Forensic Science International: Genetics
Volume 6, Issue 1 , Pages e3-e4, January 2012

Allele frequencies of fifteen STR loci in U.S. immigrants from Haiti compared with African Americans and Afro-Caribbeans

BRT Laboratories, 400 West Franklin Street, Baltimore, MD 21201, United States

Baltimore Police Department, 601 E. Fayette St., Baltimore, MD 21201, United States

Received 15 February 2010 published online 06 December 2010.

Article Outline

 

Dear Editor,

About 20,000 Haitians emigrate to the United States each year. Many are beneficiaries of family-based petitions from naturalized U.S. citizens [1]. Since Haitian birth and marriage records are often nonexistent, adjudicators of the U.S. Citizenship and Immigration Service have evaluated claimed relationships in light of genetic tests for many years [2]. Tests are provided by non-governmental laboratories accredited by the AABB and meeting College of American Pathologists proficiency test requirements. The population derives from the European colonization of the Americas and the slave trade that flourished between the 15th and 19th centuries. The present derivative black populations of the Western hemisphere are admixtures of primarily West Africans and Europeans with small contributions from Amerindians and other groups. We report Haitian allele frequencies of 15 widely-used short tandem repeat (STR) loci (D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D21S11, CSF1PO, FGA, PentaD, PentaE, TH01, TPOX and vWA) and compare these frequencies with those of African Americans (AAs) [3], [4] and with four Afro-Caribbean populations from Trinidad, Jamaica and the Bahamas [5] as well as from the adjacent Dominican Republic [6].

DNA for microsatellite analysis was obtained from 795 Haitian immigration petitioner's samples (random samples used in casework) of blood that were dried on FTA® paper (Whatman, Clifton NJ). Each person included in the study signed a release, consenting to have his or her DNA tested and to have anonymous results used for laboratory studies of relationships and populations. Ethical requirements for use of genotyping data were followed throughout. The authors understand and accept the requirements for this type of paper [7]. In order to exclude relatives from the sample, only one person per case, the petitioner, was included in the sample and a government-issued visa assured the origin and identity of each petitioner. All specimens were collected in the U.S. Records were searched for people with identical surnames or ones who appeared in more than one case to prevent subject duplication. Blood samples were labeled, chain-of-custody was assured, and laboratory processing and analysis meet current AABB Standards [8].

PCR was performed using a 1.2mm punch from FTA paper samples and widely used commercial reagents (Promega PowerPlex® 16) [9]. Alleles of the STR loci were identified using capillary electrophoresis (Applied Biosystems® 3130 and 3100 Avant) and designated in accordance with the recommendations of the DNA commission of the International Society for Forensic Genetics (ISFG) [10], [11]. Allelic ladders were supplied by the manufacturer and included common complete and partial alleles.

After formatting [12], [13], the data were analyzed with validated software [14] for Hardy–Weinberg disequilibrium, using 105 steps in the Markov chain and 103 dememorization steps. Data were also evaluated for linkage disequilibrium, using 104 permutations, 10 initial conditions and a significance level of 0.05. Tests for linkage disequilibrium (LD) were initially performed on a subset of 430 Haitians, producing three p-values below 0.05. This is consistent with expectations that an average of 5% of tests (5.25/105 pair-wise tests) will appear linked. The loci in each pair are on different chromosomes: CSF1PO-D13S317, D13S317-D8S1179, D13S317-FGA. Additional tests, for LD on smaller subsets of the first group and on a second group of 365 Haitians, produced a different linkage profile. Findings indicated that the statistical results suggesting linkage were chance events in a large database [15].

Haitian allele frequencies, locus heterozygosities (H), 2-parent average probabilities of exclusion [16] (PE), powers of discrimination [17] (PD), and probabilities of linkage equilibrium (P) are summarized in Table 1.

Two-sample χ2 analyses were used to determine significant differences between Haitian allele frequencies per locus and each of the other five populations [18]. The null hypotheses were that samples from the two compared nations were drawn from the same population. Allele counts were scaled to adjust for unequal sample sizes and combined into bins in order to provide a minimum of 5 observations per bin in each population [18]. Comparisons of allele frequencies per locus of the 6 populations are summarized in Table 2. One to five of 15 loci showed small but significant differences between Haitian and the various populations other than Dominicans. Haitians showed significant differences in allele frequencies from Dominicans at all 15 loci. Dominicans also appear less like other African Americans and Afro-Caribbeans than other groups. Small differences in allele frequencies are expected at a few tested loci between these similar populations, but the statistically significant differences between Dominicans and Haitians at all loci are unexpected. These results could be related to sampling errors or measurement differences, but they are likely small and real allele frequency variations (Figure 1).

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Appendix A. Supplementary data 

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References 

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PII: S1872-4973(10)00184-5

doi:10.1016/j.fsigen.2010.11.001

Forensic Science International: Genetics
Volume 6, Issue 1 , Pages e3-e4, January 2012

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