Jacobsen syndrome: a rare differential diagnosis of multifocal white matter lesions

Introduction: White matter lesions can have many causes. Two half-sisters (same mother) were presented to us for further examination. In both patients Jacobsen syndrome has been diagnosed.

Case Report: First patient, a 2-year-old, showed behavioral problems in addition to mental retardation with hyperactivity and insomnia, facial abnormalities, and a spastic equinus.

Second patient, 17-year-old, also showed mental retardation with facial abnormalities and behavioral problems, such as hyperactivity and insomnia, in past medical history.

In magnetic resonance imaging of the head both patients showed multifocal white matter lesions; in patient 1 particularly subcortical, in patient 2 periventricular in the deep white matter with involvement of the U fibers.

The extensive metabolic investigation, including lysosomal enzymes, very long chain fatty acids, and mitochondrial enzymes, did not lead to any result. The latter was performed in suspicion of a maternal inheritance.

The array-based comparative genomic hybridization (CGH array) showed a 6,7Mb interstitial chromosome deletion of chromosome 11q23.3 – 11q24.2 in both girls, which matches Jacobsen syndrome (partial deletion of the [sub-] terminal end of chromosome 11q). 40% of the Jacobsen region (86 genes) were deleted. The mother has a balanced structural abnormality, in the sense of a paracentric inversion of chromosome 11 in mosaic, which appears to predispose to deletion.

Conclusion: Facing multifocal white matter lesions, rare genetic causes must be taken into consideration in addition to metabolic causes. Some of which, such as the Jacobsen syndrome, can be detected by CGH array investigation. The Jacobsen syndrome is furthermore characterized by mental retardation, behavioral problems, feeding problems, facial abnormalities, heart defects, and thrombocytopenia.