[Unbalanced translocation t (5;15) in a patient with Prader-Willi syndrome]

To diagnose and detect the molecular defect in a suspected patient with Prader-Willi syndrome.

Genetic diagnosis and molecular genetic analysis were performed by using chromosome karyotype analysis, methylation-specific PCR (MS-PCR), and linkage analysis using short tandem repeat (STR).

The karyotype of the patient was 45, XX, der(5), t(5;15)(q35;q13), -15, and the parents were 46, XY and 46, XX, respectively, implying that the unbalanced translocation t(5;15) in the patient was de novo. Furthermore, MS-PCR and STR linkage analysis confirmed that the patient's 15q11-13 deletion was resulted from unbalanced translocation on paternal chromosome 15.

Genetic analysis should be applied in suspected patients with Prader-Willi syndrome to confirm the diagnosis. Cytogenetic and molecular techniques would be helpful in clinical diagnosis, genetic counseling and prenatal diagnosis.