Mutational analysis of the TSC1 and TSC2 genes in a diagnostic setting: genotype--phenotype correlations and comparison of diagnostic DNA techniques in Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterised by the development of hamartomas in multiple organs and tissues. TSC is caused by mutations in either the TSC1 or TSC2 gene. We searched for mutations in both genes in a cohort of 490 patients diagnosed with or suspected of having TSC using a combination of denaturing gradient gel electrophoresis, single-strand conformational polymorphism, direct sequencing, fluorescent in situ hybridisation and Southern blotting. We identified pathogenic mutations in 362 patients, a mutation detection rate of 74%. Of these 362 patients, 276 had a definite clinical diagnosis of TSC and in these patients 235 mutations were identified, a mutation detection rate of 85%. The ratio of TSC2:TSC1 mutations was 3.4:1. In our cohort, both TSC1 mutations and mutations in familial TSC2 cases were associated with phenotypes less severe than de novo TSC2 mutations. Interestingly, consistent with other studies, the phenotypes of the patients in which no mutation was identified were, overall, less severe than those of patients with either a known TSC1 or TSC2 mutation.     

Screening for familial ovarian cancer: failure of current protocols to detect ovarian cancer at an early stage according to the international Federation of gynecology and obstetrics system.

PURPOSE: To assess the effectiveness of annual ovarian cancer screening (transvaginal ultrasound and serum CA-125 estimation) in detecting presymptomatic ovarian cancer in women at increased genetic risk. PATIENTS AND METHODS: A cohort of 1,110 women at increased risk of ovarian cancer were screened between January 1991 and March 2004; 553 were moderate-risk individuals (4% to 10% lifetime risk) and 557 were high-risk individuals (> 10% lifetime risk). Outcome measurements include the number and stage of screen-detected cancers, the number and stage of cancers not detected at screening, the number of equivocal screening results requiring recall/repetition, and the number of women undergoing surgery for benign disease. RESULTS: Thirteen epithelial ovarian malignancies (12 invasive and one borderline), developed in the cohort. Ten tumors were detected at screening: three International Federation of Gynecology and Obstetrics (FIGO) stage I (including borderline), two stage II, four stage III, and one stage IV. Of the three cancers not detected by screening, two were stage III and one was stage IV; 29 women underwent diagnostic surgery but were found not to have ovarian cancer. CONCLUSION: Annual surveillance by transvaginal ultrasound scanning and serum CA-125 measurement in women at increased familial risk of ovarian cancer is ineffective in detecting tumors at a sufficiently early stage to influence prognosis. With a positive predictive value of 17% and a sensitivity of less than 50%, the performance of ultrasound does not satisfy the WHO screening standards. In addition, the combined protocol has a particularly high false-positive rate in premenopausal women, leading to unnecessary surgical intervention.     

Impact of patient distance to radiation therapy on mastectomy use in early-stage breast cancer patients.

PURPOSE: Treatment access underlies quality cancer care. We hypothesize that mastectomy rates in a rural state are independently influenced by distance to radiation therapy (XRT) and by changing XRT access through opening new facilities. PATIENTS AND METHODS: Early-stage breast cancer patients diagnosed from 1996 to 2000 were identified in the Virginia state registry. Distance from patient zip code to nearest XRT facility was calculated with geographical software. Distance to XRT facility (< or = 10, > 10 to 25, > 25 to 50, and > 50 miles), American Joint Committee on Cancer tumor stage, age, race, and diagnosis year were evaluated for influencing mastectomy rate. Mastectomy use within 15 miles of five new facilities was assessed before and after opening. RESULTS: Among 20,094 patients, 43% underwent mastectomy, 53% underwent lumpectomy, and therapy of 4% of patients is unknown. Twenty-nine percent of patients lived more than 10 miles from XRT facility. Mastectomy increased with distance to XRT facility (43% at < or = 10 miles, 47% at > 10 to 25 miles, 53% at > 25 to 50 miles, and 58% at > 50 miles; P < .001). Among 11,597 patients with T1 (< 2 cm) tumors, mastectomy also varied by distance (31% at < or = 10 miles, 36% at > 10 to 25 miles, 41% at > 25 to 50 miles, and 49% at > 50 miles; P < .001). In multivariate analysis, mastectomy use was independently influenced by XRT distance after adjusting for age, race, T stage, and diagnosis year. Over the study period, mastectomy rates declined from 48% to 43% across Virginia, and there were similar declines in a 15-mile area around four new radiation facilities in urban settings. However, mastectomies decreased from 61% to 45% around a new XRT facility in a rural setting. CONCLUSION: Distance to XRT facility significantly impacts mastectomy use. Opportunities for increasing breast-conservation rates through improved XRT access exist.     

Infantile and adult testicular germ cell tumors. a different pathogenesis?

Most adult testicular germ cell tumors have a characteristic chromosomal abnormality that is an isochromosome 12p [i(12p)]. Furthermore, these tumors are characterized by a chromosome number in the triploid range and gains and losses of (parts of) specific chromosomes. Cytogenetic investigation of three cases of infantile testicular germ cell tumors, all diagnosed as yolk sac tumors, revealed highly abnormal karyotypes. We found one case to be diploid; the other two cases were in the hypertriploid/hypotetraploid range. Structural abnormalities of chromosomes 1, 3, and 6 were recurrent and no i(12p) was found. Our results, together with data from the literature, suggest that infantile and adult testicular germ cell tumors have a different origin and pathogenetic pathway. Aberrations of chromosomes 1, 3, and 6 may play an important role in the pathogenesis of infantile testicular yolk sac tumors.     

Molecular genetics of Leber congenital amaurosis

Leber congenital amaurosis (LCA) is the most common inherited cause of blindness in childhood and is characterised by a severe retinal dystrophy before the age of one year. Six genes have been identified that together account for approximately half of all LCA patients. These genes are expressed preferentially in the retina or the retinal pigment epithelium. Their putative functions are quite diverse and include retinal embryonic development (CRX), photoreceptor cell structure (CRB1), phototransduction (GUCY2D), protein trafficking (AIPL1, RPGRIP1), and vitamin A metabolism (RPE65). The molecular data for CRB1 and RPE65 support previous hypotheses that LCA can represent the severe end of a spectrum of retinal dystrophies. Given the diverse mechanisms underlying the disease, future therapies of LCA may need to be tailored to certain genetically defined subgroups. Based on experimental evidence in mice and dogs, patients with disturbed retinal metabolism of vitamin A through a mutation in the RPE65 gene will likely be the first candidates for future therapeutic trials.     

A cross-linker-sensitive myeloid leukemia cell line from a 2-year-old boy with severe Fanconi anemia and biallelic FANCD1/BRCA2 mutations

Fanconi anemia (FA) is a rare autosomal recessive disorder characterized by congenital and developmental abnormalities, hypersensitivity to DNA cross-linking agents such as mitomycin C (MMC), and strong predisposition to acute myeloid leukemia (AML). In this article, we describe clinical and molecular findings in a boy with a severe FA phenotype who developed AML by the age of 2. Although he lacked a strong family history of cancer, he was subsequently shown to carry biallelic mutations in the FANCD1/BRCA2 gene. These included an IVS7 splice-site mutation, which is strongly associated with early AML in homozygous or compound heterozygous carrier status in FA-D1 patients. Myeloid leukemia cells from this patient have been maintained in culture for more than 1 year and have been designated as the SB1690CB cell line. Growth of SB1690CB is dependent on granulocyte macrophage colony stimulating factor or interleukin-3. This cell line has retained its MMC sensitivity and has undergone further spontaneous changes in the spectrum of cytogenetic aberrations compared with the primary leukemia. This is the second AML cell line derived from an FA-D1 patient and the first proof that malignant clones arising in FA patients can retain inherited MMC sensitivity. As FA-derived malignancies are normally not very responsive to treatment, this implies there are important mechanisms of acquiring correction of the cellular FA phenotype that would explain the poor chemoresponsiveness observed in FA-associated malignancies and might also play a role in the initiation and progression of cancer in the general population.     

BCL6 alternative translocation breakpoint cluster region associated with follicular lymphoma grade 3B

Translocations involving band 3q27, affecting the major breakpoint region (MBR) of BCL6, are common in diffuse large B-cell lymphomas (DLBCLs). Recent data suggest an alternative breakpoint cluster region (ABR) located between 245 and 285 kb 5' of BCL6, which might be associated with Follicular Lymphoma (FL). Ten DLBCLs and 9 FLs grade 3B with cytogenetic rearrangements at 3q27 were studied by fluorescence in situ hybridization (FISH) to discriminate between breakpoints at the ABR and MBR. Eight DLBCLs contained a breakpoint in the MBR, and 6 FL grade 3B (FL3B) cases contained a breakpoint in the ABR. No specific chromosomal partners could be identified in both groups. Previously published data have suggested that FL3B cases with 3q27 aberrations are closely related to the majority of DLBCLs of germinal center cell origin. However, our findings suggest that the mechanism of 3q27 rearrangement in FL3B cases is similar to the mechanism in follicular lymphomas grade 1,2, and 3A cases.     

Serum and BAL macrophage migration inhibitory factor levels in HIV infected Tanzanians with pulmonary tuberculosis or other lung diseases

Macrophage migration inhibitory factor (MIF) activates macrophages, promotes delayed-type hypersensitivity reaction, and regulates Th1/Th2 balance in inflammatory response. Serum MIF concentration is high in patients with pulmonary tuberculosis (PTB). Higher MIF levels are associated with high mortality. No study has addressed MIF levels and its role in PTB/HIV-co infection. We determined serum and BAL MIF levels in Tanzanian HIV-infected patients with and without PTB, and correlated the levels with 1-month outcome. We compared with serum MIF levels of HIV seronegative patients with PTB and of healthy controls. All HIV-infected patients irrespective of PTB infection had significantly higher serum MIF levels than HIV-seronegative patients with PTB, and than healthy controls. In HIV seropositive patients low serum MIF levels were associated with high 1-month mortality. In conclusion, HIV infection was associated with elevated serum MIF levels regardless of PTB. Low serum MIF levels were associated with high mortality.