Splicing mutation in human hereditary analbuminemia.

We have identified a structural defect in the serum albumin gene in human analbuminemia. Sequence determination of 1.1 kilobases (kb) of the 5' regulatory region and of 6 kb across exonic regions revealed a single AG-to-GG mutation within the 3' splice site of intron 6 in the defective gene of an analbuminemic individual. In an in vitro assay on the RNA transcript this mutation causes a defect in splicing of the intron 6 sequence and in subsequent ligation of the exon 6-exon 7 sequences. Using polymerase-amplified genomic DNA and allele-specific oligodeoxynucleotide probes, we have also shown that the sequence of this intron 6/exon 7 splice junction is normal in a different, unrelated analbuminemic individual. Analbuminemia in humans is therefore the result of one of multiple defects in our genome.