We examined the adenomatous polyposis coli (APC) gene for disease-causing mutations in 51 unrelated Argentinean probands affected by familial adenomatous polyposis (FAP).Using a combination of the protein truncation test, the single strand conformation polymorphism technique, DNA sequencing and quantitative PCR analysis, we identified the specific mutation in 39 (average age: 28.4 years) of the 51 probands (detection rate: 76.47%); 13 are novel germline mutations and one is a novel sequence variant. There were 27 small deletions, four small duplications, five nonsense mutations in exon 15, three nonsense mutations in exons 6, 11, and 12, and one sequence variant in exon 3 identified in a patient bearing a truncating mutation in exon 15. The most common mutation (found in 10 cases) was at codon 1309. All patients negative for APC mutations were also negative for the MutY homolog (MYH) gene mutation, as expected because of fully penetrant FAP cases. This study enlarges the spectrum of APC gene mutations, and reinforces the concept of mutation heterogeneity. It also sheds light on correlations between the site of APC germline mutations and the clinical manifestations of FAP. Our data indicate that the genotype/phenotype correlations in Argentinean patients are similar to those observed in other populations.

Germline mutations in specific hot spot-codons of the RET proto-oncogene are associated with multiple endocrine neoplasia type 2 (MEN 2). Clinical RET gene testing has been routine for the last 10 years in some countries. In Argentina, RET testing excluding MEN 2B was always reported with a mutation at codon 634, with one exception: we described a novel mutation T > C transition at codon 630 (C630R), the family to which we extend the study in the present report. This family comprised 29 members in four generations including 6 individuals affected with medullary thyroid cancer (MTC), positive for the C630R mutation and normal adrenaline/ noradrenaline and ionized calcium/parathyroid hormone levels. Two asymptomatic mutation carriers aged 5 and 11 years underwent total thyroidectomy. The histopathologic examination showed C-cell hyperplasia and microcarcinoma foci, while preoperative basal calcitonins were normal for both. Our report emphasizes the importance of testing for non-hot spot RET mutations in apparently mutation negative MEN 2 families. Furthermore, it would appear that C630R mirrors C634R in penetrance (100% in this family) and in early age of onset of MTC, although paradoxically, no pheochromocytomas and hyperparathyroidism have developed. In addition to recommending RET testing before 5 years of age; we also can postulate that codon 630 may be the key point along the extracellular domain, important in the tissue-specific penetrance.

Background: Hereditary non-polyposis colon cancer (HNPCC) is an autosomal dominant syndrome predisposing to the early development of various cancers including those of colon, rectum, endometrium, ovarium, small bowel, stomach and urinary tract. HNPCC is caused by germline mutations in the DNA mismatch repair genes, mostly hMSH2 or hMLH1.

There are few data available about changes in thyroid hormone profiles after hormone replacement therapy (HRT). We analyzed the effect of two different oral estrogens/progestins (E/P) associations on thyroid hormones and thyroxine-binding globulin (TBG) levels in 14 postmenopausal normal women distributed at random into two groups. Both groups received daily for a year 2 mg of estradiol valeriante per os. In Group A (n = 7), estrogen was associated with norethisterone acetate. In Group B, estrogen was associated with promegestone in a similar schedule to Group A. Blood samples were withdrawn to measure estradiol (E2), thyroxine (T4), triiodothyronine (T3), free T4 (fT4), thyroid-stimulating hormone (TSH) and TBG before and after 3, 6 and 12 months of treatment. Estradiol level increased significantly in both groups, being higher in Group A than in B. Under therapy, T4 and TBG levels were increased in both groups, but within the normal range. T4 mean level increased by 34% in Group A and 20% in Group B. TBG increment was slightly significant for Group A (p < 0.02); with only a trend in Group B (p = 0.08). T3, fT4 and TSH levels did not change significantly and remained within the normal range. Oral therapy with associated E/P produces moderate increases in T4 and TBG levels. Our results suggest that in postmenopausal women on oral HRT, fT4 and TSH levels are the most useful tools to evaluate the thyroid axis status.

Sequencing an amplification product of the terminal segment of BRCA2 exon 11 showed apparent homozygosity for the 6174delT mutation in two healthy sisters. Subsequent sequencing of an alternate overlapping amplicon revealed the presence of the 5972C4T polymorphism, which is within the standard upstream amplification primer. This mismatch was responsible for the failure to amplify the normal (5972T) allele in both sisters who were heterozygous for the 6174delT mutation. Though the unexpected finding of apparent homozygosity for the 6174delT mutation prompted re-evaluation of the assay, the potential for false negative results due to masking of a mutation-bearing allele by such a circumstance should be a cautionary note for the testing and also in the interpretation of the results published under such assay conditions. European Journal of Human Genetics (2002) 10, 395 -397. doi:10.1038/sj.ejhg.5200821Keywords: BRCA2 6174delT; hereditary breast cancer; BRCA2 testing Genetic testing for germline mutation is one of the benefits of the genetic revolution of the last decade, allowing the detection of individuals at high risk for developing a disease. This information is important in the clinical management of the patient and the family in many instances. 1 -5 One of the most common approaches for the detection of a mutation in the germline is the amplification of the genomic DNA in the region flanking the site to be tested, and direct sequencing of that product. As a rule, both alleles are supposed to be amplified and analysable by sequencing or by other methods. 6,7 Using standard published primer sequences to test for the BRCA2 6174delT Ashkenazi Jewish founder mutation, 7 we studied a healthy 54-year-old woman with a family history of cancer on both the maternal and paternal sides of the pedigree (Figure 1). Initial analysis by sequencing an amplification product indicated apparent homozygosity for the 6174delT mutation (Figure 1). Her sister, 56 years old and also healthy, showed the same result. These findings were confirmed by bi-directional sequencing of the amplification products in both cases (not shown).The presence of polymorphic sites in the genome region where the amplification primers anneal might cause a base pair mismatch and, as a result, a lack of amplification of the allele carrying the polymorphism. The genomic sequences of the regions corresponding to both amplification primers contain a few polymorphic sites as follows: 5965T4C and, as mentioned, 5972C4T for TDSFB and 6283T4C and 6286G4A for CGORF-RH. Therefore we searched for the presence of these polymorphisms in the genomes of both sisters. Primers flanking the original amplified segment were designed to amplify and sequence the region where the former primers anneal. The results showed heterozygosity for the 5972C4T polymorphism and also for the BRCA2 6174delT mutation.The recognition of this technical problem is important. As was discovered here, a false report of homozygosity could be described for the mutated allele using the standard ass...