[Analysis of a female with a peripheral blood lymphocytic karyotype of trisomy 18 but normal intelligence].

OBJECTIVE: To explore the genetic basis for a female with a peripheral lymphocyte karyotype of trisomy 18 but normal intelligence. METHODS: G-banding karyotype analysis, fluorescence in situ hybridization (FISH) and single nucleotide polymorphism microarray (SNP array) were employed to analyze the peripheral blood sample and buccal cells from the patient. RESULTS: Chromosomal karyotyping, SNP array and FISH analysis of the patient's peripheral blood all suggested 47,XX,+18. Interphase FISH analysis of buccal cells, however, revealed presence of 45,X and low percentage of trisomy 18 and monosomy 18. CONCLUSION: The clinical manifestation of germ layer chromosomal mosaicism is complex. The impact of the genetic disorder on the individual will depend on the structure and function derived from the affected germ layer.