualty  Genetic and Chromosomal Differences o All individuals are born with a unique combination of genes that are theirs alone from the moment of conception. One tiny flaw in the genetic structure can have tragic results  Chromosomal Disorders o Chromosomal problems result from chromosomal dysjunction, a malfunction in cell division. Problems occur when there is an extra chromosome, or when pieces or parts of chromosomes attach themselves to other chromosomes o The most common chromosomal aberration is Down syndrome. Fragile X syndrome is second only to Down syndrome among genetic abnormalities associated with intellectual disabilities  Genetic Disorders o There are a large number of confirmed or suspected dominant genetic disorders that can result in mental retardation and other disabilities. Congenital abnormalities, or hereditary abnormalities, are present at birth o Patterns of inheritance may be dominant, recessive, or multifactorial. Some disorders are linked to the genes on the twenty-third pair of chromosomes. In X- linked inheritance, the sons have a fifty-fifty chance of inheriting the condition through the mother  Inborn Errors of Metabolism o Metabolic problems due to hereditary are termed inborn errors of metabolism. Most inborn errors of metabolism are the result of the action of a single pair of genes. Many result in missing or defective enzymes. The absence of, or defect in, one of the enzymes means that the normal chemistry of a cell is altered by the inability to provide or dispose of a critical chemical or protein, which leads to unusual levels of particular chemicals in the body  Tay-Sachs Disease o Tay-Sachs results from an enzyme deficiency caused by a single autosomal recessive gene. Infants appear normal at birth, but the nervous system is gradually destroyed because of the missing enzyme, hexosamidose A. Death is inevitable, usually occurring between four and six years of age  Phenylketonuria (PKU) o PKU is a problem with modifier genes-genes that act on other genes and determine how the other genes express themselves. In PKU, the condition is marked by an inability to normally oxidize the amino acid phenylalanine, which is found in fish, dairy products, and most protein sources. Early screening and a special diet eliminates or diminishes the effects of PKU  Deletion Syndromes o In these rare diseases, it is not a case of aberrant genes. Rather, there is too little genetic material or there is at least one gene missing  Syndromes with Abnormal Chromosome Numbers o In a relatively high number of births (1 in 400), a disorder can be caused by an abnormal number of X or Y chromosomes. The most common variation is Klinefelter syndrome, which is found in 1 in every 700 male births Syndromes Caused By Trisomy  Trisomy 21 – Down Syndrome o Individuals with Down syndrome generally have three copies of chromosome 21 (instead of two) o Down syndrome is one of the most common chromosomal abnormalities, affecting about 1 in 800 babies. Males and females are about equally affected and the syndrome is reported in all races o The risk of Down syndrome and other trisomies increases with mother’s age o Features:  Individuals with Down syndrome have varying degrees of intellectual disability. Most have intellectual disabilities in the mild to moderate range  Other common characteristics include specific facial features and, often, heart defects and other problems  Persons with Down syndrome are living longer than ever before, but average life expectance is decreased  Males tend to be infertile; females have a high chance of passing on the disorder if they become pregnant  Trisomy 13 – Patau Syndrome o More severe than Down syndrome, but less common. Most affected babies die before their first birthday o Affects about 1 in 10,000-16,000 babies o Features:  Babies with trisomy 13 generally have severe mental retardation and many physical birth defects including extra fingers/toes, cleft lip and palate, small and close-set eyes, and small head (microcephaly)  Decreased muscle tone and seizures are also common  Trisomy 18 – Edwards Syndrome o Affects about 1 in 5,000 babies o Three times more common in females than males o Features:  Babies with trisomy 18 generally have severe mental retardation, small head (microcephaly), small jaw, and curved-bottom feet  Half of infants with this condition do not survive beyond the first week of life. Some children have survived to the teenage years, but with serious medical and developmental problems Abnormalities in the Sex Chromosomes  Turner Syndrome – Monosomy X o This abnormality affects about 1 in 2,500 girls o Girls with Turner Syndrome have one X chromosome and are missing all or part of the other X chromosome o Features:  They usually are infertile and do not undergo normal puberty changes unless they are treated with sex hormones  Affected girls are short, though treatment with growth hormone can help increase height  Common health problems include heart and kidney defects  Girls with Turner syndrome generally have normal intelligence, though some have learning difficulties, particularly with mathematics and special concepts  Klinefelter Syndrome – YXX o This abnormality affects about 1 in 500 to 1,000 boys o Boys with Klinefelter Syndrome have two, or occasionally more, X chromosomes along with their Y chromosome o Features:  Affected boys usually have normal intelligence, though many have learning problems  As adults, they produce lower-than-normal amounts of testosterone and are infertile  Triple X o About 1 in 1,000 females has an extra X chromosome o Features:  Affected girls tend to be tall  They usually have no physical birth defects, experience normal puberty and are fertile  Affected girls usually have normal intelligence, though many have learning problems  Because these girls are healthy and have a normal appearance, their parents often don’t know they have a chromosomal abnormality, although this abnormality can be detected if they have prenatal genetic testing done (e.g. with amniocentesis)  XYY o About 1 in 1,000 males is born with one or more extra Y chromosomes o Features:  Affected males are sometimes taller than average, have normal sexual development and are fertile  Most have normal intelligence, though some have learning, behavioural, and speech/language problems  As with triple X females, many affected males and their families don’t know they have a chromosomal abnormality unless it’s diagnosed with prenatal testing Biological Risk Factors  Children who are at biological risk have a history of developmental events, such as prematurity, that place them in the at-risk category.  Biological risks can occur at any point of child development: prenatally, perinatally, and postnatally  Prenatal Period – the months of pregnancy. The first three months of this time (the first trimester) is the most crucial period in development  Perinatal Period – from the end stage of pregnancy through the delivery and birth period and days immediately following the birth  Postnatal Period – the period after the birth  Critical Periods – a time during which a developing foetus or child is particularly sensitive or responsive to specific environmental influences Prenatal Risk Factors  Many agents act deleteriously on the developing foetus. Teratogens are environmental agents that can cause damage o Rubella: Rubella is a potential source of a variety of disabilities; when the mother contracts the virus in the first trimester of pregnancy, approximately 80 percent of fetuses are damaged. The foetal organs likely to be affected by rubella are those whose development is underway when the mother contracts the virus. The eye, ear, nervous system, and heart are especially vulnerable o Drugs: Drugs include over-the-counter drugs, prescription drugs, hard drugs, and alcohol and nicotine. In terms of children’s development, researchers are unable to conclusively identify a set of characteristics that represent prenatal drug exposure. Not only is it difficult to attribute specific characteristics to certain drugs, but caregiving of the infant serves to strengthen or mitigate unfortunate outcomes o Prescription Drugs: Prescription drgus have been shown to have an adverse effect on foetal development o Cocaine: Some neurochemical studies on cocaine in utero suggest that if it is present during gestation it may affect developing foetal neuromotor systems,
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