(A) PCR analysis of the type I deletion.
Lanes 1–4, biplex PCR of exons 11 and 12; lanes 5–8, biplex PCR of
exons 31 and 32. The type I homozygotes in lanes 1, 2, 5, and 6 lack
exons 12 and 31; lanes 3, 4, 7, and 8 are normal controls.
(B) Sequence analysis of the type I deletion breakpoint.
IVS11 and 31 show experimentally determined sequences from introns 11
and 31 in a 5′ to 3′ direction. The sequence determined from the type 1
breakpoint PCR product is shown between the intronic sequences. The
dotted box shows homology between IVS11 sequence and the 5′ end of the
type 1 sequence. The dashed box shows homology between the type 1
sequence and IVS31. The overlap between these two regions of homology
is the likely recombination site. The double-underlined italic bold
motif in the type 1 sequence was found to be highly homologous to
Alu repeat sequences of various subfamilies. An
unidentified nucleotide is designated N in the IVS31 sequence.
(C) PCR analysis of the type I deletion. The larger
product is a 1.3-kb fragment amplified from exons 12–14 of the
wild-type FANCA gene, and the smaller product is the
715-bp fragment from the type I deletion. Lanes 1, 2, 5, and 8, type I
heterozygotes; lanes 6 and 7, controls; lanes 3 and 4, type I
homozygotes.