Genetic affinities of oceanic populations based on RFLP and haplotype analysis of genetic loci on three chromosomes.

Restriction fragment length polymorphisms at the renin and factor 13B loci located at chromosome 1q32-1q42 were studied in 14 ethnic groups in the west Pacific region. The allele frequencies were combined with previously described beta-globin and albumin-vitamin D binding protein haplotype frequencies and used to assess genetic affinities among eight major ethnic-geographic groups in this region. These population groups divide into two clusters with Australian Aborigines, Island Melanesians, and Highland Melanesians forming one cluster and east Asians, Southeast Asians, Micronesians, and Polynesians forming the other. The results indicate that Micronesians and Polynesians are derived from populations in Southeast Asia and that they originated independently of the Melanesian populations.     

Ethnic variation in vitamin D-binding protein (GC): a review of isoelectric focusing studies in human populations

Summary Since the discovery in 1977 that the GC1 gene could be resolved into two common subcomponents on an isoelectric focusing (IEF) gel, a large number of ethnic groups have been screened to analyze the extent of genetic variation in human populations. Using the IEF technique, approximately 50,000 individuals from 160 different populations have been tested for the GC polymorphism. A marked variation in common GC suballele frequencies in different geographic areas seems to correlate with skin pigmentation and intensity of sun light. Pigmented (black) and keratinized (yellowish) skin type populations have a relatively high frequency of the GC ^*IF allele as compared to white skin populations. By comparison non-pigmented and non-keratinized white skin populations are generally characterized by having the maximum values of the GC ^*IS allele. The anthropologic significance of the GC locus has been enhanced further by detecting additional unique GC variants which provide useful information about evolutionary links between different populations. However, the presence of some electrophoretically identical unique variants in genetically and geographically distinct populations demand further investigation of these allelic variants to shed more light on their origins.     

Genetic polymorphism of thyroxin-binding globulin (TBG) in the Pacific area.

Human plasma samples, radiolabeled with [125I]thyroxin, from the Asian, Pacific, and Australian area have been subjected to isoelectric focusing to reveal genetic variation in thyroxin-binding globulin (TBG). A genetically determined electrophoretic slow variant, TBG S, indistinguishable from the variant found in black Africans, has been observed with a frequency of 1%-10% in all Melanesian and Polynesian populations studied. The TBG S variant is present also with low frequency in Micronesians and in some Indonesian populations. However, East Asians, Indians, and Australian Aborigines were found to be monomorphic.     

Distribution of the 3' VNTR polymorphism in the human dopamine transporter gene in world populations

A polymorphism with a variable number of tandem repeats (VNTR) found in the 3' untranslated region of the human dopamine transporter gene (DAT1) was scored in unrelated individuals drawn from 10 geographically widely dispersed populations in order to assess this marker's usefulness in human population genetics. The populations that were analyzed in this study included 4 indigenous groups of Siberia, natives of North and South America, as well as Caucasian and Oceanic groups, most of which represented small-scale societies. A total of 5 DAT1 alleles were seen overall, but only in one Siberian population, the Altai-Kizhi, were all 5 present, and in the Native Americans of Colombia the locus was monomorphic. The most common allele, DAT1*10, ranged in frequency from 52% in Greeks to 100% in South Americans. The high frequency of the DAT1*10 allele (approximately 90%) among Mongoloid groups of north and east Asia distinguishes them from most Caucasian groups. The presence of the rare DAT1*7 allele in relatively high frequency (approximately 5%) among all Siberian groups suggests a close affinity with north Asian groups, especially Mongolians. The presence of the even rarer DAT1*13 allele in one Siberian population, the Altai-Kizhi, reflects this group's long historical contact with Mongolians. The results demonstrated that the DAT1 VNTR polymorphism is useful in investigating population relationships, and that rare alleles at this locus may be particularly valuable in understanding the extent of genetic affinity between neighboring groups and in situations where admixture is suspected. However, because of both the association and linkage of this VNTR locus with attention-deficit hyperactivity disorder (ADHD) in children, and its highly restricted polymorphism (usually 3 alleles) in most human groups, the possibility of selection constraints on the DAT1 gene cannot be ignored.     

Population genetics of alpha-1-antitrypsin polymorphism in US whites, US blacks and African blacks.

An isoelectric focusing (IEF) procedure in an ultra-narrow pH range, 4.2-4.9, has been utilized to detect alpha 1-antitrypsin or alpha 1-protease inhibitor (PI) allele products in 2 US white and 3 US black populations as well as 1 native African black population. In addition to the 3 common alleles PI*M1, PI*M2 and PI*M3, products of the 4th allele PI*M4 have been identified in US whites at low-level frequency. The presence of the PI*S, PI*Z and PI*I alleles has also been verified in our population samples. While the PI*S allele is present at a polymorphic level in US whites, it is only present sporadically in US blacks and is completely absent in African blacks. The PI*Z allele was not detected in the black populations tested. The PI allele frequency data have been used to calculate white admixture in US blacks.     

Genetic studies of human apolipoproteins. XVIII. Apolipoprotein polymorphisms in Australian Aborigines

A tribal aboriginal community, the Mowanjum, from the Kimberley region in Western Australia has been screened to determine the extent of genetic variation in the products of genes coding for apolipoproteins, which are intimately involved in lipid metabolism. Of the seven systems tested, APOE and APOH revealed common structural variations, but their distribution patterns are significantly different from those found in European populations. Australian Aborigines were found to be unique because they have no APOE*2 and APOH*3 alleles and have strikingly high frequencies of the APOE*4 (26%) and APOH*1 (13%) alleles. The contrast in variation observed at these apolipoprotein loci between Australian Aborigines and Europeans not only makes these loci useful genetic markers in biologic anthropology studies but also provides a unique opportunity to investigate the role of genetic-environment interaction in determining interpopulation differences in cardiovascular disease risk factors.     

An extended survey of the genetic polymorphism at the human coagulation factor XIII: a subunit structural locus

The distribution of the three previously reported alleles, with normal products at the factor XIII A subunit structural locus, FXIIIA*1, FXIIIA*2 and FXIIIA*4 has been studied in populations from the region extending from the Indonesian archipelago through Papua New Guinea, Australia and New Zealand to the Pacific Islands of Micronesia, Melanesia and Polynesia. In addition a population from the Caspian Littoral of Iran and a population of South American Indians were studied. The FXIIIA*1 and FXIIIA*2 alleles were polymorphic in all populations studied. The distribution of the FXIIIA*4 allele suggests that it may be a Melanesian marker.     

Allele and genotype frequencies of metabolic genes in Native Americans from Argentina and Paraguay

Interethnic differences in the allele frequencies of CYP2D6, NAT2, GSTM1 and GSTT1 deletions have been documented for Caucasians, Asians, and Africans population. On the other hand, data on Amerindians are scanty and limited to a few populations from southern areas of South America. In this report we analyze the frequencies of 11 allele variants of CYP2D6 and 4 allele variants of NAT2 genes, and the frequency of GSTM1 and GSTT1 homozygous deleted genotypes in a sample of 90 donors representing 8 Native American populations from Argentina and Paraguay, identified as Amerindians on the basis of their geographic location, genealogical data, mitochondrial- and Y-chromosome DNA markers. For CYP2D6, 88.6% of the total allele frequency corresponded to *1, *2, *4 and *10 variants. Average frequencies for NAT2 *4, *5, *6 and *7 alleles were 51.2%, 25%, 6.1%, and 20.1%, respectively. GSTM1 deletion ranged from 20% to 66%, while GSTT1 deletion was present in four populations in less than 50%. We assume that CYP2D6 *2, *4, *10, *14; NAT2 *5, *7 alleles and GSTM1 and GSTT1 *0/*0 genotypes are founder variants brought to America by the first Asian settlers.     

Molecular evaluation of an Alu repeat including a polymorphic variable poly(dA) (AluVpA) in the vitamin D binding protein (DBP) gene

We investigated an Alu element at the end of intron 8 of the human vitamin D-binding protein (hDBP, group-specific component, GC) gene that shows a polymorphic poly(A) tail due to a variable number of tandem repeats (AluVpA) forming the 3 end of this member of the most abundant class of short interspersed repeated DNA element (SINES). The Alu element sequence in intron 8 of the GC gene was identical in all three common GC alleles (GC*1F, GC*1S, and GC*2) and could be classified as an Alu-Sa or Alu class-II sequence. The polymerase chain reaction was used to amplify selectively a fragment of about 200 bp containing the identified (TAAA)n repeat from genomic DNA of 188 unrelated human subjects. The size of the amplified products was determined by polyacrylamide gel electrophoresis. Four alleles (named GC-18*6, GC-I8*8, GC-I8*10, and GC-18*11) were found that differed in size by multiples of four nucleotides. The allele frequencies ranged from 0.0053 to 0.8511 and the observed heterozygosity was 26%. The stable inheritance of this polymorphic patterned poly(A) sequence was confirmed by a segregation study of a highly informative family with 19 members. Statistically significant linkage disequilibrium between the AluVpA and the GC isoelectric focusing (IEF) phenotypes was found in a sample of 188 unrelated individuals and delta values were calculated from the observed haplotype distribution.     

Geographical variation of allele frequencies at the LDH-A* locus in the arctic grayling Thymallus arcticus Pall. and in the European grayling Thymallus arcticus L

The allele frequencies of LDH-A* locus were studied in the population of Siberian grayling from the Kozhym River (Pechora basin) and in the population of European grayling from Pechora, Mezen', and Vym' rivers (Northern Dvina basin). In samples of both species (n = 134), three LDH-A phenotypes have been identified in total, which proved to be under the control of two alleles: LDH-A*100 and LDH-A*50. The alternative alleles of LDH-A* locus were identified in the populations of Siberian grayling from Kozhym River and in the population of European grayling from the same river and other Pechora tributaries, namely, LDH-A*100 and LDH-A*50 in the Siberian and the European grayling, respectively. However, in the European grayling populations from the Mezen' and Vym' rivers, both alleles occur at the frequencies of the rare LDH-A*100 allele of 0.143 and 0.222, respectively. According to the published data, the frequency of LDH-A*100 allele increases in the European grayling populations of northwestern (Finland) and southern (France) rivers, reaching 0.872 and 1.000 in Rhone and Loire, respectively, i.e., the values characteristic of the Siberian grayling populations.     

Geographic differences in the allele frequencies of the human Y-linked tetranucleotide polymorphism DYS19

We have studied the allele frequency distribution of the microsatellite locus DYS 19 in several populations with different geographical origins worldwide. Three new alleles were found. In addition, remarkable geographic and ethnic differences were observed in the allele frequency profiles and DNA marker (gene) diversity among populations and major ethnic groups. Amerindians showed an overwhelming predominance of the A allele, while in Caucasians the B allele was modal, and in Greater Asians and Africans allele C became predominant. Even within these geographic regions there were significant gradients, as exemplified by the decreasing frequency profile of the B allele from Great Britain over Germany to Slovakia. Thus, DYS 19 emerges as a useful tool for studying the structure and dynamics of human populations.     

CYP2A6 polymorphism reveals differences in Japan and the existence of a specific variant in Ovambo and Turk populations

CYP2A6 is a polymorphic enzyme, and CYP2A6 genotype has been shown to be associated with smoking habits and lung cancer. We investigated CYP2A6 polymorphism in Japanese from four different geographic areas of Japan and in the Ovambo and Turk populations. Using two polymerase chain reaction restriction fragment length polymorphisms (PCR-RFLPs), we identified the functionally important variants of CYP2A6: *1A, *1B, *1F, *1G, *4A, and *4D. In the Japanese population the highest frequencies of the CYP2A6*1A allele were observed in subjects from the Fukuoka (Kyushu Island) and Ehime (Shikoku Island) prefectures, whereas subjects in Shimane and Tottori (both located on the Japan Sea side of Honshu Island) showed the highest frequencies of the CYP2A6*1B allele. In the Tottori and Shimane groups no subject was homozygous for the CYP2A6*4A allele, a whole gene deletion type that is prevalent among Asians. In the Ovambo and Turk populations the CYP2A6*1A allele was predominant. Furthermore, two alleles undetected in the Japanese were observed in these latter two ethnic groups: CYP2A6*1G was found solely in the Ovambos, and CYP2A6*1F was found solely in the Turks. The present study is the first to show interprefecture differences in CYP2A6 polymorphism in Japanese who live in relatively close but distinct geographic areas; this is also the first study to evaluate CYP2A6 variations among these Japanese and the Ovambo and Turk populations. The distribution results of these alleles could help to define the true significance of CYP2A6 polymorphism as a genetic susceptibility marker in worldwide populations.     

Study of five haemogenetic markers (Gc, C3, Bf, Ag, and GALT) in six Indonesian populations and in 12 subgroups of Balinese

In various ethnic groups of the Indonesian archipelago and of Bali, the polymorphisms of the serum proteins Gc globulin (vitamin D-binding protein), C3 (complement component 3), Bf (complement factor B), Ag x,y (lipoprotein allotypes), and of the red cell enzyme system GALT (galactose-1P-uridyltransferase) were analysed. Among the studied proteins, the Gc system was the most informative one for the anthropologist. Besides considerable differences of frequencies of the common alleles Gc*1F, Gc*1S and Gc*2, a number of rare alleles (1A1, 1A3, 1A8, 1A9, 1A12, 1C2, 1C21, 1C24, and 2C8) and some new ones (1C28, 1C29, 1C30, 2C9) were observed. The presence of Gc*1A1 demonstrates the relationship to the Australo-Melanesian populations, but Mongolian variants (1A3, 1A8, 1A9, 1C2) were also encountered. Within the C3 system a very high frequency of the C3*S allele was observed in all populations. The rare alleles C3*F0.55, C3S1, and C3*S0.5 were observed in some groups. A new allele (C3*F0.35) was detected in a Chinese individual and in a nobleman from Bali. The frequency of the Bf*F allele was rather low in general, and the Bf*S0.7 allele was found in three Indonesian individuals only. The Ag*(x) frequencies were rather high, as it is known for Asiatic populations. Variability among subgroups was not very pronounced. The GALT*2 allele (Duarte variant of the enzyme) was observed very rarely; however, it was present in several populations. Enzyme activities could not be determined, and therefore we cannot tell whether the galactosaemia gene (GALT*0) was present or not.     

HLA-DRB1 Alleles Are Associated with the Susceptibility to Sporadic Parkinson’s Disease in Chinese Han Population

Immune disorders may play an important role in the pathogenesis of Parkinson''s disease (PD). Recently, polymorphisms in the HLA-DR region have been found to be associated with sporadic PD in European ancestry populations. However, polymorphisms in the HLA complex are highly variable with ethnic and geographic origin. To explore the relationships between polymorphisms of the HLA-DR region and sporadic PD in Chinese Han population, we genotyped 567 sporadic PD patients and 746 healthy controls in two independent series for the HLA-DRB1 locus with Polymerase chain reaction-sequence based typing(PCR-SBT). The χ² test was used to evaluate the distribution of allele frequencies between the patients and healthy controls. The impact of HLA-DRB1 alleles on PD risk was estimated by unconditional logistic regression. We found a significant higher frequency of HLA-DRB1*0301 in sporadic PD patients than in healthy controls and a positive association, which was independent of onset age, between HLA-DRB1*0301 and PD risk. Conversely, a lower frequency of HLA-DRB1*0406 was found in sporadic PD patients than in healthy controls, with a negative association between HLA-DRB1*0406 and PD risk. Furthermore, a meta-analysis involving 195205 individuals was conducted to summarize the frequencies of these two alleles in populations from various ethnic regions, we found a higher frequency of HLA-DRB1*0301, but a lower frequency of HLA-DRB1*0406 in European ancestry populations than that in Asians, this was consistent with the higher prevalence of sporadic PD in European ancestry populations. Based on these results, we speculate that HLA-DRB1 alleles are associated with the susceptibility to sporadic PD in Chinese Han population, among them HLA-DRB1*0301 is a risk allele while the effect of HLA-DRB1*0406 deserves debate.     

Genotypes of vitamin-D-binding protein (DBP) in patients with chronic obstructive pulmonary disease and healthy population of Republic Bashkortostan

The distribution of alleles and genotypes of vitamin D-binding protein (DBP) gene has been studied in patients with Chronic Obstructive Pulmonary Disease (COPD, n = 298) and healthy individuals (n = 237) from two ethnic groups (Tatars and Russians) living in Republic Bashkortostan. Statistically significant differences in the distribution of DBP gene genotypes between Tatars and Russians (chi2 = 8.854, df = 5, P = 0.04) were revealed. The pattern of allele's distribution within DBP gene was similar in healthy control subjects of both ethnic groups, with gradient reduction in row GC*1S> GC*1F> GC*2. The most common genotypes were: GC*1F/1S in Tatars (36.79%) and GC*1S/2 in Russians (34.62%). It has been shown, that Tatars with genotype GC*1F/1S have a lower risk of COPD development: the frequency of GC*1F/1S genotype in COPD patients was significantly lower than in healthy individuals (19.85% versus 36.79%; chi2 = 7.622, P = 0.0067, Pcor = 0.0335; OR = 0.42 CI 95% 0.22-0.79). At the same time, COPD patients from the same group had higher frequency of GC* 1F/2 genotype than healthy individuals (19.08% versus 8.49%; chi2 = 4.52, P = 0.033, Pcor = 0.165; OR = 2.54 CI 95% 1.067-6.20). In Russian population the distribution of alleles and genotypes of DBP gene were similar in COPD patients and healthy individuals.     

To the research of the gene pool of the Gagauz population of Moldavia

Population genetic data on Gagauzes from Moldavia are reported here for the first time. AB0 and Rhesus blood groups, serum protein group (HP, TF, GC) and the red cell enzyme polymorphism PGM1 were determined in 190 Gagauzes. In addition to this the ability to taste PTC was tested. The following allele frequencies were found: AB0*0 = 0.5241, AB0*A = 0.3279, AB0*B = 0.1480; RH*D = 0.6083, RH*d = 0.3917; HP*1 = 0.3544, HP*2 = 0.6456; TF*C1 = 0.7472, TF*C2 = 0.1770, TF*C3 = 0.0730, TF*B = 0.0028; GC*1F = 0.1025, GC*1S = 0.5932, GC*2 = 0.3043; PGM*1+ = 0.5932; PGM*1- = 0.1000, PGM*2+ = 0.2607, PGM*2- = 0.1107. The frequency of the PTC*T allele was found to be 0.5298. These frequencies and genetic distance analyses show that the gene pool of the Gagauzes is similar to that of neighbouring southeastern European populations.     

Molecular analysis of the gene for the human vitamin-D-binding protein (group-specific component): allelic differences of the common genetic GC types

Summary DNA sequence analysis of the polymerase chain reaction products, including the coding region for amino acids 416 and 420, of the vitamin-D-binding protein (DBP, group-specific component, GC) shows allelespecific differences. The GC2 and GC1F phenotypes have an aspartic acid residue at amino acid position 416, whereas the GC1S phenotype has a glutamic acid at this position. In the GC2 phenotype, amino acid 420 is a lysine residue, and in the both common GC1 phenotypes, it is a threonine residue. The nucleotide exchanges involve a HaeIII (position 416) and a StyI (position 420) restriction site: the HaeIII restriction site is specific for the GC^*1S allele and the StyI restriction site is specific for the GC^*2 allele. We have tested 140 individual genomic DNA samples for the HaeIII site and 148 samples for the StyI site by restriction fragment length polymorphism (RFLP) analysis with a DBP-specific direct genomic DNA probe, and have compared these findings with the GC phenotype classification, by isoelectric focusing (IEF) of the corresponding plasma. The results of the HaeIII RFLP analysis and the IEF typing were in complete agreement. By using our DNA probe, we could disclose, in addition to the StyI site at amino acid position 420, two further StyI site downstream: one was specific for the GC^*1S allele and another for the GC^*1F allele. In 147 samples, there was agreement between the IEF GC typing and the analysis of the StyI restriction sites. In a single case, the observed result of the StyI-digest differed from the result expected after IEF classification: homozygous GC 1F-1F by IEF and heterozygous by StyI RFLP analysis. We discuss this finding as a recombination event or a possible silent allele in IEF typing. The GC polymorphism revealed by Southern blot analysis of StyI-digests provides an informative DNA marker system for chromosome 4q11–q13.     

Cytochrome P4501A1 polymorphisms in the Amerindian and Mestizo populations of Mexico

Several polymorphisms in the CYP1A1 locus have been identified and their genotypes appear to exhibit population frequencies that depend on ethnicity. We studied two CYP1A1 polymorphic sites (position 4889 and 6235) in a group of 212 unrelated healthy individuals belonging to three different Mexican populations (106 Mexican Mestizos, 52 Teenek and 54 Mayos). Comparison among Mexican populations showed increased frequency of the *Ile allele (A on position 4889) in Mexican Mestizos when compared to Amerindians (p < 0.05). The analysis of position 6235 showed increased frequencies of *m2 (C in this position) allele in Teenek when compared to Mestizos and Mayos (p < 0.05) and of *m2/*m2 genotype when compared to Mestizos (p < 0.05). Amerindian populations (from Mexico and South America) presented the lowest frequencies of *Ile (position 4889) and *m1 (position 6235) alleles, however these frequencies vary according to the ethnic group studied. Mexican Amerindian groups together with other South Amerindian populations showed the highest frequencies for *Val at position 4889 and the *m2 allele at position 6235. The present study corroborates the high frequencies of*Val and *m2 alleles in the Amerindian populations and detects some differences between Mexican populations that correlate with linguistic differences. Our data could be helpful in understanding the distribution of these polymorphisms and in clarifying their roles as genetic and evolution markers in Amerindian populations.     

PCR/oligonucleotide probe typing of HLA class II alleles in a Filipino population reveals an unusual distribution of HLA haplotypes.

We have analyzed the distribution of HLA class II alleles and haplotypes in a Filipino population by PCR amplification of the DRB1, DQB1, and DPB1 second-exon sequences from buccal swabs obtained from 124 family members and 53 unrelated individuals. The amplified DNA was typed by using nonradioactive sequence-specific oligonucleotide probes. Twenty-two different DRB1 alleles, including the novel Filipino *1105, and 46 different DRB1/DQB1 haplotypes, including the unusual DRB1*0405-DQB1*0503, were identified. An unusually high frequency (f = .383) of DPB1*0101, a rare allele in other Asian populations, was also observed. In addition, an unusual distribution of DRB1 alleles and haplotypes was seen in this population, with DR2 (f = .415) and DRB1*1502-DQB1*0502 (f = .233) present at high frequencies. This distribution of DRB1 alleles differs from the typical HLA population distribution, in which the allele frequencies are more evenly balanced. The distribution of HLA class II alleles and haplotypes in this Filipino population is different from that of other Asian and Pacific groups: of those populations studied to date; the Indonesian population is the most similar. DRB1*1502-DQB1*0502 was in strong linkage disequilibrium (D'' = .41) with DPB1*0101 (f = .126, for the extended haplotype), which is consistent with selection for this DR, DQ, DP haplotype being responsible for the high frequency of these three class II alleles in this population.     

Y-chromosome-specific microsatellite variation in Australian aboriginals

The frequency distributions of 4 highly polymorphic Y-chromosome-specific microsatellites (DYS19, DYS390, DYS391, and DYS392) were determined in 79 unrelated Australian Aboriginal males from the Northern Territory. These results are compared with those observed in worldwide populations at both the locus and the haplotype level. Common alleles in Aboriginals are DYS19*15 (49%), DYS19*14 (28%), DYS390*19 (39%), DYS390*24 (20%), DYS391*10 (72%), DYS392*11 (63%), and DYS392*13 (28%). No evidence of reduced gene diversity was observed for these Y-chromosome alleles. DYS390 exhibits the most complex arrangement, displaying a bimodal distribution composed of common alleles (*22-*26), and rare short alleles (*18-*20), with an intermediate allele (*21) being absent. DYS390*20, previously reported only in Papuans and Samoans, is observed for the first time in Aboriginals. Compared with a recent study of Aboriginals, our sample exhibits considerable diversity in the haplotypes associated with the rare DYS390*19 allele, indicating that this allele is of considerable antiquity, if it arose as a single deletion event. Combining all 4 Y-chromosome-linked microsatellites produced 41 unique haplotypes, which were linked using a median-joining network. This network shows that most (78%) of our Aboriginal haplotypes fall into 2 distinct clusters, which likely represent 2 separate lineages. Seven haplotypes are shared with haplotypes found in a recent study of Aboriginals, and 7 are shared with a Spanish population. The cluster of Aboriginal haplotypes associated with the short DYS390 alleles does not share any haplotypes with the Spanish, indicating that this cluster of haplotypes is unique to Australian Aboriginals. Limited data from 4 worldwide populations used to construct haplotypes based on 3 loci (DYS19, DYS390, DYS392) show that only 4 of these haplotypes are seen in Australian Aboriginals. Shared haplotypes may be the result of admixture and/or recurrent mutation at these loci. Expanding the haplotype analysis to include biallelic markers on the Y chromosome will resolve this issue.