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Partial 1q and 21p trisomies in a male child due to maternal t(1;21)

S Rajangam1, S Lincoln, S Hegde

  • 1Department of Anatomy, St. John's Medical College, Bangalore.

Indian Journal of Pediatrics
|May 8, 2000
PubMed

Insights

This case study details a 7-year-old boy with Down syndrome due to a rare Robertsonian translocation involving chromosomes 1 and 21. The genetic finding, t(1;21)(q32;q11)mat, was inherited from his mother.

Area of Science:

  • Genetics
  • Cytogenetics
  • Human Genetics

Background:

  • Cytogenetic investigations are crucial for diagnosing chromosomal abnormalities.
  • Translocations, particularly Robertsonian translocations, can lead to aneuploidy and genetic disorders.
  • Maternal inheritance of chromosomal rearrangements requires careful genetic counseling.

Observation:

  • A 7-year-old male proband presented for cytogenetic analysis.
  • Karyotype analysis revealed an extra derivative chromosome 21.
  • The specific chromosomal rearrangement identified was a reciprocal translocation between chromosomes 1 and 21, denoted as t(1;21)(q32;q11).

Findings:

  • The proband's karyotype was determined to be 47, XY + der(21), t(1;21)(q32;q11)mat.
  • This indicates trisomy 21 due to a translocation, specifically an unbalanced Robertsonian translocation.
  • The translocation was confirmed to be of maternal origin (mat).

Implications:

  • This genetic finding explains the proband's condition, likely Down syndrome, and highlights the importance of parental origin in chromosomal abnormalities.
  • Understanding the specific translocation is vital for accurate genetic counseling regarding recurrence risks and family planning.
  • Further research into the phenotypic impact of this specific t(1;21) translocation can refine clinical management and understanding of Down syndrome variations.

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