Schizophrenia and nail patella syndrome: The dopamine connection

Background: Nail-patella syndrome (NPS) is characterized by changes in the nails, knees, and elbows, as well as the presence of iliac horns detected by X-ray of the pelvis. A higher occurrence of psychiatric disorders has also been suggested in NPS. Heterozygous mutations in the gene encoding the LIM-homeodomain transcription factor (LMX1B) are identified in most patients with typical clinical findings of NPS. Objective: To report on the association between NPS and schizophrenia. Methods: Genomic DNA was isolated from a patient’s venous blood and collected on ethylenediaminetetraacetic 5% with the Gentra Puregene Blood Kit. All exons and flanking regions of the LMX1B gene (LMX1B: NM_001174146.1) were amplified by standard polymerase chain reaction and analyzed by direct DNA sequencing with BigDye Terminators on an ABI 3100 sequencer. Sequence chromatograms were analyzed using SeqScape software version 1.1. Mutation analysis and characterization of variants was performed with the Alamut Software Version 2.1. Results: We report a patient presenting to the psychiatry department wi th schi zophreni a. Cl i ni cal exami nati on revealed characteristic findings consistent with NPS. Since NPS was suspected, based on clinical findings, sequencing of all coding exons of LMX1B gene was completed. Results revealed a novel heterozygous mutation in the proband: c.546_547insACCG(het); p.Glu183Thrfs*11. Conclusions: Based on LMX1B expression in brain regions that are implicated in neuropsychiatric illness, and especially in the development of dopaminergic neurons, we hypothesize that schizophrenia may be part of the clinical spectrum of NPS.