A primer pool for amplifying a target sequence of a human HNF-1.alpha. gene, including at least one set of primers or variant primers thereof, each set of primers being identified by two consecutive SEQ ID NOS, the SEQ ID NOS being given as from SEQ ID NO.3 to SEQ ID NO.22, is provided. A target sequence such as the human HNF-1.alpha. gene may be amplified with a high specificity, a high speed, a high sensitivity and a low cost through a multiplex PCR to detect a maturity-onset of diabetes of the young (MODY) 3 associated gene.