Ectrodactyly-Ectodermal Dyspl... Health Article

Diagnosis

The diagnosis of EEC syndrome can be complex because of the overlap of symptoms with other ectodermal dysplasia syndromes. The diagnosis of EEC syndrome is usually made through a combination of clinical exam, x rays, kidney imaging tests, skin biopsy, and DNA testing.

To make the diagnosis of EEC, a physician must evaluate which ectodermally derived structures are involved and look for physical features that do not develop from the ectoderm. By looking at the specific pattern of defects, it may be possible to make a correct diagnosis, but because of the overlap between other ectodermal dysplasias, it can often be difficult to make a definitive diagnosis based only clinical exam alone. DNA testing and other tests can help aid in the diagnosis.

X rays are often helpful in establishing the diagnosis of EEC syndrome. X rays may be taken of the jaw to look for dental abnormalities, while x rays of the limbs may be done to look for subtle abnormalities that may not be seen with a clinical exam. The presence of dental abnormalities or limb abnormalities would add to the suspicion that a person had EEC syndrome.

Because individuals with EEC syndrome can have kidney abnormalities, it is important to assess their kidney structure. This can be done using an IV pyelogram or ultrasound. The presence of a kidney abnormality would lend credence to the diagnosis of EEC syndrome, but the absence of a kidney abnormality does not rule out the diagnosis as not every person with EEC syndrome has every symptom.

A skin biopsy involves removing a small amount of several layers of skin to examine them under a microscope. In EEC syndrome, the skin cells themselves may be abnormal. In addition, the sweat glands may be abnormal in number or shape.

DNA testing can also be performed on blood samples from children or adults. The presence of a mutation in the p63 gene would confirm the diagnosis of EEC syndrome. Because scientist have not yet found all of the mutations in this gene, the absence of a detectable mutation does not completely rule out the diagnosis.

The diagnosis of EEC syndrome can also be made prenatally (during pregnancy) either by ultrasound (sonogram) or by prenatal DNA testing. Sonograms use sound waves to provide an image of a fetus. The structural abnormalities of EEC syndrome, including cleft lip, kidney abnormalities, and limb abnormalities, can be detected during the second trimester of pregnancy. Because of the overlap in the some of the structural abnormalities of the ectodermal dysplasias, it can be very difficult to definitively diagnose EEC syndrome by sonogram. Other ectodermal dysplsias can look very similar to EEC syndrome on a sonogram. DNA testing can have a role in clarifying ambiguous ultrasound findings.

Prenatal testing can also be done using DNA testing. A sample of tissue from a fetus is obtained by either chorionic villi sampling (CVS) or by amniocentesis. Chorionic villi sampling is generally done between 10 and 12 weeks of pregnancy, and amniocentesis is done between 14 and 18 weeks of pregnancy. Chorionic villi sampling involves removing a small amount of tissue from the developing placenta. The tissue in the placenta contains the same DNA as the fetus. Amniocentesis involves removing a small amount of fluid from around the fetus. This fluid contains some fetal skin cells. DNA can be isolated from these skin cells. The fetal DNA is then tested to determine if it contains mutations in the p63 gene that causes EEC syndrome. Because not all of the mutations causing EEC syndrome have been found, DNA testing is not always definitive and the interpretation of the test results is best done by a genetics professional.