The methylation status of young Alu sequences was investigated in four ICF patients. In fibroblast and leukocyte DNAs, Alu repeats were either undermethylated (HhaI and HpaII digestion) or demethylated (BstUI digestion), in contrast with the methylated status of Alus in control subjects. The methylation profile exhibited in ICF patients reproduces the normal profile of placental or sperm DNA. High-sensitivity immunocytochemical detection of HhaI and HpaII restriction sites on metaphase chromosomes provided further evidence of this undermethylation. The DNA methylation defect in ICF patients, first detected in satellite DNAs (constitutive heterochromatin) and CpG islands of genes on the inactive X chromosome (facultative heterochromatin), thus includes Alu sequences that are widely distributed throughout the human genome.
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http://dx.doi.org/10.1159/000134605 | DOI Listing |
Nat Commun
January 2025
Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
Studies of the genetics of Alzheimer's disease (AD) have largely focused on single nucleotide variants and short insertions/deletions. However, most of the disease heritability has yet to be uncovered, suggesting that there is substantial genetic risk conferred by other forms of genetic variation. There are over one million short tandem repeats (STRs) in the genome, and their link to AD risk has not been assessed.
View Article and Find Full Text PDFSci Rep
January 2025
Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove, #04-06 Immunos, Singapore, 138648, Singapore.
The tumor suppressor LKB1/STK11 plays important roles in regulating cellular metabolism and stress responses and its mutations are associated with various cancers. We recently identified a novel exon 1b within intron 1 of human LKB1/STK11, which generates an alternatively spliced, mitochondria-targeting LKB1 isoform important for regulating mitochondrial oxidative stress. Here we examined the formation of this novel exon 1b and uncovered its relatively late emergence during evolution.
View Article and Find Full Text PDFelements are primate-specific retrotransposon sequences that comprise ∼11% of human genomic DNA. sequences contain an internal RNA polymerase III promoter and the resultant RNA transcripts mobilize by a replicative process termed retrotransposition. retrotransposition requires the Long INterspersed Element-1 (LINE-1) open reading frame 2-encoded protein (ORF2p).
View Article and Find Full Text PDFJ Clin Lipidol
December 2024
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India; Apollo Genomics Institute, Indraprastha Apollo Hospital, New Delhi, 110076, India. Electronic address:
Background: Homozygous familial hypercholesterolemia (HoFH) is a severe form of familial hypercholesterolemia (FH), characterized by high low-density lipoprotein cholesterol (LDL-C) levels and increased coronary artery disease risk. This study reports a novel Alu insertion in the LDLR gene in a consanguineous Indian family, causing FH.
Objective: To identify and characterize the mutation causing HoFH in a proband and their family members.
Comput Struct Biotechnol J
December 2024
Institute for Personalized Medicine, Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, USA.
Nullomers are short DNA sequences (11-18 base pairs) that are absent from a genome; however, they can emerge due to mutations. Here, we characterize all possible putative human nullomer-emerging single base pair mutations, population variants and disease-causing mutations. We find that the primary determinants of nullomer emergence in the human genome are the presence of CpG dinucleotides and methylated cytosines.
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