Nondetectability of restriction fragments and independence of DNA fragment sizes within and between loci in RFLP typing of DNA

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · American Journal of Human Genetics; (United States)

OSTI ID:7101385

Chakraborty, R; Zhong, Y; Jin, L ^[1]; Budowle, B ^[2]

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1. Univ. of Texas Health Science Center, Houston, TX (United States)
2. FBI Academy, Quantico, VA (United States)

The authors provide experimental evidence showing that, during the restriction-enzyme digestion of DNA samples, some of the HaeIII-digested DNA fragments are small enough to prevent their reliable sizing on a Southern gel. As a result of such nondetectability of DNA fragments, individuals who show a single-band DNA profile at a VNTR locus may not necessarily be true homozygotes. In a population database, when the presence of such nondetectable alleles is ignored, they show that a pseudodependence of alleles within as well as across loci may occur. Using a known statistical method, under the hypothesis of independence of alleles within loci, they derive an efficient estimate of null allele frequency, which may be subsequently used for testing allelic independence within and across loci. The estimates of null allele frequencies, thus derived, are shown to agree with direct experimental data on the frequencies of HaeIII-null alleles. Incorporation of null alleles into the analysis of the forensic VNTR database suggests that the assumptions of allelic independence within and between loci are appropriate. In contrast, a failure to incorporate the occurrence of null alleles would provide a wrong inference regarding the independence of alleles within and between loci. 47 refs., 2 figs., 4 tabs.

• OSTI ID: 7101385
• Journal Information: American Journal of Human Genetics; (United States), Journal Name: American Journal of Human Genetics; (United States) Vol. 55:2; ISSN AJHGAG; ISSN 0002-9297
• Country of Publication: United States
• Language: English

Related Subjects

550400* -- Genetics
59 BASIC BIOLOGICAL SCIENCES
DETECTION
GENETIC MAPPING
MAPPING
MATHEMATICS
RFLPS
STATISTICS