Mutations in progranulin cause tau-negative frontotemporal dementia linked to chromosome 17

Frontotemporal dementia (FTD) is the second most common cause of dementia in people under the age of 65 years. A large proportion of FTD patients (35-50%) have a family history of dementia, consistent with a strong genetic component to the disease. In 1998, mutations in the gene encoding the microtubule-associated protein tau (MAPT) were shown to cause familial FTD with parkinsonism linked to chromosome 17q21 (FTDP-17). The neuropathology of patients with defined MAPT mutations is characterized by cytoplasmic neurofibrillary inclusions composed of hyperphosphorylated tau. However, in multiple FTD families with significant evidence for linkage to the same region on chromosome 17q21 (D17S1787-D17S806), mutations in MAPT have not been found and the patients consistently lack tau-immunoreactive inclusion pathology. In contrast, these patients have ubiquitin (ub)-immunoreactive neuronal cytoplasmic inclusions and characteristic lentiform ub-immunoreactive neuronal intranuclear inclusions. Here we demonstrate that in these families, FTD is caused by mutations in progranulin (PGRN) that are likely to create null alleles. PGRN is located 1.7 Mb centromeric of MAPT on chromosome 17q21.31 and encodes a 68.5-kDa secreted growth factor involved in the regulation of multiple processes including development, wound repair and inflammation. PGRN has also been strongly linked to tumorigenesis. Moreover, PGRN expression is increased in activated microglia in many neurodegenerative diseases including Creutzfeldt-Jakob disease, motor neuron disease and Alzheimer's disease. Our results identify mutations in PGRN as a cause of neurodegenerative disease and indicate the importance of PGRN function for neuronal survival.     

Familial combined hyperlipidaemia linked to the apolipoprotein AI-CII-AIV gene cluster on chromosome 11q23-q24.

Familial combined hyperlipidaemia (FCHL) is a common inherited disorder of lipid metabolism with a prevalence of 0.5-2.0% (refs 1, 2). It is estimated to cause 10% of premature coronary heart disease. The underlying metabolic and genetic defects in FCHL have not been identified, but a population study has suggested an association between FCHL and an XmnI restriction fragment length polymorphism (RFLP) within the apolipoprotein AI-CIII-AIV gene cluster. Here we confirm this association and show that it results from linkage disequilibrium between FCHL and the 6.6-kilobase (kb) allele of the XmnI RFLP. Subsequent analysis in seven FCHL families, ascertained through a proband carrying the 6.6 kb XmnI allele, demonstrated linkage to the AI-CIII-AIV cluster on 11q23-q24, zeta = 6.86 with no recombinants. This assignment will facilitate the identification of the mutation that causes hyperlipidaemia in these families.     

人染色体17q12区雨330kb范围内表达顺序的筛选

用定位于人染色体17q12区带的长约330kbYAC克隆500D09（取自法国人类多态性研究中心YAC库）作为杂交探针，筛选人骨髓、胎脑、胎肾、骨骼肌和睾丸等五种组织的cDNA库（2×105～3×105pfu／库），从中获得102个初级阳性克隆．初级克隆经PCR扩增，分别与人基因组DNA、酵母基因组DNA和人rDNA探针作dotblot杂交分析，排除其中假阳性克隆后，复筛得到32个候选克隆．对其中2个候选克隆B4511和S5511分别测定143bp和147bp序列．经查新和同源性分析，这两个片段与已知基因的同源性均小于50％，提示它们可能是来自于新基因的表达顺序．     

No linkage of chromosome 5q11-q13 markers to schizophrenia in Scottish families

Recent work suggests that an autosomal dominant gene for schizophrenia may be located on the 5q11-q13 region of chromosome 5 (refs 1 and 2): a report of schizophrenia associated with trisomy 5q11-q13 in two members of a family of Chinese origin prompted the discovery of linkage with markers p105-599Ha and p105-153Ra in five Icelandic and two English schizophrenic families. The strongest linkage was observed when the phenotype was broadly defined to include minor psychiatric diagnoses not traditionally considered part of the schizophrenia spectrum. By contrast, no evidence was found of linkage in a single multiplex Swedish schizophrenic pedigree. To determine whether these conflicting results arise from genetic and/or uncertainties in defining the schizophrenic phenotype, we examined fifteen Scottish schizophrenic families with restriction fragment length polymorphisms that span this region. We found no evidence for linkage, regardless of how broadly or narrowly the schizophrenic phenotype is defined, and conclude that a susceptibility locus, whose presence awaits confirmation, on the proximal portion of the long arm of chromosome 5 can be responsible for only a minority of cases of familial schizophrenia.     

Type 1 diabetes in mice is linked to the interleukin-1 receptor and Lsh/Ity/Bcg genes on chromosome 1.

Human type 1 (insulin-dependent) diabetes is a common auto-immune disease of the insulin-producing beta cells of the pancreas which is caused by both genetic and environmental factors. Several features of the genetics and immunopathology of diabetes in nonobese diabetic (NOD) mice are shared with the human disease. Of the three diabetes-susceptibility genes, Idd-1 -3 and -4 that have been mapped in mice to date, only in the case of Idd-1 is there any evidence for the identity of the gene product: allelic variation within the murine immune response I-A beta gene and its human homologue HLA-DQB1 correlates with susceptibility, implying that I-A beta is a component of Idd-1. We report here the mapping of Idd-5 to the proximal region of mouse chromosome 1. This region contains at least two candidate susceptibility genes, the interleukin-1 receptor gene and Lsh/Ity/Bcg, which encodes resistance to bacterial and parasitic infections and affects the function of macrophages.