Forensic evaluation of the AmpFℓSTR Identifiler kit in nine Mexican native populations from the pre-Columbian Mesoamerican region.

Allele frequency distribution and forensic parameters of the AmpFℓSTR Identifiler kit was determined in nine Mexican Amerindian populations based on 1,040 unrelated individuals from the pre-Columbian region known as Mesoamerica. Hardy-Weinberg equilibrium was demonstrated for most of the short tandem repeats (STRs) in all nine populations. The power of discrimination and exclusion were higher than 0.99999 and 0.997942, respectively. In addition, a brief overview of the genetic relatedness and structure (F st = 2.62 %; p = 0.00000) between these populations is presented.

Population structure and paternal admixture landscape on present-day Mexican-Mestizos revealed by Y-STR haplotypes.

Mestizos currently represent most of the Mexican population (>90%); they are defined as individuals born in the country having a Spanish-derived last name, with family antecedents of Mexican ancestors back at least to the third generation. Mestizos are result of 500 years of admixture mainly among Spaniards, Amerindians, and African slaves. Consequently, a complex genetic pattern has been generated throughout the country that has been scarcely studied from the paternal point of view. This fact is important, taking into account that gene flow toward the New World comprised largely males. We analyzed the population structure and paternal admixture of present-day Mexican-Mestizo populations based on Y-STRs. We genotyped at least 12 Y-STRs in DNA samples of 986 males from five states: Aguascalientes (n = 293); Jalisco (n = 185); Guanajuato (n = 168); Chiapas (n = 170); and Yucatán (n = 170). AmpFlSTR Y-filer and Powerplex-Y(R) kits were used. Inclusion of North and Central Y-STR databases in the analyses allowed obtaining a Y-STR variability landscape from Mexico. Results confirmed the population differentiation gradient previously noted in Mestizos with SNPs and autosomal STRs throughout the Mexican territory: European ancestry increments to the Northwest and, correspondingly, Amerindian ancestry increments to the Center and Southeast. In addition, SAMOVA test and Autocorrelation Index for DNA Analysis autocorrelogram plot suggested preferential gene flow of males with neighboring populations in agreement with the isolation-by-distance model. Results are important for disease-risk studies (principally male-related) and for human identification purposes, because Y-STR databases are not available on the majority of Mexican-Mestizo populations.

Origin and genetic differentiation of three Native Mexican groups (Purépechas, Triquis and Mayas): contribution of CODIS-STRs to the history of human populations of Mesoamerica.

BACKGROUND: CODIS-STRs in Native Mexican groups have rarely been analysed for human identification and anthropological purposes. AIM: To analyse the genetic relationships and population structure among three Native Mexican groups from Mesoamerica. SUBJECTS AND METHODS: 531 unrelated Native individuals from Mexico were PCR-typed for 15 and 9 autosomal STRs (Identifiler™ and Profiler™ kits, respectively), including five population samples: Purépechas (Mountain, Valley and Lake), Triquis and Yucatec Mayas. Previously published STR data were included in the analyses. RESULTS: Allele frequencies and statistical parameters of forensic importance were estimated by population. The majority of Native groups were not differentiated pairwise, excepting Triquis and Purépechas, which was attributable to their relative geographic and cultural isolation. Although Mayas, Triquis and Purépechas-Mountain presented the highest number of private alleles, suggesting recurrent gene flow, the elevated differentiation of Triquis indicates a different origin of this gene flow. Interestingly, Huastecos and Mayas were not differentiated, which is in agreement with the archaeological hypothesis that Huastecos represent an ancestral Maya group. Interpopulation variability was greater in Natives than in Mestizos, both significant. CONCLUSION: Although results suggest that European admixture has increased the similarity between Native Mexican groups, the differentiation and inconsistent clustering by language or geography stresses the importance of serial founder effect and/or genetic drift in showing their present genetic relationships.

Y-linked haplotypes in Amerindian chromosomes from Mexican populations: genetic evidence to the dual origin of the Huichol tribe.

We studied six Y-linked short tandem repeats (Y-STRs) to describe the internal diversity of the Amerindian haplogroup Q-M3 in 129 males from eight Mexican populations. The low gene diversity in the Huichol tribe demonstrated the effects of genetic drift, attributable to geographic isolation and founder effect. The presence of two principal paternal lineages supported the historical and anthropometric records, which indicate that Huichols were formed by the fusion of two ancestral Mexican tribes. Moreover, genetic distances and close relationships of haplotypes between Huichols and Tarahumaras were in agreement with their linguistic affiliation. The high genetic diversity of the Purépechas and wide distribution of haplotypes along the constructed network-joining tree suggest that the present genetic composition was influenced by Purépecha dominance in western Mesoamerica. The Y-haplotypes shared between populations suggest that, among the Amerindian tribes studied herein, the paternal genetic pool of Nahuas could have contributed more importantly to the European-admixed population, the Mexican-Mestizos.

Autosomal dominant inheritance in Cantú syndrome (congenital hypertrichosis, osteochondrodysplasia, and cardiomegaly).

Cantú syndrome (CS) is characterized by congenital hypertrichosis, osteochondrodysplasia, cardiomegaly, and coarse facial appearance; autosomal recessive inheritance has been postulated. We report on a Mexican family with CS; the affected members are the 44-year-old father and his two children (a male and female), aged 14 and 4 years, respectively; each shows the classic characteristics, but the father and the brother also have a previously unreported feature, namely, a thick calvarium. This is the first reported instance of male-to-male transmission of CS. With the paternal age effect found in the reported sporadic cases and the segregation analysis [Robertson et al., 1999], autosomal dominant inheritance is more likely than autosomal recessive inheritance. The cases of affected sibs reported by Cantú et al. [1982] could be explained by parental gonadal mosaicism.

Further clinical delineation in trisomy 1q32 syndrome.

A male newborn with multiple congenital abnormalities was studied. Clinically, he showed prominent forehead, facial dysmorphism, ear malformations, congenital heart defect and limb anomalies. The cytogenetic studies demonstrated a karyotype 46,XY, der(18) t(1;18)(q32;p11.3)pat with partial trisomy 1q32-qter and a monosomy 18p. The patient displayed clinical features of trisomy 1q but not of monosomy 18p. There are around 80 reports of trisomy 1q32. The purpose of this paper is to describe the first case of a translocation involving 1q and 18p chromosome breakpoints. Additional findings detected in the propositus permit us a further delineation of the trisomy 1q syndrome.

An intracranial carcinoma in a Mexican woman with Bloom syndrome.

An intracranial cell squamous carcinoma was found in a 27-year-old Mexican woman with Bloom syndrome (BS), including growth retardation, sun-sensitive telangiectatic erythema, defective immunity, and increased number of mitotic chiasmata and sister chromatid exchanges. The tumour, probably originating from the inner or middle ear epithelium, was resected but the patient died a few days after surgery. There was no parental consanguinity nor Jewish or European ancestry for at least five generations; in fact, her parents were mostly indigenous people. This case represents an undescribed intracranial malignancy in BS and the third Mexican BS patient reported. The typical BS phenotype in a woman with pigmented skin challenges the contention that pigmented females are less severely affected.

Familial iridogoniodysgenesis and skeletal anomalies: a probable new autosomal recessive disorder.

Three sibs with congenital glaucoma, skeletal anomalies, and peculiar facial appearance were studied. At birth, enlarged eyes and corneae were present in the proposita and her two brothers due to congenital glaucoma secondary to iridogoniodysgenesis (IGD). The purpose of this article is to describe the second familial case with IGD and skeletal anomalies as the family previously described by García-Cruz et al. in 1990, corroborating this new distinct dysmorphic syndrome with probable autosomal recessive inheritance.