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Genetic counseling in martin-bell syndrome

Leda Navajas; Carla Rosenberg; Angela M. Vianna-Morgante

Departamento de Biologia, Instituto de Biociências, Universidade de São Paulo, Caixa Postal 11461, 05499 São Paulo, SP, Brasil. Send correspondence to C.R.

ABSTRACT

The X-linked Martin-Bell Syndrome (MBS) is an important cause of mental retardation. The occurrence of normal transmitting males and the high frequency of mentally impaired hetero-zygotes make its inheritance pattern distinctly different from that of other X-linked diseases. Furthermore, although the expression of the fragile X allows the identification of normal MBScarriers, a proportion of them is fra(X)-negative.
In this paper we estimated the risks of affected offspring for fra(X)-negative possible carriers of the MBS gene. These risks were always below 10%.

Keywords: genetic; counseling; martin-bell; syndrome.

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