RETT-SYNDROME

The Rett syndrome (RS) was first described in 1966 by Andreas Rett,(1 2) who published the first English language account of the condition i n 1977 as ''Cerebral atrophy with hyperammonaemia''.(3) Rett syndrome became better known in English language publications when Hagberg et a l(4) described 35 affected girls in 1983. The incidence or prevalence among females has been estimated as 1 in 10-15 000 (incidence) in Scot land,(5) 1 in 15 000 (prevalence) in Sweden,(6) 1 in 20 000 (prevalenc e) in Dakota, USA,' and 1 in 22 800 (prevalence) in Texas, USA.(8) RS therefore accounts for 2-3% of severe mental handicap(9 10) and perhap s 10% of profound handicap in females. Despite its importance, however , the pathogenesis of RS remains obscure. It is most likely to be an X linked dominant disorder, lethal in hemizygous males, but this is not certain and has been contested.