SPECTRIN ORAN (ALPHA-II/21), A NEW SPECTRIN VARIANT CONCERNING THE ALPHA-II DOMAIN AND CAUSING SEVERE ELLIPTOCYTOSIS IN THE HOMOZYGOUS STATE

  • 1 April 1988
    • journal article
    • research article
    • Vol. 71  (4) , 1039-1047
Abstract
We report on spectrin Oran (.alpha.II/21), a new spectrin variant found in an Algerian family. It was characterized by the absence of the spots that classically correspond to the .alpha.II domain using two-dimensional analysis of spectrin limit digests. On the contrary, the abnormal domain was represented by a new set of spots in the 21-Kd and 16-Kd regions, as demonstrated by Western blots using anti-.alpha.II domain polyclonal antibodies. Spectrin Oran (.alpha.II/21) was found in the homozygous state in two children belonging to two separate branches of the family. It yields a severe elliptocytosis. Spectrin self-association was altered. The variant was much more difficult to prove in the heterozygous state, in which it results in no clinical and virtually no morphological symptom. In all four parents involved, however, electrophoretic analysis and Western blots showed the existence of the .alpha.II 21-Kd and 16-Kd peptides. In one parent, who combines spectrin Oran (.alpha.II/21) and the .alpha.II type-2 polymorphism, the two-dimensional spots (52, 39, 34, and 29 Kd) were quantified and appeared reduced by 30%: there was an intermediary decrease of spectrin self-association in this person. In the three other parents, spectrin Oran combined with the .alpha.II type-1 polymorphism. The .alpha.II type-1 spots (46, 35, 30 and 25 Kd) appeared in normal range, and spectrin self-association was normal. Along with previous observations, the present data emphasize the large fluctuations of the .alpha.-variant percentage. Provided spectrin Oran was present in a sufficient proportion, we found an associated alteration of the .beta.II domain (that faces the .alpha.II domain in the spectrin dimer): the .beta.II 65-Kd fragment was reduced and the .beta.II 52-Kd fragment was reciprocally increased.

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