Sietske N. Heyn is a medical writer with a PhD in neuroscience. Dr. Heyn's education includes a BS with honors from the University of Oregon, and a doctoral degree in neuroscience from the University of California at Davis. After completing postdoctoral training at the University of California, San Francisco, and many years of working as a medical writer at the Stanford University Center for Down Syndrome Research, Dr. Heyn now runs her own medical writing business.
Dr. Perlstein received his Medical Degree from the University of Cincinnati and then completed his internship and residency in pediatrics at The New York Hospital, Cornell medical Center in New York City. After serving an additional year as Chief Pediatric Resident, he worked as a private practitioner and then was appointed Director of Ambulatory Pediatrics at St. Barnabas Hospital in the Bronx.
The diagnosis of Down syndrome can be made before birth using one of several
diagnostic tests. These tests carry a small risk of miscarriage.
If Down syndrome is suspected after a child is born, a diagnosis can be made
via chromosome analysis.
Amniocentesis is performed between 16 and 20 weeks of pregnancy. During this
procedure, a thin needle is inserted through the abdominal wall and a small
sample of amniotic fluid is taken. The sample is analyzed for chromosome
anomalies.
Chorionic villus sampling (CVS) is done between 11 and 12 weeks of pregnancy.
It involves the collection a chorionic villus cell sample from the placenta
either through insertion of a needle in the abdominal wall or through a catheter
in the vagina. The chromosomes in CVS are analyzed for deviations.
For percutaneous umbilical blood sampling (PUB), fetal blood is taken from
the umbilical cord using a needle inserted through the abdominal wall. The blood
sample is examined for chromosome abnormalities. It is usually performed after
week 18.
What about cognitive impairment in Down syndrome?
The most common condition associated with Down syndrome is cognitive
impairment. Cognitive development is often delayed, and all individuals with
Down syndrome have mild to severe learning difficulties that last throughout
their lives. How the extra chromosome 21 leads to cognitive impairment is not
entirely clear. The average brain size of a person with Down syndrome is small
and scientists have found alterations in the structure and function of certain
brain areas such as the hippocampus and cerebellum. Particularly affected is the
hippocampus, which is responsible for learning and memory. Scientists are using
human studies and animal models of Down syndrome to find out which specific
genes on the extra chromosome 21 lead to different aspects of cognitive
impairment.
Leukemia is a type of cancer of the blood cells in which the growth and development of the blood cells are abnormal. Strictly speaking, leukemia should refer only to cancer of the white blood cells (the leukocytes) but in practice it can apply to malignancy of any cellular element in the blood or bone marrow, as in red cell leukemia (erythroleukemia).
Dementia is a significant loss of intellectual abilities such as memory capacity, severe enough to interfere with social or occupational functioning. There are different criteria classification schemes for dementias such as cortical, subcortical, progressive, primary, and secondary dementias. Other conditions and medication reactions can also cause dementia. Dementia is diagnosed based on a certain set of criteria. Treatment for dementia is generally focused on the symptoms of the disease.
The Eustachian tube is a membrane lined tube that connects the middle ear space to the back of the nose. Problems include partial or complete blockage which can cause popping, clicking, and ear fullness. Allergies, sinus and ear infections, or the common cold can cause this blockage, while altitude changes can cause symptoms in those persons with Eustachian tube problems. Treatment includes several maneuvers (swallowing, chewing gum, yawning etc.), which can be done to improve Eustachian tube function.
Turner syndrome is an inherited chromosomal condition affecting women. Women with Turner syndrome do not have ovarian function, and features of the syndrome include webbed neck, lymphedema of the hands and feet, heart defects, kidney problems, and skeletal abnormalities. The X chromosome is related to Turner syndrome. Treatment focuses on the symptoms of the syndrome.
Fragile X syndrome is the most common inherited form of mental retardation. It's caused by a mutation on the X chromosome. People with Fragile X syndrome suffer from physical, social, emotional, speech, language, sensory, intelligence, and learning impairments. There is no definitive treatment for Fragile X, though there are ways to minimize the symptoms.
Klinefelter syndrome, also referred to as XXY condition, is a genetic disease. Klinefelter syndrome affects mostly males. Symptoms include decreased testosterone levels, development of breasts, wider hips, and infertility. Some men with Klinefelter syndrome have no symptoms. Treatment includes educational, therapeutic, and medical therapy.
Genetic disease is a disorder or condition caused by abnormalities in a person's genome. Types of genetic inheritance include single inheritance (for example, cystic fibrosis, sickle cell anemia, Marfan syndrome, and hemochromatosis), multifactoral inheritance, chromosome abnormalities (for example, Turner syndrome, and Klinefelter syndrome), and mitochondrial inheritance (for example, epilepsy and dementia).
Hirschsprung's disease (Hirschsprung), is a disease of the nerve cells of of the large intestine. The primary symptom of Hirschsprung's disease is constipation. Hirschsprung's disease is diagnosed through barium enema, and treatment is surgery.
Pregnancy planning is important to help prevent exposure of the mother and fetus to potentially harmful medications and substances during the early days, and throughout the pregnancy. Nutritional planning, prevention of birth defects, conditions such as high blood pressure, heart disease, diabetes, and kidney disease need careful monitoring. Gestational diabetes, preeclampsia, and pregnancy induced hypertension are conditions that may arise during pregnancy. Immunizations, inherited disorders, exercise, air travel, intercourse, and birth control are important factors to consider when planning a pregnancy.
Spina bifida is the most common neural tube defect in the United States. There are four types of spina bifida; 1) occulta, 2) closed neural tube defects, 3) meningocele, and 4) myelomeningocele. The cause of spina bifida is not known. Theories include genetic, nutritional, and environmental factors. Lack of folic acid during pregnancy is highly suspected. Symptoms of spina bifida vary from individual to individual. Treatment depends on the type of spina bifida the person suffers.
Microcephaly is a genetic condition where the circumference of the head is smaller than normal due to underdeveloped brain. Microcephaly is caused by genetic abnormalities, or from abuse of alcohol, drugs, infection (for example, German measles or chickenpox), exposure to toxins, or PKU while the mother is pregnant. Symptoms of microcephaly depend upon the severity of the accompanying syndrome. There is not treatment for microcephaly.
Noonan syndrome is a genetic disorder that causes birth defects (congenital malformations) such as short stature, caved-in chestbone, webbing of the neck as well as heart and blood vessel defects. Named after Dr. Jacqueline A. Noonan it is inherited as an autosomal dominant disorder. The Noonan gene (NS1) is on a nonsex (autosomal) chromosome (number 12) and is transmitted from a parent with a 50% probability to boy or girl. Treatment for Noonan syndrome is directed toward the problems that may occur in a given affected individual. The heart defects may require surgical treatment. The expected outcome (prognosis) depends on the extent and severity of the features that are present.
Your health care provider may refer you to a genetic professional. Universities and medical centers also often have affiliated genetic professionals, or can provide referrals to a genetic professional or genetics clinic. Genetic counseling provides patients and family members the tools to make the right choice in regard to test for a disease or condition.
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