No association between HOXA1 and HOXB1 genes and autism spectrum disorders (ASD)
- 1Section of Medical Genetics and Molecular Medicine, Children’s Mercy Hospitals and Clinics, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri, USA
- 2University of Missouri School of Medicine, Columbia, Missouri, USA
- Correspondence to: Dr M G Butler, Section of Medical Genetics and Molecular Medicine, Children’s Mercy Hospitals and Clinics, 2401 Gillham Road, Kansas City, MO 64108, USA;
Autism (MIM 209850) is an early onset neurodevelopmental disorder with a prevalence rate of at least 5 in 10 000 people1–3 and belongs to a group of heterogeneous diseases known as autism spectrum disorders (ASD), including autism, Asperger syndrome, and the prototypical pervasive development disorder-not otherwise specified (PDD-NOS).4 Affected subjects have impairment in reciprocal communication and social interaction which are accompanied by repetitive and stereotyped behaviours and interests.
Twin and family studies have shown a strong underlying genetic predisposition for autism5–8 with linkage to regions 2q, 7q, 16p,9–12 and 15q.13–15 The greatest linkage is to 7q31.9,16,17 However, to date no single gene has been identified as being responsible for autism and it is suggested that as many as 15 loci are likely to contribute to its aetiology.18,19
Because autism is a neurodevelopmental disorder, genes involved in early formation of the brain and nervous system are good candidates to study for this complex disorder. HOX genes encode a class of transcription factors known as homeobox genes which are involved in regulating neural migration during embryogenesis.20,21 Furthermore, analysis of mice mutants have shown that HOX genes, specifically HOXA1 and HOXB1, function together in the development of the hindbrain.22,23HOXA1 and HOXB1 are located on chromosomes 7p24,25 and 17q25 in humans, respectively.
Recently, Ingram et al26 investigated the frequency of HOXA1 and HOXB1 variants in 57 white autistic probands from singleton or multiplex families and 119 unrelated adults as controls. They studied a variant of the HOXA1 gene (A218G) which changes the codon for one histidine in a series of histidine repeats to an arginine (H73R). They also studied a common variant in the HOXB1 gene which includes a 9 …