title: Sex difference in leukocyte telomere length is ablated in opposite-sex co-twins.
abstract: BACKGROUND
  In eutherian mammals and in humans, the female fetus may be masculinized while sharing the intra-uterine environment with a male fetus. Telomere length (TL), as expressed in leukocytes, is heritable and is longer in women than in men. The main determinant of leukocyte TL (LTL) is LTL at birth. However, LTL is modified by age-dependent attrition.
  
  
  METHODS
  We studied LTL dynamics (LTL and its attrition) in adult same-sex (monozygotic, n = 268; dizygotic, n = 308) twins and opposite-sex (n = 144) twins. LTL was measured by Southern blots of the terminal restriction fragments.
  
  
  RESULTS
  We observed that in same-sex (both monozygotic and dizygotic) twins, as reported in singletons, LTL was longer in females than in males [estimate ± standard error (SE):163 ± 63 bp, P < 0.01]. However, in opposite-sex twins, female LTL was indistinguishable from that of males (-31 ± 52 bp, P = 0.6), whereas male LTL was not affected. Findings were similar when the comparison was restricted to opposite-sex and same-sex dizygotic twins (females relative to males: same-sex: 188 ± 90 bp, P < 0.05; other-sex: -32 ± 64 bp, P = 0.6).
  
  
  CONCLUSIONS
  These findings are compatible with masculinization of the female fetus in opposite-sex twins. They suggest that the sex difference in LTL, seen in the general population, is largely determined in utero, perhaps by the intrauterine hormonal environment. Further studies in newborn twins are warranted to test this thesis.
authors: Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, Universi
authors: Athanase
authors: A
authors: Benetos
authors: Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark.
authors: Christine
authors: C
authors: Dalgård
authors: Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark.
authors: Carlos
authors: C
authors: Labat
authors: Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark.
authors: Jeremy D
authors: JD
authors: Kark
authors: Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark.
authors: Simon
authors: S
authors: Verhulst
authors: Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, Universi
authors: Kaare
authors: K
authors: Christensen
authors: Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark.
authors: Masayuki
authors: M
authors: Kimura
authors: Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark.
authors: Kent
authors: K
authors: Horvath
authors: Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark.
authors: Kirsten Ohm
authors: KO
authors: Kyvik
authors: Département de Médecine Gériatrique, CHU de Nancy, Nancy, France, INSERM, U1116, Vandoeuvre-les-Nancy, France, Université de Lorraine, Nancy, France, Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark, Hebrew University-Hadassah School of Public Health and Community Medicine, Jerusalem, Israel, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands, Danish Twin Registry, University of Southern Denmark, Odense, Denmark, Department of Clinical Genetics and Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark, Center of Human Development and Aging, State University of New Jersey, Newark, NJ, USA and Institute of Regional Health Services Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark avivab@njms.rutgers.edu.
authors: Abraham
authors: A
authors: Aviv
mesh_terms: D000328:Adult; D000375:Aging / Q000235:genetics*; D015139:Blotting, Southern; D005260:Female; D006801:Humans; D007962:Leukocytes / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D016615:Telomere / Q000378:metabolism*; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*
keywords: Telomeres; men; sex; twins; women