Molecular cytogenetic characterization of an inv dup(15) chromosome presenting as a small supernumerary marker chromosome associated with the inv dup(15) syndrome.

OBJECTIVE: To present molecular cytogenetic characterization of an inverted duplication of proximal chromosome 15 [inv dup(15)] presenting as a small supernumerary marker chromosome (sSMC) associated with the inv dup(15) syndrome.

CASE REPORT: A 35-year-old woman underwent amniocentesis because of advanced maternal age at 27 weeks of gestation, which revealed an sSMC that was confirmed by fluorescence in situ hybridization (FISH) to be derived from chromosome 15. Prenatal ultrasound findings were unremarkable. A 3434-g male baby was delivered at term with no phenotypic abnormalities. The cord blood analysis revealed a bisatellited dicentric inv dup(15). When followed up at 21 years of age, the proband manifested hypotonia, ataxic gait, developmental delay, intellectual disability, epilepsy, poor speech, and autism consistent with the inv dup(15) syndrome. Array comparative genomic hybridization of the peripheral blood revealed arr 15q11.1q13.2 (20,686,219-30,390,043) × 4, 15q13.2q13.3 (30,390,043-32,445,226) × 3. Conventional cytogenetic analysis of the peripheral blood revealed a karyotype of 47,XY,+inv dup(15)(pter→q13::q13→pter). Quantitative fluorescent polymerase chain reaction analysis showed a maternal origin of the inv dup(15) chromosome. FISH analysis confirmed an inv dup(15) chromosome.

CONCLUSION: Molecular cytogenetic techniques are useful for rapid diagnosis of an inv dup(15) chromosome associated with the inv dup(15) syndrome.