Genetics presentation
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introduction, history, prevalence, characteristics, symptoms, facts, diagnosis, treatment, life expectancy, future.
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Genetics presentation
- 1. Prader Willi Syndrome Hiba Nasir 1248129 Genetics Presentation
- 3. Brief introduction • Rare • Developmental disability • 15th chromosome • hypothalamus doesn't work properly • Key feature: hunger games. • Not INHERITED disease – Only 1%
- 4. Genetics • Lack of 7 active genes on chromosome 15 • (15q11-q13) • Genes normally active on paternal chromosome.
- 5. • 70% • Paternal 15, PWS region deleted/missing Paternal deletion • 25%-28% • Both copies from mother Maternal uniparental disomy • 2% • Genes are present but do not work. • Inherited Imprinting defect
- 7. History • 1956 • Andrea Prader, Heinrich Willi, Alexis Labhart. • Also called: Prader Labhart Willi syndrome.
- 8. Prevalence • 1 in 10,000 to 30,000 people worldwide. • Not racial- both sexes
- 9. Characteristics • Dysfunction of hypothalamus • Responsible for functions like: – Hunger, temperature and pain regulation, puberty, emotions, and fertility. • Unclear how genetic abnormality leads to hypothalamic dysfunction.
- 10. Symptoms First stage (hypotonia) Hypotonic , low muscle tone. Weak cry and a poor suck reflex are typical. Low levels of GH Physical abnormalities: narrow forehead, almond-shaped eyes, triangular mouth, short stature, small hands and feet Second stage (hyperphagia) An unregulated appetite. Most common 2-6 years. Individuals with PWS lack normal hunger and satiety cues. M.R of persons with PWS is lower than normal. Leads to morbid obesity Low sex hormone levels (hypogonadism)
- 12. More symptoms o Behavioral problems, such as stubbornness or temper tantrums o Delayed motor skills and speech, not sporty. o Cognitive problems, ranging from near normal intelligence to mild mental retardation; learning disabilities are common o Repetitive thoughts and verbalizations o Collecting and hoarding of possession.
- 13. Facts • It is a SPECTRUM DISORDER • Mental strengths • Normal lifespan • Diabetes and Obsessive Compulsive Disorder • Depression is common
- 14. Diagnosis • FISH (fluorescence in situ hybridization) Specific DNA sequences on chromosomes. High degree of sequence similarity. Fluorescence microscopy can be used to find out where the fluorescent probe bound to the chromosomes. FISH is often used for finding specific features in DNA for use in genetic counseling, medicine, and species identification. FISH can also be used to detect and localize specific mRNAs within tissue samples. In this context, it can help define the spatial-temporal patterns of gene expression within cells and tissues.
- 15. DNA Methylation
- 16. Treatment • Human growth hormone therapy • Physical therapy • Behavioral therapy • Medications • Sex hormone treatments • Diet control • Speech therapy
- 17. Life expectancy • High • Sufferers are expected to live a normal healthy life
- 18. Hope for the future • More research • Focus on obesity • Hope today- for a cure tomorrow
Editor's Notes
- PWS is caused by a lack of active genetic material in a particular region of chromosome 15 (15q11-q13). Or fail to inherit genes in the critical region Normally, individuals inherit one copy of chromosome 15 from their mother and one from their father. The genes in the PWS region are normally only active on the chromosome that came from the father. In PWS, the genetic defect causing the inactivity of chromosome 15 from the father (paternal chromosome 15) can occur in one of three ways:
- Approximately 70% cases. Most common. Part of chromosome 15 inherited from child’s father – PWS critical gene area – is missing/deleted Baby inherits both copies of chromosomes 15 from on parent – the mother. Maternal = mother Uniparental = 1 parent Disomy = 2 chromosomes Due to dna methylation or translocation or mutation. 1% chance of inheriting the defective chromosome 15 from father.
- Prader-Willi syndrome affects an estimated 1 in 10,000 to 30,000 people worldwide.
- Symptoms are believed to be caused by dysfunction of a portion of the brain called the hypothalamus. The hypothalamus is a small endocrine organ at the base of the brain that plays a crucial role in many bodily functions like, hunger and satiety, temperature and pain regulation, fluid balance, puberty, emotions, and fertility. Although hypothalamic dysfunction is believed to lead to the symptoms of PWS, it is unclear how the genetic abnormality causes hypothalamic dysfunction.
- Stage 1 In the first stage, infants with PWS are hypotonic or "floppy", with very low muscle tone. Weak cry and a poor suck reflex are typical. Babies with PWS usually are unable to breastfeed and frequently require tube feeding. These infants may suffer from "failure to thrive" if feeding difficulties are not carefully monitored and treated. As these children grow older, strength and muscle tone generally improve. Motor milestones are achieved, but are usually delayed. Stage 2: An unregulated appetite characterizes the second stage of PWS. This stage most commonly begins between ages 2 and 6 years old. Individuals with PWS lack normal hunger and satiety cues. They usually are not able to control their food intake and will overeat if not closely monitored. Food seeking behaviors are very common. In addition, the metabolic rate of persons with PWS is lower than normal. Left untreated, the combination of these problems will lead to morbid obesity and its many complications.
- Behavioral problems, usually during transitions and unanticipated changes, such as stubbornness or temper tantrums Delayed motor skills and speech due to low muscle tone Cognitive problems, ranging from near normal intelligence to mild mental retardation; learning disabilities are common Repetitive thoughts and verbalizations Collecting and hoarding of possessions Picking at skin Low sex hormone levels sex organs never develop fully and males and females are both sterile
- Prader-Willi syndrome is considered a spectrum disorder, meaning not all symptoms will occur in everyone affected and the symptoms may range from mild to severe. People with Prader-Willi often have some mental strengths as well, such as skills in jigsaw puzzles. If obesity is prevented, people with the syndrome can live a normal lifespan. PRADER WILLI often times results in diabetes and Obsessive Compulsive Disorder
- his test may also be called Southern Hybridization Methylation Specific PCR Assay or Methylation Specific PCR Test. The key word is "Methylation" and it is the most sensitive diagnostic test for Angelman Syndrome. This test will positively identify about 80% of individuals with Angelman Syndrome. Methylation refers to a chemical "tag" added to DNA and can be used to identify whether the DNA was contributed by the mother or the father. Where this tag is added occurs in a distinct pattern if it came from the mother and a different distinct pattern if it came from the father. The pattern of this tag can be examined to determine which parent contributed the DNA. The DNA methylation test will determine if an individual has one of each pattern (one from each parent) or an Angelman Syndrome pattern (where only the pattern from the father is present.) Using our encyclopedia analogy, DNA is like the pages inside the encyclopedia volumes. The methylation test is like opening the two "volumes" of chromosome 15 and looking up the page of the specific "chapter" contributed by each parent to see which parent's pattern is visible on the page. In the methylation test, these individuals will show only the methylation pattern from the mother and are missing the pattern from the father.
- No cure. But there are ways to improve the qualitry of life of prader willi suffereres In multiple studies, human growth hormone (HGH) has been found to be beneficial in treating Prader-Willi syndrome. In June of 2000, HGH was officially recognized by the Federal Drug Administration (FDA) in the United States and other countries for use in patients with Prader-Willi syndrome. HGH is effective not only in increasing height, but also Decreasing body fat, increasing muscle mass Improving weight distribution Increasing stamina, Increasing bone mineral density Physical therapy. Muscle weakness is a serious problem among individuals with PWS. For children younger than age 3, physical therapy may increase muscular strength and help such children achieve developmental milestones. For older children, daily exercise will help build lean body mass. Behavioral therapy. People with PWS have difficulty controlling their emotions. Using behavioral therapy can help. Stubbornness, anger, and obsessive-compulsive behavior, including obsession with food, should be handled with behavioral management programs using firm limit-setting strategies. Structure and routines also are advised.1,5 Medications.Medications, especially serotonin reuptake inhibitors (SRIs), may reduce obsessive-compulsive symptoms. SRIs also may help manage psychosis. Sex hormone treatments and/or corrective surgery.These treatments are used to treat small genitals (penis, scrotum, clitoris). Restricted access to food and strict supervision of food intake may be required.