ABSTRACT
The human genome contains many submicroscopic copy number variations which includes deletions, duplications and insertions. Although conventional karyotyping remains an important diagnostic tool in evaluating a dysmorphic patient with mental retardation, molecular diagnostic technology such as array comparative genomic hybridization (aCGH) has proven to be sensitive and reliable in detecting these submicroscopic anomalies. A 3 month-old infant with dysmorphic facies, microcephaly and global developmental delay was referred for genetic evaluation. Preliminary karyotyping which was confounded by the quality of metaphase spread was normal; however, aCGH detected a 30.6Mb deletion from 5p15.33-p13.3. This case illustrates the usefulness of aCGH as an adjunctive investigative tool for detecting chromosomal imbalances.
ABSTRACT
A 15q25-qter partial trisomy characterized by pre or postnatal overgrowth, tall stature, macrocephaly and craniosynostosis has rarely been reported. The cause of overgrowth has been thought to be the triplication of the insulin-like growth factor 1 receptor (IGF1R) gene located on the 15q26.3. We report a patient with partial trisomy 15q25.3-qter showing mental retardation, developmental delay, macrocephaly, long narrow face, ptosis, high palate arch, scoliosis, clinodactyly and overgrowth. Additional material located on terminal 2q was found in karyotyping analysis. In bacterial artificial chromosome (BAC) clone-based-array comparative genomic hybridization (aCGH) analysis, a gain of 31 clones on 15q25.3-qter and a loss of 2 clones on 2q37.3 were observed. An extra copy of IGF1R gene was observed on derivative chromosome 2 in FISH analysis. In conclusion, the patient was diagnosed to have de novo 46,XX,der(2)t(2;15)(q37.3;q25.3) chromosome complement. Adequate genetic counseling and regular follow-ups would be needed for the patient.