Genetic Disorders

Genetic Disorders

This presentation will focus on genetic disorders. Try to recall the information you learned in the presentation about conception during this presentation. 1What is a Genetic Disorder?Caused by abnormalities in an individuals genetic material (the DNA, or the genome). There are four different types of genetic disorders:Single-gene is mutatedMultifactorial problemsChromosomal changes-entire areas of the chromosome can be missing or misplaced.Teratogenic problems

When we were learning about conception, we learned that a babys DNA is created through the combining of the parents genes. We also learned that dominant genes will mask a recessive gene. Well, a genetic disorder is caused by abnormalities in an individuals genetic material also known as DNA or the genome. There are four types of genetic disorders. They are single gene mutations, multifactorial problems, chromosomal changes, and teratogenic problems. We will look more into each type in the following slides. 2Single Gene MutationA single gene is responsible for abnormalityGreater risks of inheritanceDominant: One of the genes from the parent is abnormalRecessive: Both parents have abnormal genes.X-linked: Determined by the genes on the X chromosome. (Mainly affects males)

In single gene mutation, a single gene is responsible for a defect or abnormality. Single gene disorders usually have greater risks of inheritance.There are three types of single gene disorders. They are dominant, recessive, and x-linked. Dominant is when an abnormality occurs when only one of the genes from one parent is abnormal. If the parent has the disorder, the baby has a 50 percent chance of inheriting it. Examples of this type are achondroplasia and Marfan syndrome. The second type on single gene mutation is recessive. Recessive is when an abnormality only occurs when both parents have abnormal genes. If both parents are carriers, a baby has a 25 percent chance of having the disorder.Examples of this type include cystic fibrosis, sickle cell disease, and Tay-Sachs disease. The final type of single gene mutation is x-linked. This is when the disorder is determined by genes on the X chromosome. Males are mainly affected and have the disorder. Daughters of men with the disorder are carriers of the trait and have a one in two chance of passing it to their children. Sons of women who are carriers each have a one in two chance of having the disorder. Examples of this are Duchenne muscular dystrophy and hemophilia. 3Multifactorial ProblemsMultiple genes mutatedEnvironmental effectsOther unknown factorsExamples:Heart defectsCleft lip or cleft palateNeural tube defects

Some birth defects do not follow a single gene or chromosomal abnormality pattern. They may be due to several problems, or a combined effect of genes and the environment. It is difficult to predict inheritance of abnormalities caused by multiple factors. Examples include heart defects, cleft lip or cleft palate, and neural tube defects (defects in the spine or brain). The image on this slide shows an example of cleft lip and cleft palate. 4Chromosomal AbnormalitiesMay be inherited or occur with no family historyAneuploidy: More or few chromosomes than normalDeletion: Part of a chromosome is missingInversion: Chromosome breaks and reattaches itself upside downTranslocation: Rearrangement of a chromosome segment from one location to the other Mosaicism: Presence of two or more chromosome patterns in the cells of a person

Chromosomal abnormalities are when there is a problem with the chromosomes. These may be inherited from the parents or they may occur with no family history at all. Listed are the five most common chromosomal problems. Aneuploidy is when there are more or fewer chromosomes than the normal number. A very common form of this is Down Syndrome because cells contain an extra chromosome 21. Deletion occurs when part of a chromosome is missing or when part of the DNA code is missing. Inversion is when a chromosome breaks and the piece of the chromosome turns upside down and reattaches itself. Inversions may or may not cause birth defects depending on their exact structure. Translocation is a rearrangement of a chromosome segment from one location to another, either within the same chromosome or to another. There are two types of translocation and they are balanced translocation and Robertsonian translocation. Mosaicism occurs if there is the presence of two or more chromosome patterns in the cells of a person, resulting in two or more cell lines (for example, some with 46 chromosomes, others with 47).5Teratogenic Problems Occur when the baby is exposed to certain substancesDuring the first trimester- organs are formingKnown teratogens:Certain medicationsAlcoholRadiationLeadCertain infections

Our presentation about avoiding dangers to the baby focuses on teratogenic problems that lead to birth defects through genetic mutations. Teratogenic problems occur when the fetus is exposed to teratogens, which are substances that cause abnormalities, during the first trimester of pregnancy when the organs of the baby are forming. Some teratogens that you should be aware of are certain medications, alcohol, exposure to high levels of radiation, lead, and certain infections such as rubella. 6Top Ten Most Common Genetic DisordersCystic FibrosisHuntingtons Disease Down SyndromeDuchenne Muscular DystrophySickle Cell Anemia

Celiac DiseaseBecker Muscular DystrophyNoonan SyndromeThalassemiasTurner Syndrome

We will now look at ten of the most common genetic disorders. They include: Cystic FibrosisHuntingtons Disease Down SyndromeDuchenne Muscular DystrophySickle Cell AnemiaCeliac DiseaseBecker Muscular DystrophyNoonan SyndromeThalassemiasTurner Syndrome

7Cystic FibrosisAffects the cells that produce mucus, sweat, and digestive juices.Secretions are thick and block tubes, ducts, and passageways.Symptoms:Difficulty breathingRecurrent lung infectionsDigestive issuesReproductive issues

Cystic fibrosis affects the cells that produce mucus, sweat and digestive juices. These secreted fluids are normally thin and slippery. But in cystic fibrosis, a defective gene causes the secretions to become thick and sticky. Instead of acting as a lubricant, the secretions plug up tubes, ducts and passageways, especially in the lungs and pancreas. There are many symptoms that are a result of this genetic disorder, but the slide lists only a few. The majority of the symptoms are a result of the lung and digestive pathways being blocked which then leads to problems with the lungs and digestive system. Specific symptoms include difficulty breathing, recurrent lung infections, and poor weight gain and growth.

The picture on this slide helps you understand how it is passed down from parents to the children. 8Huntington's DiseaseCauses the progressive breakdown of nerve cells in the brain Can cause:Problems with movement Thinking disordersPsychiatric disordersUsually develop signs and symptoms around age 30 or 40

Huntingtons disease causes the progressive breakdown of nerve cells in the brain. It has a broad impact on a persons functional abilities and can cause a variety of problems. They are problems with movement like involuntary jerking or muscle problems, thinking or cognitive disorders like difficulty in learning new information and lack of impulse control, and psychiatric disorders like social withdrawal or bipolar disorder. Most people with Huntington's disease develop signs and symptoms in their 30s or 40s, but the onset of the disease may be earlier or later in life. 9Down SyndromeAbnormal cell division results in extra genetic material from chromosome 21Leads to:Lifelong intellectual disabilitiesDevelopmental delaysSome health problemsThere are some common features that are a result of Down syndrome

Down syndrome is a genetic disorder caused when abnormal cell division results in extra genetic material from chromosome 21. This genetic disorder, which varies in severity, causes lifelong intellectual disability and developmental delays, and in some people it causes health problems. Each person with Down syndrome is an individual intellectual and developmental problems range from mild to moderate, and some people are healthy while others have severe health problems such as serious heart defects. Children with Down syndrome have a distinct facial appearance. Though not all children with Down syndrome have the same features, some of the more common features are flattened facial features, small head, short neck, protruding tongue, upward slanting eyes, unusually shaped ears, poor muscle tone, and short height.

10Duchenne Muscular DystrophyCauses progressive weakness and loss of muscle massSymptoms usually begin in childhood (age 2-3)Typically affects boysSymptoms:Frequent fallsTrouble running and jumpingMuscle painLarge calf musclesWalking on the toes

Duchenne muscular dystrophy is one of the many forms of muscular dystrophy that causes progressive weakness and loss of muscle mass. Because this is an x-linked genetic mutation, it typically affects boys. The symptoms usually begin to show around age 2 or 3 and include frequent falls, trouble running and jumping, muscle pain, large calf muscles, and walking on the toes. Take a look at the calf muscles of the little boy in the photo on this slide. 11Sickle Cell AnemiaLack of healthy red blood cells to carry oxygenBlood cells become rigid and stickyNo cure but treatments can relieve painSymptoms:Episodes of painFrequent infectionsVision problemsDelayed growth

Sickle cell anemia is an inherited form of anemia a condition in which there aren't enough healthy red blood cells to carry adequate oxygen throughout your body. Normally, your red blood cells are flexible and round, moving easily through your blood vessels. In sickle cell anemia, the red blood cells become rigid and sticky and are shaped like sickles or crescent moons. These irregularly shaped cells can get stuck in small blood vessels, which can slow or block blood flow and oxygen to parts of the body. There's no cure for most people with sickle cell anemia. However, treatments can relieve pain and help prevent further problems. Some symptoms of sickle cell anemia are episodes of pain, frequent infections, vision problems, and delayed growth. 12Celiac DiseaseImmune reaction to eating glutenInflammation of the small intestine when gluten is consumedCan deprive other important organs of nutrientsSymptoms:Digestive problemsHeadaches and fatigueDiarrhea Weight loss Swollen belly

Celiac disease is an immune reaction to eating gluten, a protein found in wheat, barley and rye. The picture on this slide shows items that contain gluten. If you have celiac disease, eating gluten triggers an immune response in your small intestine. Over time, this reaction produces inflammation that damages the small intestine's lining and prevents absorption of some nutrients (malabsorption). The intestinal damage can cause weight loss, bloating and sometimes diarrhea. Eventually, your brain, nervous system, bones, liver and other organs can be deprived of vital nourishment. Symptoms of this disease include digestive problems, headaches and fatigue, diarrhea, weight loss, and a swollen belly in children. There's no cure for celiac disease but following a strict gluten-free diet can help manage symptoms and promote intestinal healing.13Becker Muscular DystrophyDegenerative disease that affects voluntary musclesOnset is late childhood or adolescence Gets worse at a much slower rate than DMDSymptoms:Difficulty walking (usually unable at age 30)Loss of muscle massFrequent fallsMuscle weakness

Becker muscular dystrophy (BMD)is one of nine types of muscular dystrophy, a group of genetic, degenerative diseases primarily affecting voluntary muscles. Becker MD onset is usually in late childhood or adolescence, and the course is slower and less predictable than that of Duchennes MD. Becker muscular dystrophy is very similar toduchenne muscular dystrophy, except that it gets worse at a much slower rate and it is less common. Symptoms include loss of muscle mass, frequent falls, muscle weakness, and difficulty walking. Usually by age 30, the person is no longer able to walk. 14Noonan SyndromePrevents normal developmentMay cause:Unusual facial characteristicsShort statureHeart defectsOther physical problemsAbout 80% people affected have congenital heart disease

Noonan syndrome is a genetic disorder that prevents normal development in various parts of the body. A person can be affected by Noonan syndrome in various ways. These include unusual facial characteristics, short stature, heart defects, other physical problems and possible developmental delays. About 80% of people who have Noonan syndrome are faced with congenital heart disease. The photo on this slide features a child who has the unusual facial characteristics that are a result of Noonan syndrome. 15ThalassemiaBlood disorderLess hemoglobinFewer red blood cellsCan cause anemiaSymptoms:FatigueWeaknessPale appearanceFacial bone deformities

Thalassemia (thal-uh-SEE-me-uh) is an inherited blood disorder characterized by less hemoglobin and fewer red blood cells in your body than normal.Hemoglobin is the substance in your red blood cells that allows them to carry oxygen. The low hemoglobin and fewer red blood cells of thalassemia may cause anemia, leaving you fatigued. Some common symptoms of thalassemia are fatigue, weakness, pale appearance or yellow discoloration to the skin, and facial bone deformities. 16Turner SyndromeOnly affects femalesOccurs when the X chromosome is missing or partially missingCan be found before birthSymptoms:Delayed growthHeart defectsLearning disabilitiesShort statureWeb like neck

Turner syndrome, a condition that affects only girls and women, results when a sex chromosome (the X chromosome) is missing or partially missing. The image of this slide depicts this. Turner syndrome can cause a variety of medical and developmental problems, including short height, failure to start puberty, infertility, heart defects, certain learning disabilities and social adjustment problems. Turner syndrome may be diagnosed before birth (prenatal), during infancy or in early childhood. Occasionally the diagnosis is delayed until the teen or young adult years in those who have mild signs and symptoms of Turner syndrome. 17Referenceshttp://www.activebeat.com/your-health/children/the-10-most-common-genetics-disorders/http://www.doctorslounge.com/studlounge/downdirty/genetic.htmhttp://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=90&ContentID=P02505