Craniofacial anomalies — Oculo-auriculo-vertebral spectrum, Hemifacial microsomia, Goldenhar syndrome
The following three conditions are believed by many to be related to each other and may be part of the same variable disorder.
Oculo auriculo vertebral spectrum, or OAVS (Oculo refers to the eye, auriculo to the ear, and vertebral to the spine.) As the name suggests, this spectrum involves the eye, ear, and spine. The problems with the eye, ear and spine are the same as those described for hemifacial microsomia and Goldenhar Syndrome. Like Goldenhar Syndrome, one side of the face is usually affected, but 10-33% have both sides affected. Just like in Goldenhar syndrome, those with both sides of the face affected usually have one side that is more severely affected than the other side. OAV spectrum encompasses both hemifacial microsomia and Goldenhar syndrome. It is thought that Goldenhar Syndrome may be a more complicated version of OAV while hemifacial microsomia may be a milder version. It is possible that someone with just a small ear, and no other problems, may be at the very mildest end of this spectrum.
Hemifacial means one side of the face. Microsomia means small. Hemifacial microsomia means that one side of the face is smaller than the other side.
Hemifacial microsomia tends to affect the right side of the face about 60% of the time. The reason why this side is more often affected than the left is not known. The jaw on the affected side may be smaller, as well as the eye. The cheekbones may not be as well developed, making the cheek on the affected side look a little flatter. The corner of the mouth on the affected side may be extended. The outer ear may be smaller (microtia), or in some cases absent (anotia). There may be extra bits of skin, called skin tags, or dimples called pits, in front of the ear. It is possible to have some hearing loss. A person with hemifacial microsomia may have all or just a few of these features. Most people with hemifacial microsomia have normal intelligence. Just having a small ear may be at the very mild end of this condition.
People with this syndrome can have all the same features as those with hemifacial microsomia, but somewhere between 10 and 33% of people with Goldenhar syndrome have both sides of the face affected. One side is usually more affected than the other. In addition to the features of hemifacial microsomia, with Goldenhar syndrome the muscles in the mouth and tongue may be weaker and speech therapy is often advisable. Teeth may erupt later than usual and some may be missing. A cleft lip, a cleft palate, or a cleft lip and palate may be present. Cleft palate alone is more common than cleft lip or cleft lip and cleft palate together. About 35% have a dermoid (cyst on the eye), which is usually not harmful and does not impair vision. If a dermoid is going to occur it will be present from birth. There may also be a small notch in the upper eyelid called a coloboma.
In addition to the facial findings, those with Goldenhar Syndrome also have other parts of the body affected. Heart defects can occur, as can differences in the way the kidneys are formed. In some cases one kidney may be absent. A person can live a full life with only one kidney, but it would be advisable to be cautious and avoid contact sports to reduce the risk of injuring the remaining kidney. There may be difference in the spine, such as two bones being fused together. This occurs in 20-35% of people with Goldenhar Syndrome. Most people with Goldenhar Syndrome have normal intelligence.
What causes these problems?
It is thought that a disruption or decrease in blood flow to the affected areas during pregnancy causes the features. It is not known why the blood flow is disrupted or decreased in most cases. It is known that certain medications such as primidone (a type of seizure medication) and too much retinoic acid (vitamin A) taken early in pregnancy can increase the chances of having a baby with these problems. This spectrum is also more common in diabetic mothers. There may also be several genes involved, as well as other unknown non-genetic factors.
Can these problems happen in another child?
In most cases it is sporadic. This means that if it occurred for the first time there is a low risk of it occurring again in any future children. Recurrence risk (chance of it happening again in another child) would be around 2-3%, so in 97-98% it would not occur again. There are cases of identical twins where one twin was affected and the other one was not. Because identical twins have the same genetic information this would indicate that environment must have a very strong role to play in at least some cases.
In a very small number of families, genetics does seem to play a larger role in the occurrence of this disorder. In these families the problems appear to be inherited in either an autosomal recessive or an autosomal dominant manner. The type of inheritance is determined by looking at who is affected in the family and their relationship to one another. Within these families the degree to which different people are affected is also very variable.
Is genetic testing available?
Currently there is no genetic test for this condition. You can have an ultrasound while pregnant: however, this may not detect all the findings associated with this spectrum, particularly if it is very mild.
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