Genetically determined disordersGGenetically determined disordersGenetically determined disordersEnglishNeonatologyNewborn (0-28 days)BodyNAConditions and diseasesAdult (19+)NA2009-10-18T04:00:00ZAndrew James, MBChB, MBI, FRACP, FRCPC12.000000000000030.00000000000001808.00000000000Flat ContentHealth A-Z<p>Read about genetic disorders that can affect a newborn baby. Genetic disorders such as phenylketonuria, sickle cell, and cystic fibrosis are discussed.</p><p>Many congenital abnormalities and diseases are inherited. If both the mother and father carry the trait for a genetically determined abnormality or disease, the baby has at least a one in four chance of inheriting that condition. </p><h2>Key points</h2> <ul><li>Genetically determined disorders include metabolic disorders, blood disorders, cystic fibrosis, congenital hypothyroidism, congenital hyperplasia and congenital hearing loss.</li> <li>Genetic tests can be done before and during pregnancy to determine if the mother and father carry traits for these diseases.</li></ul>
Maladies génétiquesMMaladies génétiquesGenetically determined disordersFrenchNeonatologyNewborn (0-28 days)BodyNAConditions and diseasesAdult (19+)NA2009-10-18T04:00:00ZAndrew James, MBChB, MBI, FRACP, FRCPC12.000000000000030.00000000000001808.00000000000Flat ContentHealth A-Z<p>Apprenez-en davantage sur les troubles génétiques qui peuvent toucher les nouveau-nés. On y discute des maladies génétiques comme la phénylcétonurie, l’anémie drépanocytaire et la fibrose kystique.</p><p>De nombreuses anomalies et maladies congénitales sont héréditaires. Si la mère et le père sont porteurs du caractère d'une anomalie ou d’une maladie génétique, le bébé a au moins une chance sur quatre d'hériter de ce problème.</p><h2>À retenir</h2> <ul><li>Les maladies génétiques comprennent des troubles métaboliques, des troubles sanguins, la fibrose kystique, l’hypothyroïdie congénitale, l’hyperplasie surrénale congénitale et la déficience auditive congénitale.</li> <li>Des examens génétiques peuvent être faits avant et pendant la grossesse afin de déterminer si la mère ou le père sont porteurs des traits de ces maladies.</li></ul>

 

 

Genetically determined disorders472.000000000000Genetically determined disordersGenetically determined disordersGEnglishNeonatologyNewborn (0-28 days)BodyNAConditions and diseasesAdult (19+)NA2009-10-18T04:00:00ZAndrew James, MBChB, MBI, FRACP, FRCPC12.000000000000030.00000000000001808.00000000000Flat ContentHealth A-Z<p>Read about genetic disorders that can affect a newborn baby. Genetic disorders such as phenylketonuria, sickle cell, and cystic fibrosis are discussed.</p><p>Many congenital abnormalities and diseases are inherited. If both the mother and father carry the trait for a genetically determined abnormality or disease, the baby has at least a one in four chance of inheriting that condition. </p><h2>Key points</h2> <ul><li>Genetically determined disorders include metabolic disorders, blood disorders, cystic fibrosis, congenital hypothyroidism, congenital hyperplasia and congenital hearing loss.</li> <li>Genetic tests can be done before and during pregnancy to determine if the mother and father carry traits for these diseases.</li></ul><p>Genetically determined disorders include metabolic disorders such as phenylketonuria; blood disorders such as sickle cell anemia and thalassemia; and other conditions such as cystic fibrosis, congenital hypothyroidism, congenital adrenal hyperplasia, and congenital hearing loss. </p><p>Before and during pregnancy, genetic tests can be done to determine whether the mother and father carry the traits for these diseases. If both parents carry the trait, the baby is at increased risk of developing the disease. At birth, newborn screening tests are important to the diagnosis of many of these disorders. </p><h2>Metabolic disorders</h2><p>Genetically determined metabolic disorders are rare conditions that affect about one in 2000 newborn babies. These conditions can cause serious illness, and may cause death. These disorders are caused by the failure of enzymes involved in metabolic processes to function normally. There may be a partial or absolute deficiency of the enzyme, or a deficiency of a cofactor that is necessary for the enzyme to function properly. </p><p>Clinical recognition of these disorders leads to specific blood and urine tests that are used to make the diagnosis of the metabolic disorder. Sometimes the diagnosis can only be confirmed by specialized tests of skin, muscle, or liver. </p><h3>Phenylketonuria</h3><p>One of the best-known genetically determined metabolic disorders is phenylketonuria. It is a rare genetically determined disorder where the body is unable to use an important amino acid called phenylalanine. As a result, phenylalanine builds up in the body. This compound is toxic to the central nervous system and can cause brain damage. </p><p>Babies with phenylketonuria may develop early symptoms such as vomiting, irritability, and rash. There may be increased muscle tone and more active reflexes of the muscle tendons. If left untreated, the condition causes severe intellectual disability, tremors, seizures, decreased body growth, and a smaller than normal head size. Other symptoms may include movement disorders, rocking, and hyperactivity. </p><p>Phenylketonuria is an easily diagnosed disease that can be detected by using a simple blood test shortly after birth. Newborn babies should be screened for their phenylalanine levels about three days after they are born. </p><p>Treatment consists of eating a special diet that is extremely low in phenylalanine. Phenylalanine is found in high amounts in milk, eggs, and other common foods, and therefore, these foods should be minimized and supplemented with other foods. Babies with phenylketonuria can be given a special formula that is low in phenylalanine. The low-phenylalanine diet is very important, especially when the child is growing. The child should be closely supervised by their parents, a registered dietitian, and their physician, to make sure they are following the diet closely. This is a lifelong treatment and most adults who follow their treatment plan have normal or near-normal intellectual function. </p><h3>Other genetically determined metabolic conditions</h3><p>Twenty other inherited metabolic conditions have been recommended for inclusion in newborn screening tests. If diagnosed early, many of these conditions can be effectively managed. Newborn screening programmes vary from region to region. You may obtain further information about your region’s screening programme from your baby’s health-care providers. </p><h2>Blood disorders: Sickle cell anemia and thalassemia</h2><p>Sickle cell anemia and thalassemia are genetically determined blood disorders that are also recommended for inclusion in newborn screening programs. </p><h3>Sickle cell anemia</h3><p>Sickle cell anemia is a disease caused by a type of hemoglobin that has an abnormal structure. Hemoglobin is a protein carried by the red blood cells, which bring oxygen to all the parts of the body. </p> <figure class="swf-asset-c-80"><span class="asset-image-title">Sickle Cell Blood Flow</span> <div class="asset-animation"> src="https://akhpub.aboutkidshealth.ca/Style%20Library/akh/swfanimations/swf.html?swffile=Sickle_cell_MED_ANI_EN.swf" </div> <figcaption class="asset-image-caption">Healthy red blood cells are soft, round and flexible. Sickled red blood cells are sticky and hard and can block blood flow.</figcaption> </figure> <p>In sickle cell anemia, the blood cells become sickle-shaped. The odd shaped, abnormal blood cells can become stuck in the smaller blood vessels and cause a blockage. When a blood vessel is blocked, it stops oxygen from getting to the places where it is needed, such as important organs. When the organs do not receive enough oxygen, they can become damaged and this causes severe pain.</p><p>Babies and children with sickle cell anemia are at risk for serious bloodstream or chest infections caused by the pneumococcus bacterium, especially in their first five years of life. These infections can be fatal. However, if diagnosed early, babies and children can be given regular preventive antibiotic treatment and be adequately vaccinated. Their parents can also be properly educated to recognize early signs of infection. </p><p>Sickle cell anemia is associated with many other complications. The recurrent episodes of blood vessel blockage can result in severe pain to the bones and joints. Often hospitalization is required for adequate pain control. Stroke in early childhood is not uncommon. Hip disease is one severe complication resulting in the need for hip replacement over time. Complications related to the spleen can lead to the development of serious and sometimes fatal bloodstream infections and pneumonia. However, early intervention can make a difference. </p><p>If a newborn baby is screened and diagnosed with sickle cell anemia at birth, preventive antibiotic treatment called pneumococcal prophylaxis can be started within the first two to three months of life. Pneumococcal prophylaxis is very helpful in preventing infection and saving lives. A baby who is diagnosed with sickle cell should also be vaccinated with the pneumococcal and meningococcal immunizations, to further prevent infection. </p> <figure><span class="asset-image-title">Sickle Cell </span><span class="asset-image-title">Heredity</span><img src="https://assets.aboutkidshealth.ca/akhassets/Sickle_cell_heredity_MED_ILL_EN.jpg" alt="" /><figcaption class="asset-image-caption">In</figcaption><figcaption class="asset-image-caption"> this example, both parents are carriers of the sickle cell trait, but they do not have the disease themselves. If a baby inherits only one copy of the gene, they will not have the disease (but will be a carrier). If a baby inherits two copies of the gene they will have sickle cell disease.</figcaption> </figure> <h3>Thalassemia</h3><p>The thalassemias are a group of genetically determined blood diseases that produce an abnormal hemoglobin in the red blood cells. Children with thalassemia develop anemia. </p><p>There are two types of thalassemia, alpha thalassemia and beta thalassemia, depending on which protein chain of the hemoglobin molecule is missing in the red blood cells. Thalassemia is also categorized into three groups, depending on its severity: thalassemia major is the most severe form, thalassemia intermedia is a less severe form, and thalassemia minor may cause no symptoms at all. </p><p>Children with thalassemia are usually well at birth but soon develop symptoms of paleness, headaches, fatigue, shortness of breath, jaundice, and enlargement of the spleen. They may not want to eat and they may vomit frequently after feedings. If left untreated, the disease will cause death by age one to eight years. </p><p>Thalassemia major is treated with a combination of antibiotics and sometimes blood transfusions. The transfusions, which occur about once a month, are aimed at keeping the hemoglobin level near normal to prevent the complications of anemia. Frequent transfusions also help to enhance the child’s growth and health, and prevent heart failure and bone deformities. Thalassemia major can be cured with a bone marrow transplant. </p> <figure><span class="asset-image-title">Beta Thalassemia </span><span class="asset-image-title">Heredity</span><img src="https://assets.aboutkidshealth.ca/akhassets/Beta_thal_MED_ILL_EN.jpg" alt="" /><figcaption class="asset-image-caption">In</figcaption><figcaption class="asset-image-caption"> this example, both parents are carriers of beta thalassemia. They may have mild anemia. Their children may inherit one, two, or no copies of the beta thalassemia gene. If a baby inherits one copy of the gene, they will have thalassemia trait like their parents. If a baby inherits two copies, they will have beta thalassemia (moderate to severe anemia).</figcaption> </figure> <h2>Other inherited disorders</h2><p>A number of other genetically determined disorders, such as congenital hypothyroidism, congenital adrenal hyperplasia, cystic fibrosis, and hearing loss, have been recommended for inclusion in newborn screening programs.</p><h3>Congenital hypothyroidism</h3><p>Congenital hypothyroidism is inadequate thyroid hormone production in newborn babies. This can occur because of a structural defect in the thyroid gland, an enzyme failure that causes a problem with thyroid metabolism, or iodine deficiency. </p><p>By definition, congenital hypothyroidism is present at, or before, birth. Babies with congenital hypothyroidism who do not receive appropriate treatment can develop profound intellectual disability because brain development is dependent upon thyroid hormone during the first two to three years of life. They may also have other features due to the deficiency of thyroid hormone. </p><p>Early diagnosis is the key to providing the baby with appropriate medical care. As a result, congenital hypothyroidism is screened at birth in most countries. Early and appropriate treatment of this condition can prevent severe intellectual disability and other neurological complications. Thyroid hormone replacement is necessary to bring the baby’s thyroid levels to normal. Iodine is also important, and is most commonly provided in table salt. </p><h3>Congenital adrenal hyperplasia</h3><p>Congenital adrenal hyperplasia (CAH) refers to a group of genetically determined disorders relating to the adrenal glands. CAH creates an overproduction of a "male" hormone called androgen. Generally, if untreated, these children will grow very fast at first but the growth stops early and they will be small as adults. </p><p>In boys, this virulization, as it is called, may also mean an enlarged penis and the development of male secondary sexual characteristics such as facial hair and Adam’s apple as early as age three. </p><p>For the girls, these secondary sex characteristics associated with males will also develop, but medications can control these aspects of development and put these children into the normal range. In girls where there has been a marked amount of virulization, the clitoris can be quite large, resembling a penis and, when erect, can be noticeable through clothing – all very awkward for a young girl. In these cases, most parents choose surgery to correct the problem. </p><p>In addition to these effects, CAH can interfere with the body’s ability to retain salt, a condition which is serious and potentially life-threatening. </p><p>For the most part, these effects of CAH, including the dangerous salt-wasting, can be treated with hormone replacement therapy which counteracts the overproduction of androgens. Some jurisdictions routinely test for the disorder at birth and the condition can be detected, and in some cases treated, in utero. </p><h3>Cystic fibrosis</h3><p>Cystic fibrosis is a life-threatening genetically determined disease where abnormally thick, sticky mucus clogs the lungs and can result in fatal lung infections. The mucus can also block the pancreas and make it difficult for the child to absorb nutrients in food. The mucus can block the bile ducts of the liver and cause permanent damage. </p><p>The symptoms of cystic fibrosis vary from child to child. The most common symptoms are persistent cough, frequent pneumonia, wheezing, shortness of breath, failure to gain weight normally, and difficulty having bowel movements. As the child becomes an adult, additional complications may arise such as cystic fibrosis-related diabetes or osteoporosis. </p><p>Prompt diagnosis and aggressive treatment can extend the lives of children with cystic fibrosis. Treatment depends on the stage of the disease and the organs involved. Mucus must be cleared from the lungs on a daily basis using physical therapy or a variety of medications. If the pancreas is affected, a high calorie diet and vitamins are required. Pancreatic enzyme replacements are usually needed to help the person absorb nutrients properly. </p><h3>Congenital hearing loss</h3><p>Congenital hearing loss or congenital deafness is a partial or complete loss of hearing in one or both ears, due to abnormal development of the ears in pregnancy. Most cases of congenital deafness have genetic causes. Therefore, if you or your partner has a family history of congenital hearing loss, there is a chance that your baby could also develop this condition. Congenital deafness can also be caused by certain infections during pregnancy, such as rubella, cytomegalovirus, and toxoplasmosis. </p>https://assets.aboutkidshealth.ca/AKHAssets/genetically_determined_disorders_newborn.jpgGenetically determined disorders

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