title: Genetic and molecular analysis of a new unbalanced X;18 rearrangement: localization of the diminished ovarian reserve disease locus in the distal Xq POF1 region.
abstract: BACKGROUND
  Diminished ovarian reserve (DOR) is a heterogeneous disorder causing infertility, characterized by a decreased number of oocytes, the genetic cause of which is still unknown.
  
  
  RESULTS
  We describe a family with a new unbalanced X;18 translocation der(X) associated with either fully attenuated or DOR phenotype in the same family. Cytogenetics and array comparative genomic hybridization (aCGH) studies have revealed the same partial Xq monosomy and partial 18q trisomy in both the 32-year-old female with DOR and the unaffected mother. The genetic analysis has defined a subtelomeric deletion spanning 13.3 Mb from Xq27.3 to -Xqter, which covers the premature ovarian failure locus 1 (POF1); and a duplication spanning 13.4 Mb, from 18q22.1 to 18qter. From a parental-origin study, we have inferred that the rearranged X chromosome is maternally derived. The Xq27 and 18q22 breakpoint regions fall in a region extremely rich in long interspersed nuclear element, a class of retrotransposons able to trigger mispairing and unusual crossovers. X-inactivation studies reveal a skewing of der(X) both in the mother and the proband. Therefore, the phenotypic expression of der(X) is fully attenuated in the fertile mother and partially attenuated in the DOR daughter.
  
  
  CONCLUSIONS
  We report on an unbalanced maternally derived translocation (X;18)(q27;q22) with different intra-familial reproductive performances, ranging from fertility to DOR. Skewed X-inactivation seems to restore the unbalanced genetic make-up, fully silencing the 18q22 trisomy and at least in part the Xq27 monosomy. The chromosomal abnormality observed in this family supports the presence of a DOR susceptibility locus in the distal Xq region and targets the POF1 region for further investigation.
authors.affiliation: Institute of Genetics and Biophysics Adriano Buzzati Traverso CNR, Via Pietro Castellino, 111, 80131 Naples, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Fusco
authors.forename: Mariateresa
authors.initials: M
authors.lastname: Paciolla
authors.forename: Emily
authors.initials: E
authors.lastname: Chen
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.forename: Rita
authors.initials: R
authors.lastname: Genesio
authors.forename: Anna
authors.initials: A
authors.lastname: Conti
authors.forename: Julie
authors.initials: J
authors.lastname: Jones
authors.forename: Loredana
authors.initials: L
authors.lastname: Poeta
authors.forename: Maria Brigida
authors.initials: MB
authors.lastname: Lioi
authors.forename: Matilde Valeria
authors.initials: MV
authors.lastname: Ursini
authors.forename: Maria Giuseppina
authors.initials: MG
authors.lastname: Miano
mesh_terms: D000293:Adolescent; D000328:Adult; D002467:Cell Nucleus / Q000378:metabolism; D002869:Chromosome Aberrations; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics*; D041321:Chromosomes, Human, X / Q000235:genetics*; D005260:Female; D020868:Gene Silencing; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D008875:Middle Aged; D009693:Nucleic Acid Hybridization; D009865:Oocytes / Q000166:cytology; D010049:Ovarian Diseases / Q000235:genetics*; D010053:Ovary / Q000502:physiology*; D010641:Phenotype; D016649:Primary Ovarian Insufficiency / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D014314:Trisomy / Q000235:genetics