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A de novo translocation, 14q21q, with a microchromosome-14p21p
Insights
A rare familial translocation t(14;21) was identified in a mother and child, linked to a Down syndrome birth. This genetic event suggests a 1:3 segregation pattern during maternal meiosis.
Area of Science:
- Genetics
- Cytogenetics
- Human Genetics
Background:
- Familial chromosomal translocations can lead to unbalanced karyotypes and genetic disorders in offspring.
- Down syndrome (Trisomy 21) is typically caused by an extra copy of chromosome 21.
Observation:
- A mother and child presented with a rare familial translocation, t(14;21)(14p21p;14q21q).
- The translocation was identified following the birth of a baby with Down syndrome and a complex karyotype: 47,XX,-14,+der 14,+der 21,t(14;21)(q11;p12)mat.
Findings:
- The study describes a unique t(14;21) translocation involving both pericentromeric (14p21p) and long arm (14q21q) regions.
- The observed 1:3 segregation pattern in maternal meiosis provides insight into the inheritance of this unbalanced chromosomal state.
- The translocated chromosome 14q21q resembles a Robertsonian translocation product, while the 14p21p chromosome appears as a satellited microchromosome.
Implications:
- This case highlights the importance of cytogenetic analysis in understanding complex familial translocations and their association with genetic syndromes.
- The findings contribute to the understanding of meiotic segregation patterns in carriers of balanced translocations.
- Further characterization of such rare translocations is crucial for accurate genetic counseling and risk assessment in affected families.
Abstract:
A familial translocation, t(14;21)(14p21p;14q21q), in a mother and her child is described. The translocation was ascertained through the birth of a Down syndrome baby with the chromosome constitution 47,XX,-14, +der 14, +der 21,t(14;21)(q11;p12) mat. A 1:3 segregation in the maternal meiosis is suggested for the evolution of the unbalanced chromosome state. The main translocated chromosome 14q21q mimics the product of a Robertsonian translocation, while the 14p21p chromosome has the morphology of a satellited microchromosome. The cytogenetic nature of this translocation is discussed.