RESUMO
Germline mutations in the PTEN gene have recently been identified in some individuals with Cowden disease (CD), Lhermitte-Duclos disease (LDD), and Bannayan-Zonana syndrome. We report on a patient with CD and LDD in whom a unique de novo germline missense mutation is present in the PTEN gene. Direct sequence analysis detected a transitional change (T-->C) at nucleotide 335, resulting in substitution of the amino acid proline for leucine. The mutation is in exon 5, which has been proposed as a "hot-spot" for germline mutations. Comparison of this patient's clinical course with the previously reported cases of CD and LDD shows more extensive and more severe clinical findings than reported previously. Findings in this patient contribute to the current understanding of germline PTEN mutations and clinical outcome.
Assuntos
Neoplasias Cerebelares/genética , Ganglioneuroma/genética , Síndrome do Hamartoma Múltiplo/genética , Monoéster Fosfórico Hidrolases/genética , Proteínas Supressoras de Tumor , Adulto , Feminino , Mutação em Linhagem Germinativa , Humanos , Mutação de Sentido Incorreto , PTEN Fosfo-Hidrolase , Mutação Puntual , Dermatopatias/genética , SíndromeRESUMO
Cowden's syndrome (CS) is an autosomal dominant disorder associated with an increased risk of developing benign and malignant tumors in a variety of tissues, including the skin, thyroid, breast and brain. Women with CS are felt to have an increased risk of developing breast cancer, and virtually all women with CS develop bilateral fibrocystic disease of the breast. Recently, a series of germline mutations have been identified from CS families in a gene known as PTEN/MMAC1/TEP1. In this study, we used heteroduplex analysis and direct sequencing analysis and identified three novel germline mutations in the PTEN/MMAC1/TEP1 coding sequence from unrelated individuals with CS. We report a de novo transition (T-->C) at nucleotide 335 in exon 5. This missense mutation resulted in a leucine to proline (CTA to CCA) change at codon 112. We also describe a novel splice site mutation (801+2T-->G) in intron 7 that caused exon skipping in PTEN/MMAC1/TEP1 mRNA. The third mutation we report is a missense mutation, consisting of a transition (T-->C) at nucleotide 202 in exon 3, resulting in a tyrosine to histidine (TAC to CAC) change at codon 68. Finally, we also detected a rare polymorphism in exon 7 of the PTEN/MMAC1/TEP1 coding sequence. These data confirm the observation that mutations of the PTEN/MMAC1/TEP1 coding sequence are responsible for at least some cases of CS, and further define the spectrum of mutations in this autosomal dominant disorder.
Assuntos
Genes Supressores de Tumor , Mutação em Linhagem Germinativa/genética , Síndrome do Hamartoma Múltiplo/genética , Monoéster Fosfórico Hidrolases , Proteínas Tirosina Fosfatases/genética , Proteínas Supressoras de Tumor , Adulto , Idoso , Feminino , Humanos , PTEN Fosfo-Hidrolase , LinhagemRESUMO
Approximately 5-10% of breast and ovarian cancer cases are due to an inherited susceptibility. The majority of inherited breast and ovarian cancer susceptibility is due to mutations in the BRCA1 and BRCA2 genes; however, other genes responsible for inherited susceptibility to these diseases are yet to be identified. A small proportion of inherited breast and ovarian cancers are due to other genetic cancer susceptibility syndromes including Li-Fraumeni syndrome, Cowden disease and hereditary non-polyposis colorectal cancer. It is recommended that individuals at risk for inherited susceptibility to breast and/or ovarian cancer who are requesting DNA testing be provided with pre-test genetic counseling and education and post-test counseling and follow-up to ensure that all aspects of genetic testing have been disclosed and that the patient has truly given informed consent.