Dosis génica y lenguaje: a propósito de la región cromosómica 7q11.23

Molecular characterization of genomic disorders in which language impairment is a prominent symptom decisively contributes to a better understanding of the effect of gene dosage on the development of the language organ. One of the most well-characterized deletion/duplication syndromes concer chromosome 7q11.23. The common recurrent microdeletion/microduplication affects to a critical region of 1.5 Mb. When this region is deleted (Williams-Beuren syndrome), language, but not other cognitive abilities, seems to remain intact. Conversely, when this region is duplicated, a severe delay in expressive speech emerges. The 1.5 Mb region is estimated to encompass nearly thirty functional genes, some of which have been tentatively linked to differer of the cognitive and linguistic pecualiarities of the syndromes. A change in gene dosage has also been confirmed for some of these genes. The phenotypic and molecular analysis of other similar genomic disorders (like chromosome 22q13.3 deletion syndrome or Potocki-Lupski/Smith-Magenis syndromes) clearly suggests that not only gene sequences, but also transcriptional profiles of the different genes involved, decisively shape the innate programme responsible for the development of the language module.