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.
What are the characteristic features and symptoms of Down syndrome?
Although the severity of Down syndrome ranges from mild to severe, most
individuals with Down syndrome have widely recognizable physical
characteristics. These include:
a flattened face and nose, a short neck, a small mouth sometimes with a
large, protruding tongue, small ears, upward slanting eyes that may have
small skin folds at the inner corner (epicanthal fold);
white
spots (also known as Brushfield spots) may be present on the colored part of the
eye (iris);
the hands are short and broad with short fingers, and with a single
crease in the palm;
poor muscle tone and loose ligaments are also common; and
development and growth is usually delayed and often average height and
developmental milestones are not reached.
What type of prenatal screening is available for Down syndrome?
Several noninvasive screening options are offered to parents. If Down
syndrome is suspected due to the screening outcome, a formal diagnosis can be
made before the baby arrives. This gives parents time to gather information
about Down syndrome before their baby is born and to make arrangements in case
of medical complications.
Prenatal screening tests currently available include the expanded
alpha-fetoprotein (AFP) screening test, the nuchal translucency test, and
additional ultrasound screens which look for changes in certain anatomical
features of the fetus. While these screening tests can assess the risk for Down
syndrome, they cannot confirm Down syndrome with certainty.
The most widely used screening test is the AFP. Between weeks 15 and 20 of
pregnancy, a small blood sample is taken from the mother and examined. The
levels of AFP and three hormones called unconjugated estriol, human chorionic
gonadotropin, and inhibin-A are measured in the blood sample. If the AFP and
hormone levels are altered, Down syndrome can be suspected, but not confirmed.
Likewise, a normal test result does not rule out Down syndrome.
The nuchal translucency test measures the thickness of the fold in the neck
via ultrasound. This test can be done between 11 and 13 weeks of pregnancy. In
combination with the mother's age, this test identifies about 80% of Down
syndrome fetuses.
Women considered at high risk (advanced maternal age, positive AFP test, or a
history of a previous child with Down syndrome) may benefit from additional
ultrasound scans between 18 and 22 weeks of pregnancy. When certain anatomical
features are altered, absent, or present in a fetus, it may indicate Down
syndrome. Some of the markers that are examined include:
the length of the long
arm (humerus) or leg bone (femur),
the length of the nasal bridge,
the size of
the renal pelvis (hypoplasia, pyelectasis),
small bright spots in the heart
(echogenic intracardiac foci),
small middle section of the little finger
(hypoplastic fifth digit),
a large gap between the first and second toe,
increased brightness of the bowel (echogenic bowel), and
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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