NEURAL BASIS OF AN INHERITED SPEECH AND LANGUAGE DISORDER

Investigation of the three-generation KE family, half of whose members are affected by a pronounced verbal dyspraxia, has led to identificat ion of their core deficit as one involving sequential articulation and orofacial praxis. A positron emission tomography activation study rev ealed functional abnormalities in both cortical and subcortical motor- related areas of the frontal lobe, while quantitative analyses of magn etic resonance imaging scans revealed structural abnormalities in seve ral of these same areas, particularly the caudate nucleus, which was f ound to be abnormally small bilaterally. A recent linkage study [Fishe r, S., Vargha-Khadem, F., Watkins, K. E., Monaco, A. P. & Pembry, M. E . (1998) Nat. Getter. 18, 168-170] localized the abnormal gene (SPCH1) to a 5.6-centiMorgan interval in the chromosomal band 7q31. The genet ic mutation or deletion in this region has resulted in the abnormal de velopment of several brain areas that appear to be critical for both o rofacial movements and sequential articulation, leading to marked disr uption of speech and expressive language.