Congenital diaphragmatic hernia and chromosome 15q26: determination of a candidate region by use of fluorescent in situ hybridization and array-based comparative genomic hybridization

Congenital diaphragmatic hernia (CDH) has an incidence of 1 in 3,000 births and a high mortality rate (33%-58%). Multifactorial inheritance, teratogenic agents, and genetic abnormalities have all been suggested as possible etiologic factors. To define candidate regions for CDH, we analyzed cytogenetic data collected on 200 CDH cases, of which 7% and 5% showed numerical and structural abnormalities, respectively. This study focused on the most frequent structural anomaly found: a deletion on chromosome 15q. We analyzed material from three of our patients and from four previously published patients with CDH and a 15q deletion. By using array-based comparative genomic hybridization and fluorescent in situ hybridization to determine the boundaries of the deletions and by including data from two individuals with terminal 15q deletions but without CDH, we were able to exclude a substantial portion of the telomeric region from the genetic etiology of this disorder. Moreover, one patient with CDH harbored a small interstitial deletion. Together, these findings allowed us to define a minimal deletion region of approximately 5 Mb at chromosome 15q26.1-26.2. The region contains four known genes, of which two--NR2F2 and CHD2--are particularly intriguing gene candidates for CDH

Loss of Nuclear Activity of the FBXO7 Protein in Patients with Parkinsonian-Pyramidal Syndrome (PARK15)

Mutations in the F-box only protein 7 gene (FBXO7) cause PARK15, an autosomal recessive neurodegenerative disease presenting with severe levodopa-responsive parkinsonism and pyramidal disturbances. Understanding the PARK15 pathogenesis might thus provide clues on the mechanisms of maintenance of brain dopaminergic neurons, the same which are lost in Parkinson's disease. The protein(s) encoded by FBXO7 remain very poorly characterized. Here, we show that two protein isoforms are expressed from the FBXO7 gene in normal human cells. The isoform 1 is more abundant, particularly in primary skin fibroblasts. Both isoforms are undetectable in cell lines from the PARK15 patient of an Italian family; the isoform 1 is undetectable and the isoform 2 is severely decreased in the patients from a Dutch PARK15 family. In human cell lines and mouse primary neurons, the endogenous or over-expressed, wild type FBXO7 isoform 1 displays mostly a diffuse nuclear localization. An intact N-terminus is needed for the nuclear FBXO7 localization, as N-terminal modification by PARK15-linked missense mutation, or N-terminus tag leads to cytoplasmic mislocalization. Furthermore, the N-terminus of wild type FBXO7 (but not of mutant FBXO7) is able to confer nuclear localization to profilin (a cytoplasmic protein). Our data also suggest that overexpressed mutant FBXO7 proteins (T22M, R378G and R498X) have decreased stability compared to their wild type counterpart. In human brain, FBXO7 immunoreactivity was highest in the nuclei of neurons throughout the cerebral cortex, intermediate in the globus pallidum and the substantia nigra, and lowest in the hippocampus and cerebellum. In conclusion, the common cellular abnormality found in the PARK15 patients from the Dutch and Italian families is the depletion of the FBXO7 isoform 1, which normally localizes in the cell nucleus. The activity of FBXO7 in the nucleus appears therefore crucial for the maintenance of brain neurons and the pathogenesis of PARK15