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In 2000, Canada established a CODIS-based National DNA Databank (NDDB) composed of two indices: a Convicted Offender Index (COI) and a Crime Scene Index (CSI). Our laboratory populates the CSI index with single-source and mixed profiles on the 13 P+/COfiler ® loci. These mixtures are coded based on the number of mixed loci (loci with more than 2 alleles). We first compared the behaviour of several hundreds low complexity mixtures (≤3 mixed loci), moderate complexity mixtures (4–6 mixed loci) and single-source profiles uploaded over the past 9 years, when run against 180000 COI profiles. We demonstrated the value of searching a databank with mixtures as hundreds of matches were reported to investigators, while the proportion of rejected matches was similar across the 3 types of samples. Based on these results, we designed a new study to evaluate 130 complex (7–13 mixed loci), two-contributor mixtures which were run against the COI. Results show that such mixtures return a manageable number of candidate matches in spite of their complexity: 70% returned no candidates while only a few generated more than one candidate. Databanking strategies coupled with mixture interpretation guidelines and review of original electropherograms maximise the use of a databank while minimising the risk of adventitious hits.

The aim of this study was to identify mutations in the lipoprotein lipase (LPL) gene in 20 unrelated patients with familial lipoprotein deficiency (FLLD) and to investigate the genotype/phenotype relationship. The previously reported G188E mutation (Monsalve et al., J Clin Invest 86:728-734, 1990) was screened for and found to be present in seven individuals (12/40 alleles). In addition, three patients were heterozygous for the 2.0 kb insertion (Langlois et al., Proc Nalt Acad Sci US 86:948-952, 1989). Two approaches were taken for new mutation detection; single-strand conformation polymorphism and sequencing to identify micro-mutations in the proximal promoter and exons 1-9 of the LPL gene and Southern blotting to identify gross mutations. Ten different point mutations were found (W86G, A158T, H183Q, G188E, S193R, P207L, L252X, N291S, M301T, L303P). Additionally, a two nucleotide deletion in exon 6 (delta1006-1007), a six nucleotide deletion in exon 8 (delta1441-1447), and a silent substitution in the wobble position of codon E118 were identified. In vitro mutagenesis and expression in COS-B cells suggested that the A158T and S193R substitutions virtually abolished enzyme activity. In analysing the genotype/phenotype relationship, there was no strong association between age at diagnosis, severity of symptoms, lipid levels, and the nature/position of the mutation. Triglyceride levels, however, were higher in compound heterozygotes compared to true homozygotes, possibly reflecting increased instability of heterodimers. Overall, 29 of 40 (72.5%) mutant alleles were identified. Failure to identify the mutation in 11 alleles might reflect the inadequacy of the method or the possibility that mutations lie within regions of the gene not screened in the study because of lack of availability of sequence.

Abstract Subjects with combined hyperlipidemia (CHL) were screened for mutations in the lipoprotein lipase (LPL) gene by single-strand conformational polymorphism, and a previously reported G→A DNA sequence change in exon 2, causing substitution of Asp by Asn at position 9, was identified in 2 individuals. Because this substitution destroys a recognition site for Taq I, pooling of DNA samples, amplification, and digest with Taq I allowed the rapid screening of 1563 healthy individuals and patients of Dutch, Swedish, English, and Scottish origin. In the general populations of all four countries, healthy carriers of the mutation were detected at a frequency of 1.6% to 4.4% (mean, 3.0%; 95% confidence interval, 2.0% to 4.0%). The frequency of carriers was roughly twice as high (range, 4.0% to 9.8%) in selected patients with CHL or type IV hyperlipoproteinemia or in subjects with angiographically assessed atherosclerosis; the frequency was consistently higher in each patient group compared with its matched control group. In 773 healthy men from two general practices in the United Kingdom, 25 carriers and 2 homozygotes for the mutation were identified. In these 27, plasma triglyceride but not plasma cholesterol levels were significantly higher than in noncarriers (2.25 versus 1.82 mmol/L, P