PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “POLG”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2026

Twelve Japanese patients with POLG-related disorders: Population-specific genetic differences of POLG variants in Japan and Europe.

BACKGROUND: POLG encodes mitochondrial DNA (mtDNA) polymerase γ. Pathogenic POLG variants cause mitochondrial diseases, including progressive external ophthalmoplegia. POLG-related disorders are relatively common in Europe, possibly because of the high prevalence of carriers in the general population, but remain rare in Japan for unclear reasons. METHODS: We performed long-range PCR on mtDNA from skeletal muscle and/or peripheral blood from 3146 patients with suspected mitochondrial disease between 1993 and 2021. We selected 167 individuals with clinical features suggestive of POLG-related disorders for POLG gene analysis; all lacked pathogenic mtDNA point mutations, and most had multiple mtDNA deletions and/or a family history of mitochondrial disease. RESULTS: Among the 167 patients (median age: 52 years, range: 0-83 years, 11% pediatric cases), we identified 12 Japanese patients with POLG-related disorders and six POLG variants, including one novel variant. The six variants were p.Y955C, p.R943H, p.T599I, p.M299L, p.Y1210* (c.3626_3629dupGATA), and the novel variant p.F377S (c.1130T>C). Neither these six variants nor the 10 previously reported cases from Japan included the POLG variants that are more frequent in Europe. We also analyzed three population databases: two whole-genome sequencing databases covering 61,000 and 9850 Japanese individuals, respectively, and one global population database (gnomAD) covering 730,000 individuals worldwide. POLG variants that are more frequent in Europe were not detected in the Japanese databases or among East Asian individuals in gnomAD. CONCLUSIONS: Our findings suggest population-specific genetic differences in POLG between Japanese and European populations, explaining the lower frequency of POLG-related disorders in Japan.

CPEO↗
PubMed2025

Charting the phenotypic landscape of mitochondrial diseases through a systematic evaluation of pathogenic mitochondrial DNA and nuclear gene variants.

PURPOSE: Primary mitochondrial diseases (PMD) arise from variants in the mitochondrial or nuclear genomes. Phenotype-based recognition of specific PMD genotypes remains difficult, prolonging the diagnostic odyssey. We expanded the MitoPhen database to characterize phenotypic variation across PMD more systematically. METHODS: Individual-level data on mitochondrial DNA disorders, nuclear-encoded mitochondrial diseases, and single large-scale mitochondrial DNA deletions were manually curated with Human Phenotype Ontology (HPO) terms to produce MitoPhen v2. Principal-component analysis summarized system-level abnormalities; HPO-level enrichment and mean phenotype-similarity scores were then used to distinguish common PMD genotypes. RESULTS: MitoPhen v2 adds 3940 individuals to the original release, now encompassing 1597 publications, 10,626 individuals, and 117 genotypes. Among 7586 affected cases, 72,861 HPO terms were recorded. Principal-component analysis revealed 6 phenotype dimensions capturing most system-level variance. At the HPO level, we observed genotype-specific enrichments and identified 111 gene-phenotype links absent from the current HPO database. Using MT-TL1, single large-scale mitochondrial DNA deletions, and POLG as exemplars, phenotype-similarity scores reliably separated individuals with these genotypes from those without. CONCLUSION: MitoPhen v2 enabled systematic, genotype-aware analysis of heterogeneous PMD phenotypes and highlighted the diagnostic value of structured, individual-level data. Phenotype-similarity metrics from such data sets can refine variant interpretation in large rare-disease cohorts and provide a transferable framework for other phenotypically complex genetic disorders.

Humans↗
PubMedDate not supplied

The freezing of mammalian embryos: perspectives and possibilities.

Since the Ciba Foundation Symposium in 1952 on Mammalian Germ Cells when Dr Audrey Smith reported that 'exposure to very low temperatures is not incompatible with further development of mammalian eggs', much progress has been made on the problem of freezing mammalian embryos. The significant steps leading to this progress are reviewed and an attempt is made to assess the extent of our current knowledge and to relate this to experience gained in other fields of low temperature biology. There is good evidence that certain basic principles concerning cooling and warming rates are applicable to the preservation of all mammalian embryos so far studied, but differences between species and between stages of development within species exist, particularly in their resistance to cooling in temperature ranges above 0 degrees C. Some of these differences are illustrated by reference to experiments with pig embryos. Clearly there are many problems remaining to be solved, but practical applications of techniques for long-term storage of mammalian embryos are already feasible and offer interesting possibilities for future development.

Cryoprotective Agents↗
PubMed1976

The occurrence of C19 steroids in testicular tissue and submaxillary glands of intersex pigs in relation to morphological characteristics.

Five true hermaphrodite pigs and two male pseudohermaphrodite pigs were studied. A 38XX sex chromosome constitution was found in peripheral leucocytes of three true hermaphrodites and in one male pseudohermaphrodite; XX/XY mixoploidy was present in the leucocytes of the remaining male pseudohermaphrodite. The occurrence of C19 steroids, including 16-androstenes, in the testicular tissue and submaxillary gland of intersex pigs was of a similar pattern to that found previously in mature boars, and masculinization of the genital tract was related to the amount of testicular tissue present. It is postulated that in the absence of germ cells in the testicular tissue of intersex pigs the Sertoli cells may be involved in the metabolism of dehydroepiandrosterone to 5-androstenediol, a possible testosterone precursor in the pig. The high levels of 16-androstenes found in the submaxillary gland of intersex pigs indicates that these steroids are responsible for 'boar taint' in these animals. In contrast to the boar, no consistent relationship was found between the occurrence of C19 steroids and the degree of masculinization of the submaxillary gland; it is postulated that the predominantly female genetic constitution may have affected the response of the salivary gland to androgen.

Androstenediols↗
PubMed1976

Deep freezing of sheep embryos.

Sheep embryos, collected 1-8 days after oestrus, were placed in Dulbecco's phosphate-buffered saline medium (PBS). After treatment, the viability of the embryos was tested by temporary transfer to ligated rabbit oviducts. In Exp. 1, Days 5-8 embryos survived for at least 15 min at 0 degrees C in the presence of 1-5 M-DMSO. In Exp. 2, 12/14 Days 5-8 embryos survived after being frozen in 1-5 M-DMSO at 0-3 degrees C/min to temperatures ranging between-15 degrees and -60 degrees C and then thawed at 12 degrees C/min. In Exp. 3, Days 5-8 embryos were frozen in 1-5 M-DMSO at 0-3 degrees C/min to below-65 degrees C before being transferred to liquid nitrogen (-196 degrees C), and stored for 12 hr to 1 month. The embryos were thawed at 3 degrees C/min, 12 degrees C/MIN or 360 degrees C/min and, after transfer to rabbit oviducts, 0/4, 10/36 and 1/4, respectively, developed normally. The 11 embryos which were considered normal when recovered from the rabbit oviducts plus 1 slightly retarded embryo were transferred to 7 recipient ewes. Four ewes subsequently lambed, producing 5 lambs. In addition, 8 embryos were transferred to 4 ewes directly after thawing. Three of these ewes subsequently lambed, producing 3 lambs.

Animals↗
PubMed1976

Artificial insemination with spermatozoa in formaldehyde.

The ability of formaldehyde to preserve the integrity of the membranes of spermatozoa, as indicated by eosin staining (Dott & Foster, 1975), prompted an investigation to discover what other properties of spermatozoa were preserved by low concentrations of formaldehyde in vitro. In a series of experiments on bull, ram and boar spermatozoa it has been shown that spermatozoa rendered immotile by formaldehyde recovered their motility when the formaldehyde was removed by washing up to 12 hr afterwards (H.M. Dott & G.C. Foster, unpublished). To find out if fertility was preserved ewes and sows were inseminated with spermatozoa rendered immotile with formaldehyde.

Animals↗
PubMed1978

The viability of deep-frozen cow embryos.

Day 7 cow embryos were frozen in 1.5 M-DMSO in PBS at 0.3 degrees C/min to -36 degrees C and at 0.1 degrees C/min between -36 and -60 degrees C before being plunged directly into liquid nitrogen. They were subsequently thawed (rapidly to -50 degrees C, at 4 degrees C/min from -50 to -10 degrees C, and rapidly again) to room temperature. Embryonic viability was tested by four different transfer techniques. Maximum pregnancy rate (8/12) was obtained with surgical transfer immediately after thawing and dilution of DMSO.

Animals↗
PubMed1978

A reciprocal translocation, t(6p+; 14q-), in the pig.

A reciprocal translocation, identified as t(6p+; 14q-), is described in a 38,XX intersex pig. It is the fourth reciprocal translocation to be reported for this species, whereas Robertsonian translocations, of frequent occurrence in cattle and sheep, are so far unknown in domestic pig breeds.

Animals↗