Objective: To make molecular diagnosis of an infant affected with severe developmental delay and multiple birth defects, assisting prenatal diagnosis for the second pregnancy.
Methods: Standard G-banded karyotyping was performed for the fetus and his parents. Single nucleotide polymorphism array (SNP array) was used to detect submicroscopic chromosomal aberration. Fluorescence in situ hybridization (FISH) was employed to determine the parental origin of the aberration.
Results: Both the proband and the fetus harbored a 5.4 Mb distal 4p deletion and a 6.9 Mb distal 6q duplication. FISH confirmed that the mother has carried a balanced translocation involving 4p and 6q.
Conclusion: The unbalanced chromosomal aberration in the proband and the fetus were both derived from the mother. Both patients showed a Wolf-Hirschhorn syndrom phenotype and partial phenotype of 6q trisomy. SNP array combined with FISH are essential for the detection of cryptic chromosomal aberrations which may be missed by coventional karyotyping analysis.