Worldwide distribution of PSEN1 Met146Leu mutation: a large variability for a founder mutation.

OBJECTIVE: Large kindreds segregating familial Alzheimer disease (FAD) offer the opportunity of studying clinical variability as observed for presenilin 1 (PSEN1) mutations. Two early-onset FAD (EOFAD) Calabrian families with PSEN1 Met146Leu (ATG/CTG) mutation constitute a unique population descending from a remote common ancestor. Recently, several other EOFAD families with the same mutation have been described worldwide. METHODS: We searched for a common founder of the PSEN1 Met146Leu mutation in families with different geographic origins by genealogic and molecular analyses. We also investigated the phenotypic variability at onset in a group of 50 patients (mean age at onset 40.0 +/- 4.8 years) by clinical, neuropsychological, and molecular methodologies. RESULTS: EOFAD Met146Leu families from around the world resulted to be related and constitute a single kindred originating from Southern Italy before the 17th century. Phenotypic variability at onset is broad: 4 different clinical presentations may be recognized, 2 classic for AD (memory deficits and spatial and temporal disorientation), whereas the others are expressions of frontal impairment. The apathetic and dysexecutive subgroups could be related to orbital-medial prefrontal cortex and dorsolateral prefrontal cortex dysfunction. CONCLUSIONS: Genealogic and molecular findings provided evidence that the PSEN1 Met146Leu families from around the world analyzed in this study are related and represent a single kindred originating from Southern Italy. The marked phenotypic variability might reflect early involvement by the pathologic process of different cortical areas. Although the clinical phenotype is quite variable, the neuropathologic and biochemical characteristics of the lesions account for neurodegenerative processes unmistakably of Alzheimer nature.

Heterogeneity within a large kindred with frontotemporal dementia: a novel progranulin mutation.

BACKGROUND: Frontotemporal dementia (FTD) in several 17q21-linked families was recently explained by truncating mutations in the progranulin gene (GRN). OBJECTIVE: To determine the frequency of GRN mutations in a cohort of Caucasian patients with FTD without mutations in known FTD genes. METHODS: GRN was sequenced in a series of 78 independent FTD patients including 23 familial subjects. A different Calabrian dataset (109 normal control subjects and 96 FTD patients) was used to establish the frequency of the GRN mutation. RESULTS: A novel truncating GRN mutation (c.1145insA) was detected in a proband of an extended consanguineous Calabrian kindred. Segregation analysis of 70 family members revealed 19 heterozygous mutation carriers including 9 patients affected by FTD. The absence of homozygous carriers in a highly consanguineous kindred may indicate that the loss of both GRN alleles might lead to embryonic lethality. An extremely variable age at onset in the mutation carriers (more than five decades apart) is not explained by APOE genotypes or the H1/H2 MAPT haplotypes. Intriguingly, the mutation was excluded in four FTD patients belonging to branches with an autosomal dominant mode of inheritance of FTD, suggesting that another novel FTD gene accounts for the disease in the phenocopies. It is difficult to clinically distinguish phenocopies from GRN mutation carriers, except that language in mutation carriers was more severely compromised. CONCLUSION: The current results imply further genetic heterogeneity of frontotemporal dementia, as we detected only one GRN-linked family (about 1%). The value of discovering large kindred includes the possibility of a longitudinal study of GRN mutation carriers.

The effects of APOE and tau gene variability on risk of frontotemporal dementia.

Frontotemporal dementia (FTD) is a complex dementing syndrome whose genetic/non genetic risk factors are mostly unknown. Aim of the present work was to investigate whether APOE and/or tau gene variability does affect the risk of FTD. A sample of FTD cases (sporadic: n = 54; familial: n = 46, one subject per family) was collected in a genetically homogeneous population (Calabria, southern Italy) and analyzed in comparison with an age- and sex-matched control group (n = 180) extracted from the same population. Logistic regression analysis showed that APOE gene variability affects the probability of disease, with allele epsilon4 increasing (exp(beta1) = 2.68 with [1.51-4.76] 95% confidence interval; p = 0.001) and allele epsilon2 decreasing (exp(beta1) = 0.28 with [0.12-0.66] 95% confidence interval; p = 0.003) the risk of FTD. On the contrary, tau gene variability was ineffectual (exp(beta1) non significantly different from 1 for either H1 or H2 haplotypes), although a small effect was observed by the H1 haplotype in increasing the protective effect of the epsilon2 allele (p = 0.007).

A family with Alzheimer disease and strokes associated with A713T mutation of the APP gene.

Three members of an Italian family with autosomal dominant dementia and multiple strokes had the A713T mutation of the APP gene. The neuropathologic examination of the proband disclosed Alzheimer disease (AD) with severe cerebral amyloid angiopathy and multiple infarcts. This indicates that the A713T mutation of the APP gene, lying at the gamma-secretase cleavage site, can be responsible for AD with symptomatic cerebral amyloid angiopathy.

The parkin gene is not a major susceptibility locus for typical late-onset Parkinson's disease.

We investigated the parkin gene in 118 patients with typical Parkinson's disease (PD), i.e. in patients who had an onset of PD after the age of 45 years. The study group included 95 subjects with sporadic PD and 23 subjects from 18 families with autosomal recessive PD. No pathogenetic mutations in the parkin gene were detected either in familial or in sporadic patients. Our findings indicate that the parkin gene is not involved in the pathogenesis of classic late-onset PD.

The parkin gene is not involved in late-onset Parkinson's disease.

Mutations in the parkin gene have been reported in patients with early onset PD. The authors investigated the parkin gene in 118 patients who had an onset of PD after age 45 years: 95 subjects were sporadic patients and 23 subjects were from 18 families with a probable autosomal recessive inheritance. No pathogenetic mutations in the parkin gene were detected either in familial or in sporadic patients. Moreover, no differences were found between patients and 100 age-matched normal controls in the allele and genotype frequencies of four exonic parkin polymorphisms.

A procedure for cloning genomic DNA fragments with increasing thermoresistance.

Genomic DNAs have been cleaved by restriction or sonication, and the resulting double-stranded fragments have been exposed to increasing temperatures. This treatment may induce the helix-coil transition either in a single or in several steps, depending on the size and composition of the duplexes. Eventually, a critical temperature is reached at which each duplex melts completely and the two constitutive single strands separate. A transition interval can thus be defined for each duplex by the temperature at which the earliest strand separation takes place and that at which the most resistant double-stranded core collapses. If solutions containing a mixture of DNA duplexes are exposed to temperatures within their transition intervals, three kinds of molecules should originate: (1) duplexes that have not yet initiated the melting phase; (2) duplexes that have undergone only partial melting; and (3) single strands that derive from fully melted duplexes. If the heated solutions are quickly cooled to 0 degreesC, only the molecules from the first two classes can be ligated to a compatibly ended vector and cloned: class (1) are intact duplexes, and class (2) are molecules that snap immediately back to fully duplex structures: both are double-stranded. Conversely, the single strands of class (3) may not reanneal and thus be neither ligated nor cloned. We have tested the procedure on restricted coliphage lambda DNA, in view of its compartmentalized organization and known sequence. Then, we have applied it to human genomic DNA fragmented by sonication. After cloning of the available duplexes in a bacterial plasmid, libraries of molecules endowed with a progressively higher thermoresistance can be prepared for thermodynamic and genomic studies.

Dose escalation combination carboplatin/cyclophosphamide chemotherapy for epithelial ovarian cancer.

Dose intensification chemotherapy is currently under investigation in ovarian cancer. In order to establish an optimum dose for future colony stimulating factor trials, 16 patients with ovarian cancer were treated with dose-escalation combination carboplatin plus cyclophosphamide chemotherapy without growth factors. The initial carboplatin dose, 300 mg/m2, was increased to a maximum dose of 400 mg/m2. The initial cyclophosphamide dose, 600 mg/m2, was increased to a maximum dose of 1200 mg/m2. Of 10 patients completing 6 cycles, six patients (60%) were escalated to carboplatin 400 mg/m2 and cyclophosphamide 600-1200 mg/m2. Myelosuppression was severe, with all 6 patients requiring platelet and/or packed red blood cell transfusions. Based on these results, carboplatin 400 mg/m2 with cyclophosphamide 600 mg/m2 was selected as the starting dose with hematopoietic growth factors.

Concomitant cisplatin and radiotherapy in locally advanced cervical carcinoma.

Patients with locally advanced cervical cancer have a poor prognosis. The efficacy of radiotherapy is limited by the presence of large tumor volume and nodal disease. As cisplatin is a documented radiosensitizer and has activity in squamous cell carcinomas, a prospective study was designed to evaluate the toxicity and potential synergism of concurrent cisplatin (20 mg/m2 x 5 d every 21 days) and radiotherapy in locally advanced cervical cancer. Forty-three patients were studied, of which 14 were stage IB/IIA (bulky disease) and 29 were stage IIB/IIIB/IVA. Of the 32 evaluable patients, there were 29 complete responders. Of these 29 patients, 27 remain without evidence of disease, with a median follow-up of 12 months. There were no treatment-related deaths. Cisplatin and radiotherapy appear to be a well-tolerated and highly effective regimen for locally advanced cervical cancer.