Phocomelia syndrome (PS) is a rare birth defect that causes severe birth defects, especially of the upper limbs. The bones of the arms, and in some cases other appendages, may be extremely shortened and even absent. The fingers of the hands may be fused. An extreme case results in the absence of the upper bones of both the arms and legs so that the hands and feet appear attached directly to the body. This is called tetraphocomelia.
This disorder, PS, may be genetically transmitted within families as an autosomal recessive trait or may be the result of spontaneous (sporadic) changes in the gene. Because the signs of the disorder so closely mimic those caused by the ingestion of thalidomide by pregnant women, the term "pseudo-thalidomide" is frequently used.