Changes

==Diagnosis==

==Diagnosis==

The diagnosis of SCID is based on three criteria; a) persistent lymphopaenia with less than 1000 lymphocytes per ml, b) lack of serum IgM in foals over four weeks of age and c) lymphoid hypoplasia. Diagnosis is often difficult and post mortem examination may be required. Post mortem findings of a small thymus and/or absent lymph nodes combined with the presence of opportunistic infections support a diagnosis of SCID. Histologically, lymph node follicles and germinal centres are absent.  

The antemortem diagnosis of SCID is based on three criteria; a) a persistent lymphopaenia with less than 1000 lymphocytes per ml, b) a lack of serum IgM in foals over four weeks of age and c) lymphoid hypoplasia. Blood or cheek swabs may be submitted for PCR to identify the mutant allele of the DNA-PK gene in order to obtain definitive diagnosis. The test also identifies carriers of the disease which is important for screening prior to breeding. Additionally, post mortem findings of a small thymus and/or absent lymph nodes combined with the presence of opportunistic infections support a diagnosis of SCID. Histologically, lymph node follicles and germinal centres are absent with severe cellular hypoplasia of the thymus and lymph nodes.

==References==

==References==

*McClure, J. T. (1997) '''New Developments in Severe Combined Immunodeficiency Disease''' ''Proceedings of the Annual Convention of the AAEP (43) pp61-64''

*McClure, J. T. (1997) '''New Developments in Severe Combined Immunodeficiency Disease''' ''Proceedings of the Annual Convention of the AAEP (43) pp61-64''