PRENATAL DIAGNOSIS OF X-LINKED SEVERE COMBINED IMMUNODEFICIENCY (SCID) BY FLOWCYTOMETRIC INVESTIGATION OF FETAL BLOOD

Abstract

Prenatal diagnosis of SCID has until now been limited due to the inability of obtaining sufficient fetal blood volumes for immunological investigation. - We report the diagnosis of x-linked SCID at 19 weeks of gestation by using 200μl fetal blood for flowcytometrio evaluation. Amniocentesis was performed in the 17th week of pregnancy on a 36 year old woman with positive family history for X-linked SCID. chromosome analysis revealed a normal male caryotype. To confirm the suspected diagnosis of SCID a fetal blood sample was taken by puncturing the umbilical cord vein under sonographic control at 19 weeks of gestation. 300μl were used to perform chromosome analysis, the remaining 200μl were prepared for flowcytometry. Whole blood was stained with a combination of phycoerythrin and fluorescein-conjugated monoclonal antibodies to leukocyte surface antigens (Leu2, Leu3, Leu4, Leu7, LeuM3, HLA-Dr). Simultaneous two color flowcytometric analysis showed virtually no T-cells consistent with a diagnosis of SCID. Pregnancy was interrupted and the diagnosis confirmed after fetal autopsy. - Our data demonstrate that flowcytometry provides a reliable tool for early prenatal diagnosis of immunodeficiencies requiring minimal blood samples.