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Juan J Sanchez

Publications and source records attributed to Juan J Sanchez.

12 recordsLinked to original sources
PubMed2007

Carrier frequency of a nonsense mutation in the adenosine deaminase (ADA) gene implies a high incidence of ADA-deficient severe combined immunodeficiency (SCID) in Somalia and a single, common haplotype indicates common ancestry.

Inherited adenosine deaminase (ADA) deficiency is a rare metabolic disorder that causes immunodeficiency, varying from severe combined immunodeficiency (SCID) in the majority of cases to a less severe form in a small minority of patients. Five patients of Somali origin from four unrelated families, with severe ADA-SCID, were registered in the Greater London area. Patients and their parents were investigated for the nonsense mutation Q3X (ADA c7C>T), two missense mutations K80R (ADA c239A>G) and R142Q (ADA c425G>A), and a TAAA repeat located at the 3' end of an Alu element (AluVpA) positioned 1.1 kb upstream of the ADA transcription start site. All patients were homozygous for the haplotype ADA-7T/ADA-239G/ADA-425G/AluVpA7. Among 207 Somali immigrants to Denmark, the frequency of ADA c7C>T and the maximum likelihood estimate of the frequency of the haplotype ADA-7T/ADA-239G/ADA-425G/AluVpA7 were both 0.012 (carrier frequency 2.4%). Based on the analysis of AluVpA alleles, the ADA c7C/T mutation was estimated to be approximately 7,100 years old. Approximately 1 out of 5 - 10000 Somali children will be born with ADA deficiency due to an ADA c7C/T mutation, although within certain clans the frequency may be significantly higher. ADA-SCID may be a frequent immunodeficiency disorder in Somalia, but will be underdiagnosed due to the prevailing socioeconomic and nutritional deprivation.

Adenosine Deaminase↗
PubMed2006

Multiplexed SNP typing of ancient DNA clarifies the origin of Andaman mtDNA haplogroups amongst South Asian tribal populations.

The issue of errors in genetic data sets is of growing concern, particularly in population genetics where whole genome mtDNA sequence data is coming under increased scrutiny. Multiplexed PCR reactions, combined with SNP typing, are currently under-exploited in this context, but have the potential to genotype whole populations rapidly and accurately, significantly reducing the amount of errors appearing in published data sets. To show the sensitivity of this technique for screening mtDNA genomic sequence data, 20 historic samples of the enigmatic Andaman Islanders and 12 modern samples from three Indian tribal populations (Chenchu, Lambadi and Lodha) were genotyped for 20 coding region sites after provisional haplogroup assignment with control region sequences. The genotype data from the historic samples significantly revise the topologies for the Andaman M31 and M32 mtDNA lineages by rectifying conflicts in published data sets. The new Indian data extend the distribution of the M31a lineage to South Asia, challenging previous interpretations of mtDNA phylogeography. This genetic connection between the ancestors of the Andamanese and South Asian tribal groups approximately 30 kya has important implications for the debate concerning migration routes and settlement patterns of humans leaving Africa during the late Pleistocene, and indicates the need for more detailed genotyping strategies. The methodology serves as a low-cost, high-throughput model for the production and authentication of data from modern or ancient DNA, and demonstrates the value of museum collections as important records of human genetic diversity.

Asian People↗
PubMed2006

A multiplex assay with 52 single nucleotide polymorphisms for human identification.

A total of 52 SNPs reported to be polymorphic in European, Asian and African populations were selected. Of these, 42 were from the distal regions of each autosome (except chromosome 19). Nearly all selected SNPs were located at least 100 kb distant from known genes and commonly used STRs. We established a highly sensitive and reproducible SNP-typing method with amplification of all 52 DNA fragments in one PCR reaction followed by detection of the SNPs with two single base extension reactions analysed using CE. The amplicons ranged from 59 to 115 bp in length. Complete SNP profiles were obtained from 500 pg DNA. The 52 loci were efficiently amplified from degraded samples where previously only partial STR profiles had been obtained. A total of 700 individuals from Denmark, Greenland, Somalia, Turkey, China, Germany, Taiwan, Thailand and Japan were typed, and the allele frequencies estimated. All 52 SNPs were polymorphic in the three major population groups. The mean match probability was at least 5.0 x 10(-19) in the populations studied. Typical paternity indices ranged from 336 000 in Asians to 549 000 in Europeans. Details of the 52 SNP loci and population data generated in this work are freely available at http://www.snpforid.org.

DNA Fingerprinting↗
PubMed2005

Introduction of an single nucleodite polymorphism-based "Major Y-chromosome haplogroup typing kit" suitable for predicting the geographical origin of male lineages.

The European Consortium "High-throughput analysis of single nucleotide polymorphisms for the forensic identification of persons--SNPforID", has performed a selection of candidate Y-chromosome single nucleotide polymorphisms (SNPs) for making inferences on the geographic origin of an unknown sample. From more than 200 SNPs compiled in the phylogenetic tree published by the Y-Chromosome Consortium, and looking at the population studies previously published, a package of 29 SNPs has been selected for the identification of major population haplogroups. A "Major Y-chromosome haplogroup typing kit" has been developed, which allows the multiplex amplification of all 29 SNPs in a single reaction. Allele genotyping was performed with a single base extension reaction (minisequencing) detected by CE. The validation of the multiplex was performed in a total of 1126 unrelated males distributed among 12 worldwide populations. The approach takes advantage of the specific geographic distribution of the Y-chromosome haplogroups and demonstrates the utility of binary polymorphisms to infer the origin of a male lineage.

Africa↗
PubMed2005

High frequencies of Y chromosome lineages characterized by E3b1, DYS19-11, DYS392-12 in Somali males.

We genotyped 45 biallelic markers and 11 STR systems on the Y chromosome in 201 male Somalis. In addition, 65 sub-Saharan Western Africans, 59 Turks and 64 Iraqis were typed for the biallelic Y chromosome markers. In Somalis, 14 Y chromosome haplogroups were identified including E3b1 (77.6%) and K2 (10.4%). The haplogroup E3b1 with the rare DYS19-11 allele (also called the E3b1 cluster gamma) was found in 75.1% of male Somalis, and 70.6% of Somali Y chromosomes were E3b1, DYS19-11, DYS392-12, DYS437-14, DYS438-11 and DYS393-13. The haplotype diversity of eight Y-STRs ('minimal haplotype') was 0.9575 compared to an average of 0.9974 and 0.9996 in European and Asian populations. In sub-Saharan Western Africans, only four haplogroups were identified. The West African clade E3a was found in 89.2% of the samples and the haplogroup E3b1 was not observed. In Turks, 12 haplogroups were found including J2*(xJ2f2) (27.1%), R1b3*(xR1b3d, R1b3f) (20.3%), E3b3 and R1a1*(xR1a1b) (both 11.9%). In Iraqis, 12 haplogroups were identified including J2*(xJ2f2) (29.7%) and J*(xJ2) (26.6%). The data suggest that the male Somali population is a branch of the East African population - closely related to the Oromos in Ethiopia and North Kenya - with predominant E3b1 cluster gamma lineages that were introduced into the Somali population 4000-5000 years ago, and that the Somali male population has approximately 15% Y chromosomes from Eurasia and approximately 5% from sub-Saharan Africa.

Chromosomes, Human, Y↗
PubMed2005

SNP typing on the NanoChip electronic microarray.

We describe a single nucleotide polymorphism (SNP) typing protocol developed for the NanoChip electronic microarray. The NanoChip array consists of 100 electrodes covered by a thin hydrogel layer containing streptavidin. An electric currency can be applied to one, several, or all electrodes at the same time according to a loading protocol generated by the user. Biotinylated deoxyribonucleic acid (DNA) is directed to the pad(s) via the electronic field(s) and bound to streptavidin in the hydrogel layer. Subsequently, fluorescently labeled reporter oligos and a stabilizer oligo are hybridized to the bound DNA. Base stacking between the short reporter and the longer stabilizer oligo stabilizes the binding of a matching reporter, whereas the binding of a reporter carrying a mismatch in the SNP position will be relatively weak. Thermal stringency is applied to the NanoChip array according to a reader protocol generated by the user and the fluorescent label on the matching reporter is detected.

Base Sequence↗
PubMed2005

Typing of Y chromosome SNPs with multiplex PCR methods.

We describe a method for the simultaneous typing of Y-chromosome single nucleotide polymorphism (SNP) markers by means of multiplex polymerase chain reaction (PCR) strategies that allow the detection of 35 Y chromosome SNPs on 25 amplicons from 100 to 200 pg of chromosomal deoxyribonucleic acid (DNA). Multiplex PCR amplification of the DNA was performed with slight modifications of standard PCR conditions. Single-base extension (SBE) was performed using the SNaPshot kit containing fluorescently labeled ddNTPs. The extended primers were detected on an ABI 3100 sequencer. The most important factors for the creation of larger SNP typing PCR multiplexes include careful selection of primers for the primary amplification and the SBE reaction, use of DNA primers with homogenous composition, and balancing the primer concentrations for both the amplification and the SBE reactions.

Base Sequence↗
PubMed2004

Duplications of the Y-chromosome specific loci P25 and 92R7 and forensic implications.

In the present study, we demonstrate that two commonly used Y-chromosome single nucleotide polymorphisms (SNPs), P25 and 92R7, are paralogous sequence variants (PSVs) originating from segmental duplications and that at least one of the sequence variants in each group of loci is polymorphic. Several methodologies were used in order to detect the SNP alleles and the PSVs of the loci. All results obtained with the various typing techniques supported the conclusion. The allele distributions of the binary markers were analysed in more than 600 males with seven different haplogroups. For P25, the ancestral allele C was found in several samples from different haplogroups. The derived allele A was always present with an additional C variant. Haplogroup P was defined by the derived allele A at the 92R7 locus. However, the ancestral allele G was always associated with an A variant due to the duplication.

Chromosomes, Human, Y↗
PubMed2004

Multiplex PCR, amplicon size and hybridization efficiency on the NanoChip electronic microarray.

We tested the SNP typing protocol developed for the NanoChip electronic microarray by analyzing the four Y chromosome loci SRY1532, SRY8299, TAT, and 92R7. Amplicons of different lengths containing the same locus were purified and addressed to the NanoChip array and fluorescently labelled reporter probes were hybridized to the amplicons. We demonstrated that as little as 10-30 fmol of 50 bp DNA amplicons was sufficient to obtain strong and reproducible results. The hybridization to 50 bp amplicons was up to 10 times more efficient than the hybridization to 200 bp amplicons containing the same SNP. Hybridization to individual amplicons in multiplexes was less efficient suggesting that intramolecular and intermolecular interactions may block access to the target sequence on the NanoChip array. We observed a high risk of contamination with amplicons shorter than 60 bp and therefore, we recommend the use of 60-200 bp amplicons for SNP typing analysis on the NanoChip platform. In a comparative study, we typed the 5 Y chromosome loci M173, 92R7, P25, SRY1532, and M9 in 400 males using the NanoChip SNP typing protocol and the SNaPshot kit. Concording results were obtained for all samples demonstrating the accuracy of the NanoChip SNP typing protocol.

Chromosomes, Human, Y↗
PubMed2003

Multiplex PCR and minisequencing of SNPs--a model with 35 Y chromosome SNPs.

We have developed a robust single nucleotide polymorphism (SNPs) typing assay with co-amplification of 25 DNA-fragments and the detection of 35 human Y chromosome SNPs. The sizes of the PCR products ranged from 79 to 186 base pairs. PCR primers were designed to have a theoretical Tm of 60 +/- 5 degrees C at a salt concentration of 180 mM. The sizes of the primers ranged from 19 to 34 nucleotides. The concentration of amplification primers was adjusted to obtain balanced amounts of PCR products in 8mM MgCl2. For routine purposes, 1 ng of genomic DNA was amplified and the lower limit was approximately 100 pg DNA. The minisequencing reactions were performed simultaneously for all 35 SNPs with fluorescently labelled dideoxynucleotides. The size of the minisequencing primers ranged from 19 to 106 nucleotides. The minisequencing reactions were analysed by capillary electrophoresis and multicolour fluorescence detection. Female DNA did not influence the results of Y chromosome SNP typing when added in concentrations more than 300 times the concentrations of male DNA. The frequencies of the 35 SNPs were determined in 194 male Danes. The gene diversity of the SNPs ranged from 0.01 to 0.5.

Chromosomes, Human, Y↗
PubMed2002

Sodium nitroprusside stimulates L-DOPA release from striatal tissue through nitric oxide and cGMP.

The effects of the nitric oxide (NO) donor, sodium nitroprusside, on L-DOPA and dopamine release from striatal tissue were evaluated using a static incubation system in which the striatal tissue released between three and six times more L-DOPA than DA, although the DA content was four times higher than that of L-DOPA. Sodium nitroprusside stimulated L-DOPA release in a time- and concentration-dependent (25, 50 and 100 microM) manner. This effect was not due to an increase in L-DOPA synthesis because sodium nitroprusside did not modify the tyrosine hydroxylase activity of striatal tissue. DA release was also stimulated by sodium nitroprusside but it required a higher concentration (500 microM) and longer incubation (60 min). Neither basal nor sodium nitroprusside-stimulated L-DOPA release was influenced by Ca(2+) deprivation (EGTA 5 mM) and/or the presence of nitrendipine (1 microM), a blocker Ca(2+) channel, in the incubation medium. However, cGMP (1 mM) increased L-DOPA release, and the soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one (ODQ) (5 microM), partially blunted the stimulatory effect of sodium nitroprusside 100 microM. In addition, the presence of certain scavengers of free radicals, such as uric acid (300 microM) or melatonin (300 microM) but not of superoxide dismutase (1000 UI/ml) or salicylic acid (300 microM), completely blocked sodium nitroprusside (100 microM)-induced L-DOPA release. These results show that NO stimulates L-DOPA release from striatal tissue by an apparently Ca(2+)-independent mechanism, mediated by cGMP but also by peroxynitrite.

Animals↗