Holt–Oram syndrome
Holt -Oram syndrome
The Holt -Oram syndrome - also known as atriodigitale dysplasia - one of the so-called heart -hand syndromes. It is an autosomal dominant feature on the basis of a genetic mutation caused by malformations of the thumb or the spoke ( club hand ) and the heart ( atrial septal and ventricular septal defects often ) is characterized. First description was in 1960 by the British pediatrician Mary Holt and Samuel Oram cardiologists.
Frequency of occurrence
The syndrome occurs relatively infrequently, the average probability of occurrence is approximately 1:100,000, and it sporadically occurs in 85 % of cases due to a new mutation.
Cause
Cause of Holt- Oram syndrome is caused by genetic mutations in the gene locus 12q23 - 24.1 ( TBX5 ) on chromosome 12 that are associated with the syndrome found in 30 to 70 out of 100 people. Probably also features in other genes can cause the same symptoms
Differential Diagnosis
The Holt -Oram syndrome is often misdiagnosed. It is important to distinguish it from the Okihiro syndrome (caused by peculiarities in the gene SALL4 on chromosome 20). Here are the same Armfehlbildungen and occasionally heart defects. But people with Okihiro syndrome often show a Duane anomaly, ie, a special form of strabismus in which one can not see outside, kidney malformations and / or a wrong position of the kidneys, plus hearing disorders, ear malformations and also Fußfehlbildungen.
Other features with very similar symptoms are the thrombocytopenia - absent- radius syndrome (TAR ) ( here the thumbs are always obtained, but the radius is missing and the platelet count is lower than usual) and Fanconi anemia ( here is a special fragility of chromosomes as well as a tumor inclination).
Forecast
The life expectancy of people with the Holt- Oram syndrome is not reduced in general; and it is important here, especially on the nature and treatability of the heart defect. Therapeutic significance of the correction of the heart defect and correction of deformities of the limbs.