PCNT and microcephaly: In the northern Pakistani microcephaly pedigrees [15, 17], the first pedigree mutation (246T→A, Y82X; n = 8) generates a truncated 81 amino acid peptide that lacks a portion of the SM1 binding motif, the two SMC motifs, the EB1 binding region, and the p35- and pericentrin-binding regions.