Abstracts

Recently, familial forms of bilateral perisylvian polymicrogyria (BPP) have been described and a candidate locus was mapped on chromosome (ch) Xq28, distal do marker DX8103. The objective of this study was to describe clinical and linkage analysis in 3 families segregating BPP and to establish genotype-phenotype correlations. We studied 3 unrelated families segregating BPP. A total of 26 individuals, including 14 patients were evaluated in this study. All family members were examined by a neurologist and subjected to high resolution volumetric MRI scans with multiplanar reconstruction. Family members were genotyped for 6 polymorphic dinucleotide repeat markers: DXS1192, DXS1227, DXS8043, DXS8091, DXS8103, and DXS1073, flanking a 10 cM interval on ch Xq27-q28. Two-point lod scores were calculated for all families combined using the LINKAGE package. Clinical spectrum ranged from normal to mild neurological dysfunction, mainly pseudobulbar paresis, such as poor articulation and poor tongue movements. All 14 patients had BPP confirmed by MRI, in different anatomical distributions: 9 patients had only BPP, 3 had posterior parietal BPP and 2 had frontoparietal BPP. Linkage analysis yield a Zmax = 3.01 at [Theta]=0.00 for DXS8091. Haplotype analysis showed two critical recombination events that place the candidate interval within a 21.6 cM region between markers DSXS1227 and DX8091. Our results point to a different candidate region on ch Xq in familial forms of BPP. In addition, our data places the candidate interval to a 21.6 cM region mapped to Xq27-q28, a more centromeric location than previously reported. (Supported by CNPq and FAPESP.)