Four patients from three families with the clinical features of DOOR syndrome 
(onycho-osteodystrophy, dystrophic thumbs, sensorineural deafness, and increased 
urinary levels of 2-oxoglutarate) are the subjects of this report. Our report 
deals with the autosomal recessive form of the disease, wherein the activity of 
2-oxoglutarate decarboxylase (E1(0)) in fibroblasts and white blood cells of the 
patients is decreased. The activity of E1(0) in all patients' fibroblasts and 
white blood cells was significantly lower compared to the controls. This study 
demonstrates for the first time that E1(0) deficiency is an important 
biochemical marker for the autosomal recessive form of DOOR syndrome.