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Recombinant chromosome 7 in a mosaic 45,X/47,XXX patient

Carlos A Tirado1, Garrett Gotway, Emmanuel Torgbe

  • 1Laboratory of Clinical Cytogenetics, Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas, USA. ctirado@mednet.ucla.edu

American Journal of Medical Genetics. Part A
|November 23, 2011
PubMed

Insights

A newborn with birth defects had a unique chromosomal abnormality. This rare genetic condition in the father led to a deletion on chromosome 7 in the child, causing developmental issues.

Area of Science:

  • Human Genetics
  • Reproductive Genetics
  • Clinical Cytogenetics

Background:

  • Paracentric inversions can lead to unbalanced gametes and offspring with chromosomal abnormalities.
  • Pericentric inversions pose risks for chromosomal gains and losses in offspring.

Observation:

  • A newborn presented with dysmorphic features and malformations.
  • Initial karyotyping revealed add(7)(q32) and mos 45,X/47,XXX.
  • Array comparative genomic hybridization (CGH) identified an interstitial deletion in chromosome 7 long arm (bands q35-q36.3).

Findings:

  • The patient's deletion resulted from meiotic recombination in the father's paracentric inversions on chromosome 7.
  • The father carries a unique, previously unreported karyotype: rec(7)(7pter->q35::q36.3->7qter)pat and der(7)(7pter->q22.1::q36.3->q35::q22.1->q35::q36.3->7qter).
  • This specific chromosomal arrangement predisposes to deletions or duplications in the 7q35-36 region.

Implications:

  • This case highlights a novel mechanism for generating deletions on chromosome 7 due to parental paracentric inversions.
  • Understanding such unique karyotypes is crucial for accurate genetic counseling and risk assessment in families.
  • Further research into complex chromosomal rearrangements can improve diagnosis of congenital anomalies.

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