The genomic organization of the Fanconi anemia group A (FAA) gene.

Fanconi anemia (FA) is a genetically heterogenous disease involving at least five genes on the basis of complementation analysis (FAA to FAE). The FAA gene has been recently isolated by two independent approaches, positional and functional cloning. In the present study we describe the genomic structure of the FAA gene. The gene contains 43 exons spanning approximately 80 kb as determined by the alignment of four cosmids and the fine localization of the first and the last exons in restriction fragments of these clones. Exons range from 34 to 188 bp. All but three of the splice sites were consistent with the ag-gt rule. We also describe three alternative splicing events in cDNA clones that result in the loss of exon 37, a 23-bp deletion at the 5' end of exon 41, and a GCAG insertion at the 3' portion also in exon 41. Sequence analysis of the 5' region upstream of the putative transcription start site showed no obvious TATA and CAAT boxes, but did show a GC-rich region, typical of housekeeping genes. Knowledge of the structure of the FAA gene will provide an invaluable resource for the discovery of mutations in the gene that accounts for about 60-66% of FA patients.