Duane-radial ray syndrome

The Okihiro syndrome - also known as (English ) Duane - radial ray syndrome ( DRRS ) called - is an autosomal dominantly inherited combination of malformations.

Symptoms

Are characteristic malformations of the upper limbs (almost identical with those in Holt- Oram syndrome) in combination with a Duane anomaly, a special form of strabismus in which one can not see outside. The limb malformations affecting the thumb ( tripartite thumb, underdeveloped ( hypoplastic ) fingers crossed, but in contrast to the Holt -Oram syndrome and supernumerary thumb ( preaxial polydactyly ) ), and usually occur together with abnormalities of the radius ( spoke) on. However, the arms can be shortened to a phocomelia.

In addition, are often kidney malformations and / or a wrong position of the kidneys. Hearing disorders were first described as characteristic, but is found in only about 19% of those affected. Ear malformations and Fußfehlbildungen occur. Heart defects are also not uncommon here septal and ventricular septal defects frequently. Some children with Okihiro syndrome are short stature due to growth hormone deficiency. Occasionally, are facial asymmetry. Even an anal atresia can occur.

The syndrome occurs relatively infrequently, the average occurrence probability is a maximum of 1:100,000. where it occurs sporadically in the majority of cases due to a new mutation ( lie here so far no figures ).

Cause

Cause of Okihiro syndrome are genetic mutations in the gene ( hereditary factor ) SALL4 on chromosome 20 Genlocis q13.13 - 13.2, which are associated with the syndrome found in about 90 to 95 % of people.

The Okihiro syndrome can be confused with thalidomide ( thalidomide ) embryopathy. This was the cause of rare reports of people having adopted thalidomide malformations, the children were given the same malformations, such that ( but only by a few doctors ) a erbschädigende ( mutagenic ) effects of thalidomide ( thalidomide ) has been claimed. Through the detection of genetic defects in SALL4 with these people and their children could be shown that the malformations in them were not caused by thalidomide and thalidomide malformations not caused by a mutagenic effect of the drug.

It is important to distinguish it from the Holt -Oram syndrome (caused by peculiarities in the gene TBX5 on chromosome 12). Here, the same Armfehlbildungen are ( with the exception of supernumerary thumb, which the Holt -Oram syndrome - if at all - only extremely rarely are ), and heart failure. About 80 % of people with Holt- Oram syndrome have cardiac arrhythmias, which are not known in Okihiro syndrome. Lying next to the heart and limb malformations are other malformations ago, a Holt -Oram syndrome is almost impossible.

The Okihiro syndrome may also be confused with the Townes - Brocks syndrome, which is caused by defects in the gene SALL1 similar to chromosome 16. The syndrome is characterized by ear malformations, thumb malformations (as in Okihiro syndrome) and anal atresia. The radius is not reduced in this syndrome. However, rarely present a Duane anomaly also in Townes - Brocks syndrome.

Other features with very similar symptoms are the thrombocytopenia - absent- radius syndrome ( TAR) (here, the thumbs are always preserved, but the radius is always missing and the platelet count is lower than usual) and Fanconi anemia ( here is a special fragility the chromosomes as well as a tumor inclination).

Forecast

The life expectancy of people with Okihiro syndrome is not reduced in general. Therapeutic importance of the correction of the most mild heart failure as well as corrections of malformations of the extremities and strabismus surgery for the treatment of Duane anomaly. Renal function should be monitored, but kidney dysfunction are rare. When suspected Okihiro syndrome, a hearing test should be made early.