[ARX mutations and mental retardation of unknown etiology: three new cases in Spain].
BACKGROUND
Mental retardation has an approximated prevalence of 2% in the general population and its most frequent cause is X-fragile syndrome. This genetic disorder predominantly affects males and it is mainly caused by the expansion of CGG in FMR1 gene. Recently has been demonstrated that mutations in a new called ARX gene (aristaless-related homeobox) can also cause a similar form of X linked mental retardation, as well as other neurological disorders (autism, Partington or West syndrome). The most frequent mutation that has been reported is the c.428_451 dup24, which comprises almost 60% of all described. It causes an expansion of a polyalanine tract of ARX protein.


METHODS
We report three cases of mental retardation in two different families where the mutation in ARX gene c.428_451 dup24 was found while X-fragile syndrome screening was made. Personal and familiar history, phenotype and evolution are described.


CONCLUSIONS
The molecular analysis of this mutation should be considered as a routine for the genetic diagnosis of mental retardation in males of nondrafted cause.
Romero-Rubio
M T
MT
Hospital Clínico Universitario, Valencia, España. romerorubio@hotmail.es
Andrés-Celma
M
M
Castelló-Pomares
M L
ML
Roselló
M
M
Ferrer-Bolufer
I
I
Martínez-Castellano
F
F
D002675:Child, Preschool; D005260:Female; D005600:Fragile X Syndrome / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D007223:Infant; D008297:Male; D038901:X-Linked Intellectual Disability / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics*; D009154:Mutation; D010375:Pedigree; D013030:Spain / Q000453:epidemiology; D014157:Transcription Factors / Q000235:genetics*
C469264:ARX protein, human; D018398:Homeodomain Proteins; D014157:Transcription Factors