Cryptic unbalanced translocation t(17;18)(p13.2;q22.3) identified by subtelomeric FISH and defined by array-based comparative genomic hybridization in a patient with mental retardation and dysmorphic features.
Molecular cytogenetics allows the identification of cryptic chromosome rearrangements, which is clinically useful in mentally retarded and/or dysmorphic individuals with normal results from conventional cytogenetics analysis. We report on a 3-year-old girl with mental retardation, growth deficiency, speech delay, and dysmorphic features including hypertelorism, upslanting palpebral fissures, midfacial hypoplasia, and posteriorly rotated ears. The G-banding analysis showed a 46,XX,t(3;8)(q26.2;p21.1)mat karyotype. However, her clinical features were suggestive of the 18q syndrome. Subtelomeric FISH analysis revealed a der(18) translocated material from chromosome 17. Array-based comparative genomic hybridization (array-CGH) with subtelomeric BAC and PAC clones confirmed the abnormality and refined the breakpoints to 18q22.3-qter and 17p13.2-pter (deletion of 8.5 Mb and duplication of 3.9 Mb, respectively). This case demonstrates the diagnostic utility of combining conventional cytogenetics with molecular chromosome analyses for the identification of subtle chromosome abnormalities.
Hwang
Kwei Shuai
KS
Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
Pearson
Margaret A
MA
Stankiewicz
Pawel
P
Lennon
P Alan
PA
Cooper
M Lance
ML
Wu
Jessica
J
Ou
Zhishuo
Z
Cai
Wei-Wen
WW
Patel
Ankita
A
Cheung
Sau Wai
SW
D000015:Abnormalities, Multiple / Q000235:genetics* / Q000473:pathology; D002675:Child, Preschool; D002871:Chromosome Banding; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics*; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics*; D005145:Face / Q000002:abnormalities*; D005260:Female; D015894:Genome, Human; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D008607:Intellectual Disability / Q000473:pathology*; D007621:Karyotyping; D009693:Nucleic Acid Hybridization / Q000379:methods; D013577:Syndrome; D016615:Telomere / Q000235:genetics; D014178:Translocation, Genetic