GERMLINE RET PROTOONCOGENE MUTATIONS IN 2 TAIWANESE FAMILIES WITH MULTIPLE ENDOCRINE NEOPLASIA TYPE 2A

To elucidate the germline RET proto-oncogene mutations in Taiwanese fa milies with multiple endocrine neoplasia type 2A (Men 2A), we extracte d DNA from peripheral blood leukocytes of 28 members of two families w ith MEN 2A. Oligonucleotide primers for exons 10 and 11 were used to a nalyze the nucleotide sequence of codons 609, 611, 618, and 620 of exo n 10, and codon 634 of exon 11 of the RET proto-oncogene. Two fragment s of genomic DNA were amplified by polymerase chain reaction (PCR). Th e amplified PCR products were separated and purified from primers and free nucleotides in agarose gels, and the expected 187-bp and 234-bp b ands were cut from the gels and sequenced. Thirteen family members in the two MEN 2A kindreds had mutations in codon 634 of exon 11. In kind red 1 (15 members available for this study), a heterozygous codon 634 mutation in nine members and a homozygous codon 634 mutation in one me mber led to the substitution of Phe (TTC) for Cys (TGC). Three members of kindred 2 (13 members available for this study) had a heterozygous base pair change in codon 634, which led to the substitution of Arg ( CGC) for Cys (TGC). In this study, we found two mutation events occurr ing in two MEN 2A kindreds and also discovered a homozygous point muta tion in one woman that led to heterozygous mutations in all of her chi ldren.