The complete inability to sense pain in an otherwise healthy individual is a very rare phenotype. In three consanguineous families from northern Pakistan, we mapped the condition as an autosomal-recessive trait to chromosome 2q24.3. This region contains the gene SCN9A, encoding the alpha-subunit of the voltage-gated sodium channel, Na(v)1.7, which is strongly expressed in nociceptive neurons. Sequence analysis of SCN9A in affected individuals revealed three distinct homozygous nonsense mutations (S459X, I767X and W897X). We show that these mutations cause loss of function of Na(v)1.7 by co-expression of wild-type or mutant human Na(v)1.7 with sodium channel beta(1) and beta(2) subunits in HEK293 cells. In cells expressing mutant Na(v)1.7, the currents were no greater than background. Our data suggest that SCN9A is an essential and non-redundant requirement for nociception in humans. These findings should stimulate the search for novel analgesics that selectively target this sodium channel subunit.

Neurodegenerative disorders such as Parkinson and Alzheimer disease cause motor and cognitive dysfunction and belong to a heterogeneous group of common and disabling disorders. Although the complex molecular pathophysiology of neurodegeneration is largely unknown, major advances have been achieved by elucidating the genetic defects underlying mendelian forms of these diseases. This has led to the discovery of common pathophysiological pathways such as enhanced oxidative stress, protein misfolding and aggregation and dysfunction of the ubiquitin-proteasome system. Here, we describe loss-of-function mutations in a previously uncharacterized, predominantly neuronal P-type ATPase gene, ATP13A2, underlying an autosomal recessive form of early-onset parkinsonism with pyramidal degeneration and dementia (PARK9, Kufor-Rakeb syndrome). Whereas the wild-type protein was located in the lysosome of transiently transfected cells, the unstable truncated mutants were retained in the endoplasmic reticulum and degraded by the proteasome. Our findings link a class of proteins with unknown function and substrate specificity to the protein networks implicated in neurodegeneration and parkinsonism.

Centrioles and centrosomes have an important role in animal cell organization, but it is uncertain to what extent they are essential for animal development. The Drosophila protein DSas-4 is related to the human microcephaly protein CenpJ and the C. elegans centriolar protein Sas-4. We show that DSas-4 is essential for centriole replication in flies. DSas-4 mutants start to lose centrioles during embryonic development, and, by third-instar larval stages, no centrioles or centrosomes are detectable. Mitotic spindle assembly is slow in mutant cells, and approximately 30% of the asymmetric divisions of larval neuroblasts are abnormal. Nevertheless, mutant flies develop with near normal timing into morphologically normal adults. These flies, however, have no cilia or flagella and die shortly after birth because their sensory neurons lack cilia. Thus, centrioles are essential for the formation of centrosomes, cilia, and flagella, but, remarkably, they are not essential for most aspects of Drosophila development.

Genetic mapping studies identified ATR as a candidate gene for Seckel syndrome, but its location on the physical map had not been defined. We used the ATR cDNA sequence to identify a 112-kb genomic sequence 4 that in turn retrieved two linked BACs, one of which was located at 147.77 Mb on chromosome 3, Published online 17 March 2003, doi:10.1038/ng1129 Fig. 1 F02-98 cells show an impaired response to DNA damage. a, F02-98 cells were impaired in phosphorylation of H2AX (γH2AX) and p53 Ser15 induced by ultraviolet radiation (UV) but normal in phosphorylation of these substrates after exposure to ionizing radiation (IR). Owing to difficulty in obtaining sufficient material from primary fibroblast cells for western blotting, the phosphorylation of ATR substrates after exposure to DNAdamaging agents was examined by immunofluorescence using phosphospecific antibodies (α-P-Ser15-p53). Phosphorylation was examined after exposure to ionizing radiation (10 Gy) and ultraviolet radiation (5 J m -2 ) 1 h after irradiation. Cells held under low-serum conditions for 5 d before exposure to ultraviolet radiation had an identical response to that of exponentially growing cells (data not shown). b, F02-98 cells were impaired in phosphorylation of hRad17 and Nbs1 induced by ultraviolet radiation (UV). The examination of phosphorylation was carried out as described in a using phosphospecific antibodies (α-PRad17 and α-P-Nbs1). Immunofluorescence was also analyzed using antibodies that recognize endogenous Rad17 and Nbs1 (α-Rad17 and α-Nbs1; right panels) verifying that these proteins were expressed efficiently before and after ultraviolet radiation treatment in F02-98 cells.

BACKGROUND-Duplications and deletions in the human genome can cause disease or predispose persons to disease. Advances in technologies to detect these changes allow for the routine identification of submicroscopic imbalances in large numbers of patients.