CuZn superoxide dismutase activity in trisomy 21 by translocation

Pascale GARBER, P.M. SINET, H. JEROME, J. LEJEUNE


Sommaire

Sir,

After the demonstration of gene dosage effect for indophenol oxidose A (IPO-A) [1], i.e. CuZn superoxide dismutase (CuZn-SOD or SOD-1) [2] in trisomy 21, we localized the gene of CuZn-SOD on the segment including the distal part of 21q21 and 21q22.1 [3].

In order to analyse this dosage effect in trisomy 21 by D/G or G/G translocation (centromeric fusion), we measured the red blood cells SOD activity in the following cases of unbalanced translocation . The method we used is described by LavelIe et al [4].

Compared to seventy cases of free trisomy 21 already studied in our laboratory, the gene dosage effect is, as expected, identical in both types of trisomy.

These results are in disagreement with the data published by Kedziora et al. [5] who claimed that IPO-A and SOD-1 activities were not increased in cases of trisomy 21 resulting from a tronslocation D/G or G/G.

We concluded that there is no detectable chromosome position effect on the CuZn-SOD gene activity in trisomy 21 by centromeric D/G or G/G translocation. The gene dosage effect for this enzyme is identical in free trisomy 21 and in trisomy 21 by translocation .

CuZn activity in erythrocytes of trisomics 21 by translocation
CaseAge (years)SexSOD (g/g Hb)
21/1319F1647
21/1410M1865
21/1510M1726
21/2121M1550
21/1410F1653
21/1415M1593
Trisomics 21 by tronslocation (n = 6) 1672 ± 112*
Trisomics 21 with free trisomy (n = 70) 1645 ± 208*
Controls (n = 67) 1107 ± 87*
(* mean ± SD)

Haut

(1) Sichitiu.S., Sinet, P.M. , Lejeune J, , Frezal,J ., Humangenetik 1974, 23, 65.

(2) Sinet P.M., Allard, D., LeJeune,J ., Jerome, H., C.R.Acad. Sci.Paris 1974, 278, 3267.

(3) Sinet, P.M., Couturier, J ., Dutrillaux, B. , Poissonier, H., Raoul, O., Réthoré, M.O., AI|ard D., Lejeune, J., Jérôme, H., Exp. Cell. Res. 1976, 97, 47.

(4) Lavelle F., Puget K., M;chelson,M., C.R. Acad. Sci. Paris 1974, 278, 2695.

(5) Kedziora, J., Bartosz, G., Leyko, W., Rozynkowa, D. Lancet 1979, i, 105.