The proband should first be identified as being either an affected or unaffected individual. The past medical history should be as complete as possible, giving specific reference to known preneoplastic lesions such as benign thyroid disease, goiter, adenomatous bowel polyps, and dysplastic nevi. Specific associated clinical features of cancer syndromes should be sought in either the probands, or in the cancers of the relatives. Such features might include, for example, a history of multinodular goiter, colonic polyps, epidermoid cysts, in a family segregating FAP-associated NMTC, or trichilemmomas and macrocephaly suggestive of Cowden syndrome. A personal or familial history of developmental delay might further indicate Cowden syndrome, as might a history of hamartomatous polyps or breast fibroadenomas, or uterine leiomyomas. Alternatively, a history of supernumerary or impacted teeth might indicate an underlying diagnosis of FAP, as might a history of duodenal or gastric polyps. A history of polypectomy should be investigated further by requesting histological reports, in order to assess presence of adenomatous lesions. It is, however, more likely than not, given the rarity of FAP and Cowden syndrome, that for the majority of probands presenting with an increased risk of the common cancers a previous medical history will be unremarkable.
A history of exposure to environmental risk factors should be sought. In individuals previously treated for cancer, previous treatments should be documented in order to be able to accurately assess secondary cancer risk. Previous and current levels of tobacco smoking and alcohol consumption should be clearly docu mented. Individuals should be questioned on symptoms indicative of cancer or underlying congenital abnormalities.
The ethnic background of all probands should also be sought, given the increased probability of deleterious alleles in individuals from particular backgrounds. For example, the I1307K allele of APC is primarily restricted to individuals of Jewish ancestry . Similarly a history of consanguinity, which may be commonplace in some cultures , and associated with a higher than expected risk of disease, should be sought.
The type and scope of a physical examination when conducted within a genetic counseling session will entirely depend on the background of the counselor. Examination should be performed to detect an underlying malignancy or
Unspecified sex (number of individuals)
Arrow indicates proband
Figure 22.1 Symbols used for pedigree construction.
clinical features that might suggest an inherited predisposition syndrome. For example, the skin should be fully examined in order to exclude Cowden syndrome (verrucous skin lesions of the face and limbs, lipomas, hemangiomas, and cobblestone-like hyperkeratotic papules of the gingiva and buccal mucosa) and FAP (sebaceous or epidermoid cysts). Macrocephaly (>97th percentile) should be excluded. The body should be examined for presence of desmoids,particularly the abdomen, and also for osteomas, particularly at the mandible. Primary as well as associated malignant neoplasia should be excluded. Thus, examination of the thyroid gland should be performed in order to exclude primary malignant disease, but also benign disease (e.g. multinodular goiter). Breast examination (for malignant disease and giant breast fibroadeno-mas in the case of Cowden syndrome) is therefore warranted. Retinal examination (for retinal gliomas in the case of Cowden syndrome, and congenital hypertrophy of the retinal pigment epithelium in the case of FAP) should also be performed.
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