The field of medical genetics is rapidly expanding our knowledge of how genes and chromosomes cause certain disorders and diseases. Genetic disorders are responsible for a variety of birth defects, chronic diseases and a high percentage of mental retardation. Most genetic disorders are difficult to diagnose by someone not trained in medical genetics, but a patient's physical features and personal and family medical history can provide valuable clues that may indicate the presence of a genetic disorder.
For example, the presence in an individual of several unusual physical features can be associated with genetic disorders. Often, these unusual features do not affect any major function of the body or pose any serious cosmetic problem for the patient. Generally, the presence of one or two unusual features is not medically significant. Most people inherit these features from a parent. A particular family may have an unusual feature as a regular occurrence, such as large ears. But an individual who had three or more unusual features that are not present in other family members, may have a genetic disorder.
These features may appear anywhere on the body but are most commonly found in areas of variability; such as the face, hands and feet. The range of normal features and growth characteristics is fairly broad. Accurately evaluating these features and characteristics may require a complete genetic evaluation. Some unusual features would by themselves, indicate the need for a genetic evaluation. These features include microcephaly or small head size, cleft lip or palate, and other severe features.
Let's look at some of the unusual physical features that may indicate a need for a genetic referral. We'll begin with unusual ear characteristics such as ear pits or small depressions near the ear, ear tags or bits of cartilage positioned near the ears, unusual shape size or positioning of the ears, in which the ears may be set too high or too low or rotated from the normal vertical position.
Unusual eye characteristics including down-slanting or up-slanting eyes, epicanthal folds which are layers of skin that cover the inner corners of the eyes, wide spaced eyes, protruding eyes or proptosis, cataracts, glaucoma and nystagmus or unusual eye movements or squint.
Unusual facial features including coarse features, facial asymmetry, very small jaw or micrognathia in non-infants, crooked skull or plagiocephaly, an unusual skull shape or craniosynostosis.
Unusual hair characteristics including sparse hair, excessive amounts of body hair or white patch of hair.
Unusual oral or dental features such as protruding tongue, teeth which hae unusual shape or are increased or decreased in number, smooth philtrum or upper lip and cleft lip or cleft palate.
The hands, feet and limbs may also have unusual features such as webbing between the fingers and toes, extra fingers or toes called polidactyly, missing fingers, toes or limbs, loose joints or disproportionate length of limbs through the length of the body. Variation from normal growth parameters such as unusually tall or short stature, abnormal skin characteristics such as having excessive skin, many birth marks with pink, white or brown spots or macules. Other physical conditions or diseases that may indicate the presence of a genetic condition, include congential heart disease, genital malformations, diaphragmatic hernia and congenital joint contractures.
Developmental problems including developmental delay affecting language, motor and social skills, failure to thrive, emotional or mental problems including attention deficit disorder, regression of developmental or learning skills, low or decreased muscle tone and seizures not associated with fear.
An individual's family background or medical history also may indicate the need for a genetic evaluation. Individuals or families who may need referral to a genetic specialist include:
Couple who have had a child born with a birth defect or mental retardation and who may be concerned about having other children with the same condition.
Children with unusual physical features or who may not be developing physically or mentally at the expected rate or who may be losing developmental or cognitive skills.
One or more members of the family with mental retardation or developmental delay with no known cause.
One or more members of the family who have birth defects or metabolic disorders caused by a recognized genetic disorder such as spina bifida, neural tube defects or Down syndrome.
Consanguineous couples of members of the same family who might be concerned about having children.
Individuals who belong to an ethnic or racial group with a high incidence of a specific genetic disease such as Tay-Sachs in the Jewish population and sickle cell anemia in African Americans.
Couples who have more than two miscarriages, a stillbirth, or problems conceiving a child.
Pregnant women who might have been exposed to teratogens which are substances that can harm an unborn baby, including alcohol, drugs, tobacco smoke, viruses and other agents.
Pregnant women over the age of 34 who are concerned about the increased age related risk to the unborn child.
Children who are being placed for adoption.
Individuals with unexplained or familial loss of hearing or vision.
Individuals with chronic diseases including hemoglobinopathies, bleeding disorders and cystic fibrosis.
If you have a patient that you feel needs a referral to a genetic specialist, you may call 1-800- 422-2956 or your local health department clinic, to find a medical genetic service provider in your area.
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