Abstract
Restriction fragment length polymorphisms (RFLPs) are useful in linkage and clinical association studies of human diseases. In this report, we characterize the molecular basis and frequencies of two new RFLPs, AvaII and BalI, two previously reported RFLPs, HincII and PvuII, and one new sequence polymorphism in the human apolipoprotein B gene. For the AvaII RFLP, the two alleles yield either a 1 kb fragment or 0.7 and 0.3 kb fragments, and have frequencies of 20% and 80%, respectively. The polymorphic site is about 4 kb upstream of exon 1. For the BalI RFLP, the two alleles yield either a 4.9 or 6.2 kb fragment, and have about equal frequencies. The polymorphic site is within an Alu sequence in intron 20, 146 bp 5' to exon 21. The BalI recognition sequence TGGCCA is replaced by TAGCCA. For the HincII RFLP, the two alleles yield either a 1.7 or 1.3 kb fragment and have frequencies of 80% and 20%, respectively. The polymorphic site is in intron 4, 171 bp 3' to exon 4. The HincII recognition sequence GTTAAC, present in the minor allele, is replaced by GTTACC. HincII fragments of 7.4 and 7.0 kb, previously reported for this polymorphism, are the result of partial digestion at the invariant HincII site in intron 3, 334 bp 3' to exon 3. For the PvuII RFLP, the two alleles yield either a 7.5 or 5.5 kb fragment and have frequencies of 96% and 4%, respectively. The polymorphic site is within an Alu sequence in intron 4, 523 bp 5' to exon 5.(ABSTRACT TRUNCATED AT 250 WORDS)
Highlights
Restriction fragment length polymorphisms (RFLPs) are useful in linkage and clinical association studies of human diseases
We have shown that an unequal crossing over between the Alu sequences in introns 20 and 21 resulted in the deletion of exon 21 from the Apolipoprotein B (apoB) gene of a patient with homozygous hypobetalipoproteinemia [9]
The four remaining RFLPs result in amino acid changes in the protein and correspond to four of the five Ag allotypes defined by antisera [14,15,16,17]
Summary
Restriction fragment length polymorphisms (RFLPs) are useful in linkage and clinical association studies of human diseases. We characterize the molecular basis and frequencies of two new RFLPs, AvaII and BalI, two previously reported RFLPs, HincII and PvuII, and one new sequence polymorphism in the human apolipoprotein B gene. For the sequence polymorphism in intron 3, the alleles have either a G or T at the position 92 bp 3' to exon 3 and have frequencies of 53% and 4776, respectively.-Huang, L-S., M. Recent studies have identified mutations in the apoB gene that alter plasma LDL-cholesterol levels [6,7,8,9]. I n addition to these mutations, common genetic variation in the apoB gene detected as restriction fragment length polymorphisms (RFLPs) has been reported [4, 10,11,12,13]. We elucidated the molecular basis of two previously reported RFLPs (ll), HincII and PvuII
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