Two-base mutation in

GATA-1 segregates with thrombocytopenia. (A) cDNAs derived from an unaffected male (II-8, father), carrier female (II-7, mother), and affected male (III-9, son) were amplified withGATA-1 oligonucleotides (primer pair 2) and sequenced. The 2 bases mutated in this family (GG to TC) are highlighted in each sequence. (B) Genomic DNA samples from family members were amplified with GATA-1 primer pair 2 then digested with Cel-II endonuclease (recognition site, GCTNAGC). The larger band represents the wild-type allele (I-1, II-8), whereas mutant alleles contain a new Cel-II restriction site resulting in a 65-bp reduction of the largest DNA fragment (II-5, II-4, III-9). The presence of 2 bands (II-7) indicates carrier status with both alleles.