Objective: To explore the genetic etiology of a child with moderate mental retardation and multiple malformations.
Methods: The child and his parents underwent conventional G banding karyotype analysis and single nucleotide polymorphism-based mircoarray (SNP-array) scan. A systematic review for chromosome 13q deletions was also conducted to explore the correlation between genotype and clinical phenotypes.
Results: G banding karyotype of the child showed a partial deletion in the long arm of chromosome 13 described as 46,XY,del(13)(q32). SNP-array detected a deletion fragment of 11.367 Mb in 13q32.1-q33.3 region, which encompassed 30 OMIM (Online Mendelian Inheritance in Man) genes including FARP1, STK24 and ZIC2. The parents were found with no obvious abnormality in their karyotypes and SNP-array results, suggesting a de novo origin for the deletion. Combined with previous reported cases, chromosomal 13q deletions seem to have various pathogenic effects on the patients.
Conclusion: Chromosomal 13q32.1-q33.3 deletion probably underlies the disease phenotype in the child, and EFNB2 may be a candidate gene for congenital heart defect, genital malformation, hypospadias and anorectal malformations.