Pericentric inversion (13) with two different recombinants in the same family

Area of Science:

• Human Genetics
• Medical Genetics
• Reproductive Genetics

Background:

• Pericentric inversions, such as inv(13)(p11q22), involve a chromosome segment flipping end-to-end.
• These rearrangements can lead to unbalanced gametes during meiosis.

Observation:

• A family presented with an abnormal infant, revealing a pericentric inversion (13) in the father.
• Prenatal diagnosis via amniocentesis identified a recombinant chromosome rec(13)dup p,inv(13)(p11q22) in a subsequent pregnancy.
• A mentally retarded first cousin was found to have a rec(13)dup q,inv(13)(p11q22) karyotype.

Findings:

• The observed fetal abnormalities mirrored those of the first affected child.
• Family studies confirmed the presence of recombinant chromosomes in affected individuals.
• The risk of recombinant offspring for carriers of this specific inversion was estimated to be as high as 40%.

Implications:

• This case highlights the substantial recurrence risk of genetic abnormalities in families with pericentric inversions.
• Accurate karyotyping and genetic counseling are essential for risk assessment and family planning.
• Understanding recombination risks associated with specific inversions aids in prenatal diagnosis and management.