Intrachromosomal triplication for the distal part of chromosome 15q

Am J Med Genet A. 2005 Jul 15;136(2):179-84. doi: 10.1002/ajmg.a.30745.


We report the case of a boy whose karyotype at birth showed additional material on one chromosome 15. He underwent treatment for unilateral nephroblastoma at 6 years old. At 23 years old, he presented with body asymmetry, facial dysmorphism, arachnodactyly, severe scoliosis, and mental retardation. Molecular cytogenetic analyses of peripheral lymphocytes demonstrated a complex mosaic with three clones. A major cell lineage (68%) showed a chromosome 15 with additional material fused to its telomere long arm that was constituted by an inverted duplicated 15q24.3-qter segment. Therefore, the resulting add(15)(q) harbored an intrachromosomal triplication with the middle segment being inverted in orientation. A minor cell lineage (7%) showed an abnormal chromosome 3 resulting from a telomeric fusion between its short arm and an inverted duplicated 15q24.3-qter segment. The third cell lineage (25%) showed a normal 46,XY constitution. Finally, this resulted in tetrasomy for the distal 15q24.3-qter region in 75% of the patient's lymphocytes. To our knowledge, distal 15q tetrasomy is rare and only eight cases have been reported in the literature, all due to a supernumerary analphoid marker consisting of an inverted duplication. We report here the first observation of distal 15q tetrasomy associated with a 46 chromosomes constitution. We compare the phenotype of our patient to previous cases of distal tetrasomy 15q and discuss the mechanisms underlying this chromosomal rearrangement.

Publication types

  • Case Reports
  • Review

MeSH terms

  • Abnormalities, Multiple / genetics*
  • Abnormalities, Multiple / pathology
  • Adult
  • Child
  • Chromosome Aberrations*
  • Chromosome Banding
  • Chromosomes, Human, Pair 15 / genetics*
  • Face / abnormalities
  • Follow-Up Studies
  • Humans
  • In Situ Hybridization, Fluorescence
  • Infant, Newborn
  • Intellectual Disability / pathology
  • Karyotyping
  • Male
  • Mosaicism
  • Phenotype
  • Scoliosis / pathology
  • Wilms Tumor / pathology