Category Archives: Genetic Diseases Affecting Kids
Long QT Syndrome (Prlonged QT Syndrome)
Long QT Syndrome (Prlonged QT Syndrome) is caused by a defect in the heart’s electrical circuit, often resulting in loss of consciousness. It may also cause sudden death due to heart failure.
- Genetic defects, heart disorders and using certain drugs can result in long QT syndrome.
- Abnormally fast heart rate, which reduces the efficiency of the heart, is the cause of the common symptom of sudden loss of consciousness.
- An ECG and stress test can confirm long QT syndrome.
- The condition is usually treated with beta-blockers. Implanting pace makers may help regularize the heart beat. A surgical procedure may be beneficial in some cases.
The interval between two consecutive points on the electrocardiogram is referred to a QT. In those who have long QT syndrome, this interval is abnormally prolonged. This condition usually affects one in 7,000 people. It has a fatal outcome in more than 3,000 children and youngsters in the United States alone. A genetic defect is the usual cause for long QT syndrome in children. Screening for genetic abnormalities may help diagnose this condition. This abnormality may be common within the family if some other members have suffered sudden deaths without any apparent reason. Use of certain drugs or some other disorder may precipitate long QT syndrome too. This is the usual cause for this condition developing in the adults.
In people with long QT syndrome, abnormally fast heart rate may develop at the time physical exertion, or with emotional excitement. When the heart beats too fast, its capacity to pump out sufficient amount of blood becomes greatly reduced. Inadequate blood supply to the brain often results in sudden unconsciousness. It can even be fatal. Deafness is common in people with this abnormal condition.
An ECG may be conducted on children, as well as adults, who have become suddenly unconscious without any apparent reason. Often, some form of stress is introduced during the test so that the performance of the heart can be better assessed. A person at rest can take the test after the administration of certain drugs into the vein. In exercise tress testing, the person either walks on the treadmill or works on an exercise bicycle during the test. It can simulate the working of the heart during exertion.
Drug treatment with beta-blockers is often effective in most people who have the long QT syndrome. In some cases, drug therapy may not yield the desired results. Such people may benefit from the installation of pacemakers to regulate the abnormal heart rate. Some people may need a combination of a defibrillator and a pacemaker. The implanted defibrillator can deliver an electric shock to the heart whenever a lethal heart rhythm develops. It can revive the heart and prevent fatal heart attacks. Some children with long QT syndrome may have to be restricted from competitive sports due to the high risk of sudden death occurring during exertion.
A surgical alternative found to be effective in preventing abnormally fast heart rate is termed cervicothoracic sympathectomy. In this procedure, a nerve located in the neck is severed, as it has the effect of preventing abnormally high heart rate, which is the cause of loss of consciousness and sudden death due to heart failure.
Watch this Video: What is Long QT Syndrome?
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XYY Syndrome (Jacobs syndrome)
The XYY Syndrome (Jacobs syndrome) results from a genetic abnormality which occurs due to the presence of an extra copy of Y chromosome in the male child.
The usual symptoms associated with XYY syndrome include language difficulties and lower intelligence quotient. Learning disabilities, attention deficit disorder, behavioral problems, and hyperactivity, are also common. The affected boys usually grow tall.
Earlier, criminal behavior and aggressiveness were considered to be typical of men with XYY syndrome, but such link has been found to be absent.
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Klinefelter’s Syndrome
Klinefelter’s syndrome results from a genetic abnormality characterized by the presence of an extra X chromosome in male children, in addition to the normal XY configuration.
- Klinefelter’s syndrome is caused by an extra X chromosome.
- Lower IQ, learning difficulties, especially with respect to language, and infertility, are the usual symptoms. Small testes, and long hands and legs, are typical physical features associated with Klinefelter’s syndrome.
- The abnormality is usually diagnosed at puberty when typical symptoms start appearing.
- Hormone treatment with the male hormone testosterone may help people with Klinefelter’s syndrome.
Klinefelter’s syndrome is a commonly occurring genetic abnormality. However, external physical abnormalities and symptoms are not many; hence this condition is not usually suspected in the newborn. Affected boys may grow tall and their hands and legs also may be very long too. Slightly reduced intelligence quotient is common. They may have problems with speech and communication. Their verbal intelligence may be comparatively low, with considerable difficulty in expressing themselves. Inability for planning, learning from mistakes, lack of judgment and insight, are some of the deficiencies which may get the affected boys into trouble frequently while growing up.
The boys affected by Klinefelter’s syndrome usually reach puberty normally, even though their testes may remain smaller than normal. Gynecomastia, or enlargement of breasts, may occur at the time of puberty, while facial hair may be scanty. In spite of certain pubertal changes occurring at the normal age, the affected youngsters remain infertile. They have a higher risk of developing several disorders such as hypothyroidism, diabetes mellitus, varicose veins, and chronic lung disease, when compared to normal men. The incidence of breast cancer is also higher in men with this abnormality.
Among those who have Klinefelter’s syndrome, some may have more than 2 copies of X chromosomes in addition to the normal Y chromosome. Up to 5X chromosomes have been detected in some cases. The more the number of extra X chromosomes, the worse the symptoms associated with this abnormality. About 15-point reduction in IQ is found to be associated with each of the extra copy of X. Language skills, especially with respect to communication, and self expression, are greatly affected.
Klinefelter’s syndrome is not usually suspected until the affected boys reach puberty, as most of the typical symptoms start developing around that time. A chromosome analysis may help confirm the diagnosis. In many cases, the syndrome is not detected till men undergo infertility assessment as part of infertility treatment. Almost all men with this condition are infertile.
Early intervention and special educational inputs such as speech therapy and language development programs can help boys who have Klinefelter’s syndrome to perform well academically. Taking the hormone testosterone regularly may help men in developing masculine features. It may have to be taken throughout life. Other benefits of hormone therapy include increase in bone density, which may prevent fractures. Regular thyroid tests, blood sugar tests, and screening for cancer and lung disease, can help diagnose diseases early, and initiate appropriate treatments to avoid complications.
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Triple X Syndrome (Trisomy X , XXX Syndrome )
Triple X Syndrome, which is also referred to as trisomy X, or XXX syndrome, is a genetic disorder occurring in females due to the presence of three copies of the X chromosome.
Triple X syndrome is not a very common genetic defect. However, girls who are affected usually have lower than normal intelligence, especially with regard to verbal and communication skills. Abnormalities affecting the reproductory system are also common. Irregularities in the menstrual cycles and infertility are common issues. However, many women who have trisomy X have given birth to children who are healthy, both physically and genetically.
Occasionally, some girls may have more than three copies of the X chromosomes. They may have 4 or 5 sex chromosomes. The associated symptoms, both physical defects and intellectual disability, are also more severe in such cases. However, such cases are extremely rare occurrence.
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Noonan’s Syndrome
Noonan’s syndrome is the result of a genetic abnormality. It usually causes several symptoms, including congenital heart defects, short stature, and certain abnormal physical characteristics.
In most cases, Noonan’s syndrome may be an inherited condition, but occasionally, it may result from a spontaneous mutation of genes, even when the parents are not affected. One in every thousand to two thousand five hundred people is found to have this genetic abnormality. Noonan’s syndrome was originally considered the male version of Turner’s syndrome, as the characteristic symptoms are similar. However, the underlying genetic defect which causes Noonan’s syndrome is entirely different from that of Turner’s syndrome. A defective gene in the 12th chromosome is the cause of Noonan’s syndrome, and it can affect both boys and girls.
Webbed neck, ears set low in the head, drooping upper eyelids, and eyes set widely apart in the face, are common external symptoms. The fourth finger, which is usually referred to as the ring finger, is shortened in the affected children. Palate may be high-arched too. Hearing problems and heart and blood vessel problems are also prevalent. Short stature is typical of those who have Noonan’s syndrome. In some cases, intellectual disability also may be present. In boys, undescended or underdeveloped testes are common. Underactive or non-functional ovaries may occur in girls. Delayed puberty, and infertility, especially in affected men, is usual.
Hormone therapy is the treatment of choice for Noonan’s syndrome. Initially, the affected child is given growth hormones to improve physical growth. When the child reaches satisfactory physical growth, testosterone is administered if the testes remain underdeveloped. Testosterone is a male sex hormone which would help enhance the development of male characteristics. This treatment has a parallel in the hormone treatment of girls with Turner’s syndrome who are given the female sex hormone estrogen to help attain sexual maturity.
Children who have Noonan’s syndrome require regular hearing tests and screening for probable heart problems.
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Turner’s Syndrome
Turner’s syndrome, also referred to as gonadal dysgenesis, can occur in girls as a result of partial or complete missing of an X chromosome.
- One chromosome from the two X chromosomes normally found in a female may be partially formed or completely deleted in those with Turner’s syndrome.
- Short stature, extra skin at the back of the girl’s neck, and not reaching puberty normally, are the usual symptoms. Learning disabilities are also common in the affected girls.
- A blood test to analyze the chromosomes can confirm the diagnosis.
- Hormone treatments can stimulate normal growth, and help the girls reach puberty.
The pair of X chromosomes in girls is also referred to as sex chromosomes. Turner’s syndrome is the most commonly occurring X chromosome defect in girls. However, occurrence of this condition in live births is very rare due to spontaneous abortion of 99% the affected female fetuses.
Lymphedema, or swellings on the back of hands and top of feet, are common in newborn girls who have Turner’s syndrome. A swelling or extra skin folds may be present at the back of the infant’s neck too. Certain abnormalities like webbed neck, in which extra wide skin connects the shoulders and the neck, also may develop. The chest may be broad with the nipples widely spaced. Girls with Turner’s syndrome are comparatively shorter than other members of their family. The hairline running low at the back of the child’s neck, droopy upper eyelids referred to as ptosis, moles known as nevi, as well as poorly formed nails, may occur in the affected girls, but they are not as common.
Girls who have Turner’s syndrome do not undergo normal sexual development. Breasts, as well as external genitalia such as the labia and the vagina, remain unchanged and child-like, without going through the usual changes associated with puberty, and the girls do not reach menarche. They are usually infertile and do not menstruate as their ovaries do not carry viable eggs. The absence of menstruation is termed amenorrhea. Girls with this condition are almost always obese with a short stature.
Other associated disorders include heart defects, diabetes mellitus, kidney defects, and thyroid disease. Narrowing of a portion of the large blood vessel aorta, known as coarctation of the aorta, is very common. Hemorrhage due to abnormal intestinal blood vessels may occur. Loss of hearing also may occur. Common eye problems include strabismus, commonly known as crossed eyes, and hyperopia or farsightedness. Girls who have Turner’s syndrome are more prone to developing celiac disease also.
ADHD or attention deficit hyperactivity disorder and learning disabilities are common in girls who have Turner’s syndrome. They may have difficulty in assessing spatial and visual relationships. It may be challenging for them to plan different tasks, pay attention, and focus on activities. However, they do not usually have any intellectual disability or mental retardation. They usually perform poorly in mathematics and certain other performance assessments, in spite of their average, or even above average performance in verbal intelligence assessments.
Abnormalities in the appearance of a newborn girl may indicate Turner’s syndrome, but the condition may often go unrecognized till the girl reaches teenage, when the short stature and the lack of sexual development may lead to diagnosis. Further testing to analyze the chromosomal make up help confirm it.
If the affected girl is treated with growth hormones, it can stimulate the girl’s normal growth. Treatment with the hormone estrogen is usually initiated when the girl is around 12 to 13 years old. It can help the child reach puberty. In addition to the sexual maturity attained, there are several other benefits to estrogen therapy, including significant improvement in cognitive development. The ability to focus attention, and plan different tasks, is greatly improved. Assessment of spatial and visual relationships is also enhanced. However, hormone treatment with estrogen is initiated only after satisfactory physical growth is achieved.
Regular eye examinations, preferably by a qualified pediatric ophthalmologist, as well as periodic hearing tests, in addition to frequent assessment of thyroid function, are essential. Timely medical intervention is also necessary to maintain quality of life. Testing for celiac disease is also important.
Watch This Personal Experience About Turner’s Syndrome:
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What Is Fragile X Syndrome
What Is Fragile X Syndrome ?
Fragile X syndrome, caused due to defective DNA in the X chromosome, may result in developmental delays, and intellectual disability, among other symptoms.
The DNA on the X chromosome may have abnormalities which result in the symptoms associated with fragile X syndrome. Since the sex chromosome of boys have XY configuration with the X coming from the mother, they inherit the fragile X syndrome invariably from mothers. Girls have two copies of the X chromosome, one received from the father and the other from the mother. The effect of the fragile X is lesser in girls than in boys as girls have a healthy copy of X chromosome to compensate.
This genetic abnormality causes symptoms such as delayed development and intellectual disability in the affected children. Fragile X syndrome in boys is found to be responsible for most cases of mental retardation resulting from a genetic defect. However, many affected children have normal intellectual development. They usually have large ears which protrude outward; their forehead and chin are usually prominent too. Other typical symptoms include overly flexible joints and a tendency for mitral valve collapse and autistic behavior. These symptoms are more severe in boys than in girls. Boys may have large testes too, but it may become apparent only after they reach puberty. Women who have fragile X may reach menopause earlier than normal, usually around 35 years of age.
Genetic testing can detect the defective DNA indicative of fragile X syndrome. Testing can be done even before birth. Early detection facilitates early intervention. With appropriate treatments, which may include drug therapy with anti-anxiety drugs, antidepressants and stimulants, as well as occupational therapy and language therapy, a better outcome can be expected.
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Babies With Down Syndrome (Trisomy 21; Trisomy G)
Down syndrome, which is also known as trisomy G or trisomy 21, occurs due to a chromosomal defect which results in several physical abnormalities as well as intellectual disability and growth retardation.
- Occurrence of an extra chromosome, particularly three copies of the 21st chromosome, is the most common cause of Down syndrome.
- Short physical stature, typical structural abnormalities in the face and the head, retardation of physical, mental and intellectual development, are the common symptoms of babies with down syndrome.
- The typical physical abnormalities in the newborn often lead to diagnosis, which is confirmed by a blood test to detect the extra chromosome 21in the infant.
- In most cases, children who have Down syndrome reach adulthood.
Normally, one copy each of every chromosome is received from the father and the mother to make up the genetic configuration of the infant. Having an extra chromosome, which results in three copies of the same chromosome, is referred to as trisomy. Among the different types, the most commonly occurring trisomy is Trisomy 21, which is the usual reason for Down syndrome, accounting for almost 95 % of cases. In most cases, two out of the three copies of the 21st chromosome may have come from the father. But, mothers older than 35 years are highly prone to contribute this extra chromosome to the infant. However, since most of the births take place in women of a younger age, infants born with this condition to mothers 35 and older, account for only 20 percent of the overall statistics. Mothers with Down syndrome typically have 50 percent probability of giving birth to an infant with the same condition. But spontaneous abortion of fetuses with this abnormality is very common. On the other hand, men who have Trisomy 21 are generally not fertile.
Symptoms
Delayed mental, as well as physical development is a characteristic symptom of babies with Down syndrome. As infants, they are usually quiet, and cry very rarely. Their limp muscles and quiet nature cause them to be described as passive and placid babies. The head is usually small, with a flat and broad face and characteristic slanting eyes. The nose is short; ears are also small and rounded, often situated lower in the head than normal. A large tongue, extra skin folds at the back of the neck, and short but broad hands having only one crease running across the palm, are typical. Hands have short fingers, with the little finger curved inward and often having only two sections instead of the normal three. There is extra space separating the first and second toes. Short stature is also typical of children as well as adults who have Down syndrome. In some cases, these typical abnormalities may not be apparent in the newborns, but they develop gradually.
The average IQ or intelligence quotient of children having Down syndrome is around 50. It may vary greatly between individuals, but still, it may be significantly lower when compared to the average IQ of normal children which is around 100. The listening skills of children who have Down syndrome is usually lower too, which affect the development of language skills. However, visual motor skills are comparatively better, which may make them good at drawing. Attention deficit disorder is common in these children, sometimes along with hyperactivity. Children who have severe intellectual impairment may display autistic behavior patterns. In adults, as well as in children, depression is commonly encountered. Educational and social support, provided early in life, may significantly improve the life and functioning of those who have Down syndrome.
Many heart defects are usually present in babies with Down syndrome. Due to recurrent ear infections and resultant fluid accumulation in the inner ear, they may develop a condition termed serous otitis, which cause hearing difficulties in them. They are at higher risk of developing problems with their vision too, due to the defects in their lenses and corneas. Their neck joints are often unstable, and it may lead to complications such as weakness or even paralysis. Heart disease and thyroid disease may develop in some individuals. Higher risk of blood cancer, or leukemia, is often a cause for the higher mortality rate in children with Down syndrome.
Diagnosis
An ultrasound scan taken during the latter part of pregnancy usually detects the defects associated with Down syndrome. It can be detected much early in pregnancy by a blood test which may show higher levels of certain proteins in the pregnant mother’s blood. This test can be conducted in the initial fifteen to sixteen weeks. Though pregnancy after 35 years of age is known to carry a higher risk of Down syndrome, they account for only twenty out of hundred cases. Hence, all pregnant women, irrespective of their age, are advised to undergo screening for this condition before they reach the 20th week of pregnancy.
Babies with Down syndrome have the characteristic physical appearance which leads to immediate diagnosis of the condition. It can be confirmed by testing a sample of the newborn’s blood to detect abnormalities of the chromosome 21 such as trisomy 21. On confirming the diagnosis, further investigations with ultrasound scans and other specialized blood tests are conducted to determine the extent of abnormalities which may occur as a result of this chromosomal aberration. Detecting associated abnormalities early and treating them appropriately can prevent further deterioration of health. Periodic screening of children with Down syndrome, for the development of thyroid disease as well as hearing and vision problems, is necessary. Instability of the neck joints should be assessed by x-ray analysis before they can be trained in sports to participate in events such as Special Olympics.
Prognosis
Babies with Down syndrome usually have a faster rate of aging, but most of them reach adulthood. The average lifespan of people with Down syndrome is found to be around 49 years, but many live beyond that and even up to 60 years or more. Many complications like memory loss, cognitive impairment and changes in personality, usually associated with aging-related ailments such as Alzheimer’s, begin to appear earlier in life than they normally appear in the general population. Majority of the children who do not survive into adulthood usually die of leukemia or heart disease. Most defects of the heart can be treated with medication or corrective surgery for a better outcome.
In some recent studies, whites who have Down syndrome are found to live longer than blacks who have the same condition. More than genetic disposition, these findings may point to the fact that, better medical care, as well as social, and educational support, can significantly improve the life span of people with Down syndrome.
Watch This !! What is Down Syndrome? The Facts and Myths Explained