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PubMed1989

Regulation of cellular genes transduced by herpes simplex virus.

Previous studies demonstrated that the rabbit beta-globin gene is transcribed from its own promoter and regulated as a herpes simplex virus (HSV) early gene following insertion into the early HSV thymidine kinase gene in the intact viral genome (J. R. Smiley, C. Smibert, and R. D. Everrett, J. Virol. 61:2368-2377, 1987). We report here that the beta-globin promoter remained under early control after insertion into the late HSV gene encoding glycoprotein C. On the basis of these findings, we concluded that the beta-globin promoter is functionally equivalent to an HSV early-control region. We found that a transduced human alpha-globin gene was also regulated as an early HSV gene, while two linked Alu elements mimicked the behavior of HSV late genes. These results demonstrate that certain aspects of HSV temporal regulation can be duplicated by cellular elements and provide strong support for the hypothesis that the regulation of HSV gene expression can occur through mechanisms that do not rely on recognition of virus-specific temporal control signals.

Animals↗
PubMed1996

The structure of adenovirus type 12 DNA integration sites in the hamster cell genome.

Foreign DNA can integrate into the genomes of mammalian cells, and this process plays major roles in viral oncogenesis and in the generation of transgenic organisms and will be important in evolving regimens for human somatic gene therapy. In the present study, the insertion sites of adenovirus type 12 (Ad12) DNA genomes have been analyzed in detail in the Ad12-transformed hamster cell line T637, its revertants, which have lost most of the >20 Ad12 genome equivalents integrated chromosomally in cell line T637, and in the Ad12-induced tumor T191. Some of these junction sites have been molecularly cloned, and the nucleotide sequences at the sites of transition between viral and cellular DNAs have been determined. The sites of linkage between the hamster cellular and the foreign (viral) DNA are characterized by the frequent occurrence of patch homologies between the recombination partners. The cellular junction sites investigated here are not transcriptionally active. One of the cellular DNA sequences abutting the right Ad12 DNA terminus in cell line T637 (os2) is represented only once in the hamster genome and has a strikingly low abundance of 5'-CG-3' dinucleotide sequences. One 5'-GCGC-3' sequence close to the Ad12 DNA integration site is heavily methylated in normal cells, Ad12-transformed cells, and Ad12-induced tumor cells. The second such sequence is more remote from the junction site, is partly methylated in BHK21 hamster cells, and shows differences in methylation in different Ad12-transformed cell lines. This site is unmethylated in liver DNA. The cellular DNA sequence at the site of Ad12 linkage in the tumor T191 exhibits homologies to highly repetitive sequences of the Alu family and to an origin of hamster DNA replication containing an Alu element. A number of junction sites between Ad12 DNA and hamster or mouse DNA in Ad12-transformed cell lines or Ad12-induced tumor cell lines, investigated here and previously, are characterized by stem-loop structures encompassing the junction sites.

Adenoviridae↗
PubMed2001

HERV-K(OLD): ancestor sequences of the human endogenous retrovirus family HERV-K(HML-2).

Sequences homologous to the human endogenous retrovirus (HERV) family HERV-K(HML-2) are present in all Old World primate species. A previous study showed that a central region of the HERV-K(HML-2) gag genes in Hominoidea species displays a 96-bp deletion compared to the gag genes in lower Old World primates. The more ancient HERV-K(HML-2) sequences present in lower Old World primates were apparently not conserved during hominoid evolution, as opposed to the deletion variants. To further clarify the evolutionary origin of the HERV-K(HML-2) family, we screened GenBank with the 96-bp gag-sequence characteristic of lower Old World primates and identified, to date, 10 human sequence entries harboring either full-length or partially deleted proviral structures, probably representing remnants of a more ancient HERV-K(HML-2) variant. The high degree of mutations demonstrates the long-time presence of these HERV-K(OLD) proviruses in the genome. Nevertheless, they still belong to the HML-2 family as deduced from dot matrix and phylogenetic analyses. We estimate, based on the family ages of integrated Alu elements and on long terminal repeat (LTR) divergence data, that the average age of HERV-K(OLD) proviruses is ca. 28 million years, supporting an integration time before the evolutionary split of Hominoidea from lower Old World primates. Analysis of HERV-K(OLD) LTR sequences led to the distinction of two subgroups, both of which cluster with LTRs belonging to an evolutionarily older cluster. Taken together, our data give further insight into the evolutionary history of the HERV-K(HML-2) family during primate evolution.

Amino Acid Sequence↗
PubMed1993

Alu sequence involvement in transcriptional insulation of the keratin 18 gene in transgenic mice.

The human keratin 18 (K18) gene is expressed in a variety of adult simple epithelial tissues, including liver, intestine, lung, and kidney, but is not normally found in skin, muscle, heart, spleen, or most of the brain. Transgenic animals derived from the cloned K18 gene express the transgene in appropriate tissues at levels directly proportional to the copy number and independently of the sites of integration. We have investigated in transgenic mice the dependence of K18 gene expression on the distal 5' and 3' flanking sequences and upon the RNA polymerase III promoter of an Alu repetitive DNA transcription unit immediately upstream of the K18 promoter. Integration site-independent expression of tandemly duplicated K18 transgenes requires the presence of either an 825-bp fragment of the 5' flanking sequence or the 3.5-kb 3' flanking sequence. Mutation of the RNA polymerase III promoter of the Alu element within the 825-bp fragment abolishes copy number-dependent expression in kidney but does not abolish integration site-independent expression when assayed in the absence of the 3' flanking sequence of the K18 gene. The characteristics of integration site-independent expression and copy number-dependent expression are separable. In addition, the formation of the chromatin state of the K18 gene, which likely restricts the tissue-specific expression of this gene, is not dependent upon the distal flanking sequences of the 10-kb K18 gene but rather may depend on internal regulatory regions of the gene.

Animals↗
PubMed1987

Primate brain-specific cytoplasmic transcript of the Alu repeat family.

A 200-nucleotide RNA homologous to the left monomer of Alu elements was expressed in monkey and human brain and in cell lines but not in nonneural monkey tissues. Similar brain-specific transcription of identifier sequences was observed in rats. Thus, expression of selected repetitive DNA families is a conserved process in mammalian brain.

Animals↗
PubMed2005

Non-hotspot-related breakpoints of common deletions in Sotos syndrome are located within destabilised DNA regions.

BACKGROUND: Sotos syndrome (SoS) is a disorder characterised by excessive growth, typical craniofacial features, and developmental retardation. It is caused by haploinsuffiency of NSD1 at 5q35. There is a 3.0 kb recombination hotspot in which the breakpoints of around 80% of SoS patients with a common deletion can be mapped. OBJECTIVE: To identify deletion breakpoints located outside the SoS recombination hotspot. METHODS: A screening system for the directly orientated segments of the SoS LCRs was developed for 10 SoS patients with a common deletion who were negative for the SoS hotspot. Deletion-junction fragments were analysed for DNA duplex stability and their relation to scaffold/matrix attachment regions (S/MARs). These features were compared with the SoS hotspot and recombination hotspots of other genomic disorders. RESULTS: The breakpoint was mapped in four SoS patients, two with a deletion in the maternally derived chromosome. These breakpoint regions were located approximately 2.5 kb, approximately 9.6 kb, approximately 27.2, and approximately 27.7 kb telomeric to the SoS hotspot and were confined to 164 bp, 46 bp, 256 bp, and 124 bp, respectively. Two of the regions were mapped within Alu elements. All crossover events were found to have occurred within or adjacent to a highly destabilised DNA duplex with a high S/MAR probability. In contrast, the SoS hotspot and other genomic disorders' recombination hotspots were mapped to stabilised DNA helix regions, flanked by destabilised regions with high probability of containing S/MAR elements. CONCLUSIONS: The data suggest that a specific chromatin structure may increase susceptibility for recurrent crossover events and thus predispose to recombination hotspots in genomic disorders.

Abnormalities, Multiple↗
PubMed2006

Genome-wide hypomethylation in human glioblastomas associated with specific copy number alteration, methylenetetrahydrofolate reductase allele status, and increased proliferation.

Genome-wide reduction in 5-methylcytosine is an epigenetic hallmark of human tumorigenesis. Experimentally induced hypomethylation in mice promotes genomic instability and is sufficient to initiate tumorigenesis. Here, we report that global hypomethylation is common in primary human glioblastomas [glioblastoma multiforme (GBM)] and can affect up to an estimated 10 million CpG dinucleotides per haploid tumor genome. Demethylation involves satellite 2 (Sat2) pericentromeric DNA at chromosomes 1 and 16, the subtelomeric repeat sequence D4Z4 at chromosomes 4q and 10q, and interspersed Alu elements. Severe hypomethylation of Sat2 sequences is associated with copy number alterations of the adjacent euchromatin, suggesting that hypomethylation may be one factor predisposing to specific genetic alterations commonly occurring in GBMs. An additional apparent consequence of global hypomethylation is reactivation of the cancer-testis antigen MAGEA1 via promoter demethylation, but only in GBMs and GBM cell lines exhibiting a 5-methylcytosine content below a threshold of approximately 50%. Primary GBMs with significant hypomethylation tended to be heterozygous or homozygous for the low-functioning Val allele of the rate-limiting methyl group metabolism gene methylenetetrahydrofolate reductase (MTHFR), or had a deletion encompassing this gene at 1p36. Tumors with severe genomic hypomethylation also had an elevated proliferation index and deletion of the MTHFR gene. These data suggest a model whereby either excessive cell proliferation in the context of inadequate methyl donor production from MTHFR deficiency promotes genomic hypomethylation and further genomic instability, or that MTHFR deficiency-associated demethylation leads to increased proliferative activity in GBM.

5-Methylcytosine↗
PubMed1990

Structure and distribution of an Alu-type deletion mutation in Sandhoff disease.

Sandhoff disease is a recessively inherited lysosomal storage disease resulting from a deficiency of beta-hexosaminidase activity. The enzyme occurs in two major forms, beta-hexosaminidase A, composed of an alpha- and beta-subunit and beta-hexosaminidase B, composed of two beta-subunits. Both isozyme activities are deficient in Sandhoff disease, owing to mutations of the HEXB gene encoding the common beta-subunit. We have cloned and fully characterized a deletion at the HEXB gene from fibroblasts of a patient with the infantile form of Sandhoff disease. The deletion removes approximately 16 kb of DNA including the HEXB promoter, exons 1-5 and part of intron 5. It most likely arose from recombination between two Alu sequences, with the breakpoints occurring at the midpoint between the left and right arms in each case and regenerating an intact Alu element in the deletion sequence. The deletion allele accounts for 27% of the Sandhoff mutant alleles we analyzed. Two cell lines were shown to be homozygous for the deletion and both had the infantile form of the disease. Four additional patients were compound heterozygotes with other mutations, all of whom displayed a different clinical phenotype. Finally, the mutant allele was present in different ethnic backgrounds, suggesting that it may have been subject to genetic drift.

Base Sequence↗
PubMed2006

Genome-wide sequence and functional analysis of early replicating DNA in normal human fibroblasts.

BACKGROUND: The replication of mammalian genomic DNA during the S phase is a highly coordinated process that occurs in a programmed manner. Recent studies have begun to elucidate the pattern of replication timing on a genomic scale. Using a combination of experimental and computational techniques, we identified a genome-wide set of the earliest replicating sequences. This was accomplished by first creating a cosmid library containing DNA enriched in sequences that replicate early in the S phase of normal human fibroblasts. Clone ends were then sequenced and aligned to the human genome. RESULTS: By clustering adjacent or overlapping early replicating clones, we identified 1759 "islands" averaging 100 kb in length, allowing us to perform the most detailed analysis to date of DNA characteristics and genes contained within early replicating DNA. Islands are enriched in open chromatin, transcription related elements, and Alu repetitive elements, with an underrepresentation of LINE elements. In addition, we found a paucity of LTR retroposons, DNA transposon sequences, and an enrichment in all classes of tandem repeats, except for dinucleotides. CONCLUSION: An analysis of genes associated with islands revealed that nearly half of all genes in the WNT family, and a number of genes in the base excision repair pathway, including four of ten DNA glycosylases, were associated with island sequences. Also, we found an overrepresentation of members of apoptosis-associated genes in very early replicating sequences from both fibroblast and lymphoblastoid cells. These data suggest that there is a temporal pattern of replication for some functionally related genes.

Cell Proliferation↗
PubMed2026

Novel genetic variants identification and immune profiling in ataxia telangiectasia patients.

BACKGROUND: Ataxia telangiectasia (AT) is an autosomal recessive neurodegenerative disease. While heterozygous relatives of AT patients are known to be clinically healthy, a predisposition to various pathologies has been reported. Our aim was firstly, to further characterize the clinical features and broaden the spectrum of genetic pathogenic variants in AT patients. Secondly, we aimed to study the immune profiles of AT patients and their relatives to identify similarities or common biomarkers. METHODS: A Target Gene Sequencing for six patients suspected with AT was performed. Computational analysis was conducted to assess the pathogenicity of novel variants. The distribution of immune cells was assessed by flow cytometry in patients with AT, AT-like disorder, Friedreich ataxia, and in AT relatives. The expression pattern of candidate genes was evaluated by RT-qPCR. RESULTS: We identified and predicted the pathogenicity of novel variants in the ATM gene. Computational analysis suggested that the novel identified missense mutation could affect ATP binding pattern and ATM protein flexibility, while Alu element insertion could probably induces a premature stop codon. Furthermore, our results confirm the pathogenic effect of identified splicing mutations on the ATM transcript. Moreover, we noticed a high percentage of LTCD4 + and LTCD8 + senescent subsets in AT patients and a relative increase of the of intermediate and non-classical monocytes accompanied with a decrease of classical monocytes specifically in AT patients with truncated biallelic mutations which was intriguingly similar to the immune profile of AT parents. In addition, a difference of immune pattern was observed between AT patients with biallelic truncated mutations compared to those with at least one non-truncated mutation, with a variability intragroup. Gene expression analysis identified FOXO3, IL33 and METTL3 as putative genes that may yield clues into AT pathogenesis. CONCLUSION: Taken together, our study expands the mutational spectrum of AT disease worldwide and further characterize the immune profile of AT patients uncovering a possible difference in some immune cellular subsets related to ATM mutation type and delineate putative immune abnormalities related to ATM heterozygosity among AT parents. Furthermore, dysregulation in FOXO3, IL33 and METTL3 expression could be related to disease severity.

Humans↗
PubMed2025

Structural variants linked to Alzheimer's disease and other common age-related clinical and neuropathologic traits.

BACKGROUND: Alzheimer's disease (AD) is a complex neurodegenerative disorder with substantial genetic influence. While genome-wide association studies (GWAS) have identified numerous risk loci for late-onset AD (LOAD), the functional mechanisms underlying most of these associations remain unresolved. Large genomic rearrangements, known as structural variants (SVs), represent a promising avenue for elucidating such mechanisms within some of these loci. METHODS: By leveraging data from two ongoing cohort studies of aging and dementia, the Religious Orders Study and Rush Memory and Aging Project (ROS/MAP), we performed genome-wide association analysis testing 20,205 common SVs from 1088 participants with whole genome sequencing (WGS) data. A range of Alzheimer's disease and other common age-related clinical and neuropathologic traits were examined. RESULTS: First, we mapped SVs across 81 AD risk loci and discovered 22 SVs in linkage disequilibrium (LD) with GWAS lead variants and directly associated with the phenotypes tested. The strongest association was a deletion of an Alu element in the 3'UTR of the TMEM106B gene, in high LD with the respective AD GWAS locus and associated with multiple AD and AD-related disorders (ADRD) phenotypes, including tangles density, TDP-43, and cognitive resilience. The deletion of this element was also linked to lower TMEM106B protein abundance. We also found a 22-kb deletion associated with depression in ROS/MAP and bearing similar association patterns as GWAS SNPs at the IQCK locus. In addition, we leveraged our catalog of SV-GWAS to replicate and characterize independent findings in SV-based GWAS for AD and five other neurodegenerative diseases. Among these findings, we highlight the replication of genome-wide significant SVs for progressive supranuclear palsy (PSP), including markers for the 17q21.31 MAPT locus inversion and a 1483-bp deletion at the CYP2A13 locus, along with other suggestive associations, such as a 994-bp duplication in the LMNTD1 locus, suggestively linked to AD and a 3958-bp deletion at the DOCK5 locus linked to Lewy body disease (LBD) (P = 3.36 × 10-4). CONCLUSIONS: While still limited in sample size, this study highlights the utility of including analysis of SVs for elucidating mechanisms underlying GWAS loci and provides a valuable resource for the characterization of the effects of SVs in neurodegenerative disease pathogenesis.

Humans↗
PubMed2006

Inhibitors of DNA methylation and histone deacetylation independently relieve AML1/ETO-mediated lysozyme repression.

The human lysozyme (LZM) gene is highly methylated in LZM-nonexpressor immature myeloid and in nonmyeloid cells and unmethylated only in LZM-expressing cells. Extended methylation analyses of the CpG-poor 5' flanking region and of the exon 4 CpG island (both containing Alu elements) of the LZM gene were now performed. Marked demethylation was noted after treatment of AML1/ETO-positive Kasumi-1 cells with the DNA methyltransferase (DNMT) inhibitor 5-aza-2'-deoxycytidine (5-azaCdR), not associated with cellular differentiation. LZM mRNA in Kasumi-1, but not in several AML1/ETO-negative myeloid cell lines, was specifically and independently up-regulated upon treatment with 5-azaCdR and, to a lesser extent, with the histone deacetylase (HDAC) inhibitor trichostatin A (TSA). Increased chromatin accessibility within the 5' LZM gene was observed concomitantly with 5-azaCdR-induced demethylation. In contrast, TSA treatment had no effect on chromatin accessibility, but, as shown by chromatin immunoprecipitation, resulted in increased acetylation of histones H3 and H4. Repression of LZM transcription is mediated by conditional AML1/ETO expression in an inducible cell line model (U-937), and is reversed by siRNA "knock-down" of AML1/ETO in Kasumi-1 cells (Dunne et al., Oncogene 25: 2006). Antagonization of LZM repression following conditional expression of AML1/ETO was achieved by TSA. In conclusion, we demonstrate complex interactions between DNA methylation and histone modifications in mediating LZM repression, which implicate AML1/ETO as one component involved in local chromatin remodeling. Interestingly, inhibitors of DNMTs and HDACs independently relieve repression of this CpG-poor gene in AML1/ETO-positive cells.

Acetylation↗
PubMed2002

Angiotensin converting enzyme gene insertion/deletion polymorphism and cardiovascular disease: therapeutic implications.

Cardiovascular disease is the major cause of morbidity and mortality in Westernised societies. It is well known that the aetiology of this devastating disorder involves both genetic and environmental factors. Sequence variants of the components of the renin-angiotensin-aldosterone system and the kallikrein-kinin system are suggested to have significant influences on cardiovascular homeostasis. Both gene targeting and transgenic studies in mice have clearly suggested a critical role of the angiotensin converting enzyme (ACE) gene in blood pressure regulation. Furthermore, an up-regulation of myocardial ACE gene expression has been observed in patients with heart failure. Thus, the ACE gene has been recognised as a top candidate gene for cardiovascular research. Over the past decade, the insertion/deletion (I/D) polymorphism of a 287-bp Alu element in intron 16 of the ACE gene has attracted significant attention and has been extensively investigated in a spectrum of cardiovascular phenotypes, because of its correlation with serum ACE activity. A large majority of previous studies have shown a positive association between the DD genotype and an increased risk of myocardial infarction, but results in hypertension, left ventricular hypertrophy, cardiomyopathy and restenosis after percutaneous transluminal coronary angioplasty remain quite controversial. Since ACE inhibitors are widely used in hypertension and congestive heart failure, we also review the literature on the relationship of ACE I/D polymorphism with ACE inhibitor response. It appears that this polymorphism has some moderate impact on the cardiovascular response to ACE inhibitors but there is no consensus as to which allele confers a more pronounced effect. In addition, previous data are suggestive of an association between the ACE I allele and a greater risk of increased occurrence of ACE inhibitor-induced cough, but such a relationship needs further confirmation. Overall, since ACE I/D is only an intronic marker, the true locus that controls the ACE enzyme activity remains to be identified, and could be located within either the ACE gene or another nearby gene such as the human growth hormone gene. We note that since associations tend to vary across different gender or ethnic groups, or across different socio-ecological settings, consideration of potential gene-gene and gene-environment interactions should be made. Furthermore, the dissection of the genetic underpinning of cardiovascular disease needs delineation of all molecular variants of the key physiological pathways that influence cardiovascular function.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

Sequence and gene content in 52 kb including and centromeric to the G6PD gene in Xq28.

A cosmid containing 36.4 kb of high GC human DNA centromeric to the G6PD gene has been analyzed. The sequence was 99.9% precise, based on the comparison of 4.3 kb that overlaps an earlier analysis of 20.1 kb containing G6PD. Properties of the entire 52 kb region that may be characteristic of high GC portions of the genome include a very high density of sixty-two half or full Alu sequences, or 1.2/kb, and an absence of L1 sequences. Other highly repetitive sequences include 11 MER sequences, one of them interrupted at two positions by groups of 3 Alu elements. In segments of unique sequence, computer-aided analysis predicted three possible genes, one of which has thus far been confirmed by the recovery of a corresponding cDNA, both by a direct hybridization method and by a PCR-based method based on a primer pair inferred from the genomic sequence. The cDNA has been sequenced, and is completely concordant with counterpart genomic sequence; it has no resemblance to any previously described gene.

Base Sequence↗
PubMed2026

Combined effects of urine exposure and cryopreservation on sperm quality: an in vitro study of retrograde ejaculation.

Sperm quality influences fertility and offspring health through both genomic inheritance and epigenetic inheritance. Thus, for use in clinical-assisted reproductive technology (ART), spermatozoa must have optimal genomic and epigenetic structures. In patients with retrograde ejaculation, spermatozoa are usually recovered from urine and then cryopreserved for ART. However, the effects of urine exposure and subsequent freeze-thaw cycles on sperm quality remain unclear. This is particularly true for epigenetic changes and their underlying mechanisms. In this study, we examined how different durations of urine exposure (10 min and 40 min) followed by freeze-thaw cycles affected sperm motility, DNA integrity, and methylation levels of imprinting genes (H19-imprinted maternally expressed transcript [ H19 ], mesoderm-specific transcript [ MEST ], and the transposable element Alu [ Alu ]). As the duration of urine exposure increased, sperm motility (median [interquartile range]) decreased from 48.0% (39.0%-52.5%) to 1.0% (1.0%-5.0%), the DNA fragmentation index (DFI; median [interquartile range]) increased from 12.0% (9.3%-19.9%) to 23.5% (13.9%-33.9%), the MEST methylation level (mean ± standard deviation [s.d.]) increased from 3.8% ± 1.5% to 11.5 ± 1.2%, and the H19 methylation level (mean ± s.d.) decreased from 86.9% ± 0.9% to 82.1% ± 0.5%. The freeze-thaw process further reduced sperm motility, while the DFI and methylation levels of MEST and H19 did not significantly change. The Alu methylation level remained stable. These findings demonstrate that urine exposure affects sperm motility, DNA integrity, and methylation levels of some imprinting genes. These effects intensify over time. In contrast, the freeze-thaw process impacts only sperm motility. In clinical practice, minimizing exposure to urine might improve sperm quality.

Humans↗
PubMed1999

Analysis of the region of the 5' end of the MLL gene involved in genomic duplication events.

Rearrangements of the MLL gene are associated with both myeloid and lymphoid acute leukaemia. The gene is commonly involved in reciprocal translocations leading to the creation of chimaeric genes encoding novel protein products. An alternative mechanism of MLL gene rearrangement is due to intragenic duplication, leading to partial duplication of the amino-terminal portion of the protein. This occurs in leukaemia, but it has recently been shown that partial duplications of the MLL gene are detectable in peripheral blood and bone marrow of healthy donors and in normal non-haemopoietic tissues. Sequence analysis of the 45 kb of the 5' end of the MLL locus encompassing the breakpoints of these genomic duplications has failed to show a definitive reason as to why this region is such a frequent target of rearrangement. Indeed, although the majority of the breakpoint joins are the result of apparent Alu-mediated homologous recombination, several joins do not involve Alu elements in the region, despite a high density of these repetitive elements in the sequence.

Base Sequence↗
PubMed2000

Clinal variation of YAP+ Y-chromosome frequencies in Western Iberia.

The potential of Y-chromosome biallelic marker haplotypes to infer population affiliations and structures was exploited to analyze four populations from the southwestern edge of Europe, namely north, central, and south Portugal and Galicia. Three markers subdividing the YAP+ lineage were analyzed: the YAP Alu element insertion itself and the SRY8299 and sY81 base substitutions; these respectively define three haplotypes known as 4, 21, and 8. Only haplotype 21 was detected presenting an increasing north-to-south frequency gradient, from 9.6% (Galicia) to 24.5% (South Portugal). This clinal distribution most likely reflects the genetic input associated with the Neolithic spread of agriculture, but we cannot exclude other movements as potential contributors to the distribution. In this context, it is interesting to note the consistency between the clinal variation and the population movement associated with Islamic rule in Iberia. The absence of haplotype 8, a marker of sub-Saharan populations, suggests that, despite the massive introductions of African slaves in historical times, there was little admixture between the African males and Western Iberian populations.

Gene Frequency↗
PubMed2001

Gene structure of the human DDX3 and chromosome mapping of its related sequences.

The human DDX3 gene (GenBank accession No. U50553) is the human homologue of the mouse Ddx3 gene and is a member of the gene family that contains DEAD motifs. Previously, we mapped the gene to the Xp11.3-11.23. In this report, we describe the structural organization of the human DDX3 gene. It consisted of 17 exons that span approximately 16 kb. An Alu element was present in the intron 13. Its organization was the same as that of the human DBY gene, a closely related sequence present on the Y chromosome. We also identified two processed pseudogenes (DDX3) with a sequence that is highly homologous to those of DDX3 cDNAs, but contain a translation termination codon within its open-reading frame. Pseudogenes are mapped on human chromosomes 4 and X, respectively. In this paper, we discuss the relationships between DDX3 and its related sequences that have been isolated.

Amino Acid Sequence↗