Cowden syndrome: report of a large family with macrocephaly and increased severity of signs in subsequent generations

Genomics of human congenital hydrocephalus

Congenital hydrocephalus (CH), characterized by enlarged brain ventricles, is considered a disease of pathological cerebrospinal fluid (CSF) accumulation and, therefore, treated largely by neurosurgical CSF diversion. The persistence of ventriculomegaly and poor neurodevelopmental outcomes in some post-surgical patients highlights our limited knowledge of disease mechanisms. Recent whole-exome sequencing (WES) studies have shown that rare, damaging de novo and inherited mutations with large effect contribute to ~ 25% of sporadic CH. Interestingly, multiple CH genes are key regulators of neural stem cell growth and differentiation and converge in human transcriptional networks and cell types pertinent to fetal neurogliogenesis. These data implicate genetic disruption of early brain development as the primary pathomechanism in a substantial minority of patients with sporadic CH, shedding new light on human brain development and the pathogenesis of hydrocephalus. These data further suggest WES as a clinical tool with potential to re-classify CH according to a molecular nomenclature of increased precision and utility for genetic counseling, outcome prognostication, and treatment stratification.

Mosaic partial deletion of the PTEN gene in a patient with Cowden syndrome

Cowden syndrome is an autosomal dominant condition caused by pathogenic mutations in the phosphatase and tensin homolog (PTEN) gene. Only a small proportion of identified pathogenic mutations have been reported to be large deletions and rearrangements. We report on a female patient with a previous history of breast ductal carcinoma in situ who presented to our institution for management of gastrointestinal hamartomatous polyposis. Although several neoplastic predisposition syndromes were considered, genetic evaluation determined that the patient met clinical diagnostic criteria for Cowden syndrome. Array-based comparative genomic hybridization was performed and revealed a mosaic partial deletion of the PTEN gene. Follow-up clinical history including bilateral thyroid nodules, dermatological findings, and a new primary "triple-negative" adenocarcinoma of the contralateral breast are discussed. We highlight the need for recognition and awareness of mosaicism as it may provide an explanation for variable phenotypic presentations and may alter the genetic counseling risk assessment of affected individuals and family members.

PTEN hamartoma tumor syndrome: clinical risk assessment and management protocol

The tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is an important phosphatase that counteracts one of the most critical cancer pathways: the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathways. Clinically, deregulation of PTEN function resulting in reduced PTEN expression and activity is implicated in human diseases. Cowden syndrome (CS) is an autosomal dominant disorder characterized by benign and malignant tumors. CS-related individual features occur commonly in the general population. Approximately 25% of patients diagnosed with CS have pathogenic germline PTEN mutations, which increase lifetime risks of breast, thyroid, uterine, renal and other cancers. PTEN testing and intensive cancer surveillance allow for early detection and treatment of these cancers for mutation positive patients and their relatives. In this review, we highlight our current knowledge of germline PTEN mutations in relation to human disease. We review current clinical diagnosis and management recommendations for PHTS including recent discoveries in understanding PTEN function regulation and how this can be exploited therapeutically.

Cowden syndrome: mucocutaneous lesions as precursors of internal malignancy

BACKGROUND

Cowden syndrome is an autosomal-dominant hereditary cancer syndrome with high variability and susceptibility. It is characterized by multiple hamartomas and neoplasms of ectodermal, endodermal and mesodermal origin affecting many organs and also by the increased risk of development of internal malignancies.

CASE REPORT

A 62-year-old woman was referred to our Maxillofacial Unit with a hamartomatous mass of the left lateral tongue which had slowly grown and was obstructing normal speech and restricting oral intake. The patient had a known history of Cowden syndrome and underwent excision of the lesion under general anaesthetic.

DISCUSSION

Orofacial mucocutaneous features are very common in multiple hamartoma and neoplasia syndrome with almost up to 90% of the patients being affected. These cutaneous and mucosal lesions, which are predominantly benign, often manifest prior to the development of the internal malignant tumours associated with the syndrome.

CONCLUSIONS

The prompt identification of Cowden syndrome's plethoric signs and symptoms can lead to appropriate surveillance and multidisciplinary management. Oral manifestations are frequent, prominent and usually precede the establishment of malignant tumours of visceral organs; hence, the maxillofacial surgeon or general dentist may have a significant role in the recognition of the disease. Overall prognosis is dependent on prevention or early treatment of internal malignancies; consequently, early diagnosis together with frequent follow-up forms the cornerstone of management.

Cognitive characteristics of PTEN hamartoma tumor syndromes

PURPOSE

We sought to characterize cognition in individuals with germline PTEN mutations (n = 23) as well as in PTEN mutation-negative individuals with classic Cowden syndrome or Bannayan-Riley-Ruvalcaba syndrome (n = 2).

METHODS

Twenty-five individuals completed a comprehensive neuropsychological evaluation. One sample t-tests and effect sizes were used to examine differences in participant test scores compared with normal controls. Composite scores were created for each patient within each of the cognitive domains assessed and classified as above average, average, or below average according to normative standards. χ(2) analyses compared these classifications to expected proportions in normal control samples.

RESULTS

The mean intelligence quotient was in the average range, and the range of intellectual functioning was very wide (from extremely low to very superior). However, in a large subset of patients, scores were lower than expected on measures of motor functioning, executive functioning, and memory recall, suggesting disruption of frontal circuits in these participants.

CONCLUSION

This is the first study to characterize cognition in individuals with PTEN mutations and associated syndromes using a comprehensive neuropsychological battery. Contrary to previous reports suggesting an association with intellectual disability, the mean intelligence quotient was average, and there was a broad range of intellectual abilities. Specific evidence of disruption of frontal circuits may have implications for treatment compliance and cancer surveillance, and further investigation is warranted.

Analysis of prevalence and degree of macrocephaly in patients with germline PTEN mutations and of brain weight in Pten knock-in murine model

PTEN Hamartoma Tumour Syndrome (PHTS) includes Cowden syndrome (CS), Bannayan-Riley-Ruvalcaba syndrome (BRRS), and other conditions resulting from germline mutation of the PTEN tumour suppressor gene. Although macrocephaly, presumably due to megencephaly, is found in both CS and BRRS, the prevalence and degree have not been formally assessed in PHTS. We evaluated head size in a prospective nested series of 181 patients found to have pathogenic germline PTEN mutations. Clinical data including occipital-frontal circumference (OFC) measurement were requested for all participants. Macrocephaly was present in 94% of 161 evaluable PHTS individuals. In patients ≤ 18 years, mean OFC was +4.89 standard deviations (SD) above the population mean with no difference between genders (P = 0.7). Among patients >18 years, average OFC was 60.0 cm in females and 62.8 cm in males (P < 0.0001). To systematically determine whether macrocephaly was due to megencephaly, we examined Pten(M3M4) missense mutant mice generated and maintained on mixed backgrounds. Mice were killed at various ages, brains were dissected out and weighed. Average brain weight for Pten(M3M4) homozygous mice (N = 15) was 1.02 g compared with 0.57 g for heterozygous mice (N = 29) and 0.49 g for wild-type littermates (N = 24) (P < 0.0001). Macrocephaly, secondary to megencephaly, is an important component of PHTS and more prevalent than previously appreciated. Patients with PHTS have increased risks for breast and thyroid cancers, and early diagnosis is key to initiating timely screening to reduce patient morbidity and mortality. Clinicians should consider germline PTEN testing at an early point in the diagnostic work-up for patients with extreme macrocephaly.

Cowden syndrome

Cowden syndrome (CS) is a rare inherited condition characterised by multiple hamartomas in a variety of tissues from all three embryonic layers. It is a cancer predisposition syndrome with an increased risk of developing malignancy in many tissues but especially breast, thyroid and endometrium. It is inherited in an autosomal dominant manner with ∼80% of patients having a germ-line mutation of the PTEN tumour suppressor gene. Presenting signs and symptoms are highly non-specific. Nevertheless clinicians should be able to recognise this syndrome so that patients may be screened for cancerous growths and afforded the opportunity to have genetic testing to assist them and their family members in making medical management decisions. We present a review of this unusual but important condition with particular emphasis on the diagnostic criteria, clinical features, genetics, management and surveillance.

Cowden syndrome: a critical review of the clinical literature

Cowden syndrome (CS) is a multi-system disease involving hamartomatous overgrowth of tissues of all three embryonic origins and increased risks for thyroid, breast and possibly other cancers. Benign breast, thyroid, uterine and skin lesions are also common. Approximately 80% of patients with CS have an identifiable germline mutation in the PTEN gene. The majority of the existing data on the frequencies of component clinical features have been obtained from compilations of case reports in the literature, many of which predate the establishment in 1996 of consensus diagnostic criteria. Many of these reports also suffer from ascertainment bias which emphasized the dermatologic features of the disease. This paper presents an overview of Cowden syndrome focusing on a critical evaluation of the major literature on the component cancers, benign features, and molecular findings in CS, noting the limitations of the published data.

Cowden syndrome: a critical review of the clinical literature

Cowden syndrome (CS) is a multi-system disease involving hamartomatous overgrowth of tissues of all three embryonic origins and increased risks for thyroid, breast and possibly other cancers. Benign breast, thyroid, uterine and skin lesions are also common. Approximately 80% of patients with CS have an identifiable germline mutation in the PTEN gene. The majority of the existing data on the frequencies of component clinical features have been obtained from compilations of case reports in the literature, many of which predate the establishment in 1996 of consensus diagnostic criteria. Many of these reports also suffer from ascertainment bias which emphasized the dermatologic features of the disease. This paper presents an overview of Cowden syndrome focusing on a critical evaluation of the major literature on the component cancers, benign features, and molecular findings in CS, noting the limitations of the published data.

Hamartomatous polyposis syndromes

Since the histologic description of the hamartomatous polyp in 1957 by Horrilleno and colleagues, descriptions have appeared of several different syndromes with the propensity to develop these polyps in the upper and lower gastrointestinal tracts. These syndromes include juvenile polyposis, Peutz-Jeghers syndrome, hereditary mixed polyposis syndrome, and the phosphatase and tensin homolog gene (PTEN) hamartoma tumor syndromes (Cowden and Bannayan-Riley-Ruvalcaba syndromes), which are autosomal-dominantly inherited, and Cronkhite-Canada syndrome, which is acquired. This article reviews the clinical aspects, the molecular pathogenesis, the affected organ systems, the risks of cancer, and the management of these hamartomatous polyposis syndromes. Although the incidence of these syndromes is low, it is important for clinicians to recognize these disorders to prevent morbidity and mortality in these patients, and to perform presymptomatic testing in patients at risk.

Cowden disease: a review

Cowden disease is a genetically inherited disorder presenting with multiple hamartomatous and neoplastic lesions in various organs and tissues. We present a review of the diagnostic criteria, clinical presentation, genetics, and management of this condition.

Case of Cowden syndrome associated with eccrine angiomatous hamartoma

Cowden syndrome, also known as multiple hamartoma syndrome is a rare autosomal dominant disorder characterized by multiple hamartomatous tumors of ectodermal, mesodermal and endodermal origin. A 47-year-old woman had a skin-colored plaque on the left foot. She had total abdominal hysterectomy due to uterine leiomyoma at the age of 35, and had modified radical mastectomy due to right breast cancer at 38. Thyroid adenoma was diagnosed at age 46. Physical examinations revealed macrocephaly, multiple papules of the buccal mucosa, skin tags of the neck and multiple keratotic papules of both hands. Multiple gastrointestinal polyps were detected on gastrofiberoscopy and colonoscopy. Histological examination of the skin lesion on the left foot showed an increased numbers of eccrine sweat glands and blood vessels, which are characteristic histological findings of eccrine angiomatous hamartoma (EAH), a rare benign tumor. We present a case of Cowden syndrome with an associated EAH, which has not been described in the English literatures.

Association between Cowden syndrome and Lhermitte-Duclos disease

BACKGROUND

The authors describe 2 cases of dysplasic gangliocytoma of the cerebellum or Lhermitte-Duclos disease revealing Cowden disease or multiple hamartoma neoplasia syndrome. Cowden disease is a rare autosomal dominant disorder, now considered as a phakomatosis. Nevertheless, relationships between both conditions still remain unclear, since Lhermitte-Duclos disease can also be sporadic.

CASE REPORTS

Two patients, 25 and 27 years old, were admitted to the emergency department for an acute intracranial hypertension. In both cases, magnetic resonance imaging (MRI) scan showed a mass in the cerebellar hemisphere. Pathological examination of surgical resection specimens concluded Lhermitte-Duclos disease. Because of the patients' previous personal and familial medical history, Cowden disease was suspected and confirmed by mutational analysis of the phosphatase and tensin homolog (PTEN) gene. In the first case, a nonsense punctual mutation in exon 8 was found. In the second one, a mutation was revealed in the exon 5, a mutational hot spot encoding the phosphatase catalytic core motif.

CONCLUSION

Lhermitte-Duclos disease and Cowden disease can be associated. Germline mutations of PTEN gene are known to be implicated in Cowden disease. This gene, located at chromosome 10q23-3, is a tumor suppressor gene that encodes a protein with phosphatase activity. To date, more than 80 mutations have been reported in Cowden disease. When the diagnosis of either one of these two disorders is established, it is imperative to search for the other one to detect early malignant lesions that occur in Cowden disease. Finally, a long-term follow up of the patient is required and a thorough familial screening is necessary.

The management of familial breast cancer

Epidemiological studies over the past several decades have consistently supported the concept that a proportion of breast cancers develop as the result of an inherited familial predisposition. However, until recently our understanding and knowledge of the underlying genetic processes involved have been limited. Current advances in molecular biology have shown that hereditary breast cancer may arise as the result of mutations of several specific gene loci including BRCA1, BRCA2, ATM gene, PTEN and p53. Several other less frequently occurring predisposition genes such as the androgen receptor gene (AR), the HNPCC genes and the oestrogen receptor gene may also be involved, but to a lesser extent. It is estimated that approximately 5-10% of all breast cancers involve one of these inherited predisposition genes, with BRCA1 and BRCA2 accounting for up to 90% of this group. Mutation analysis is complex in nature and is presently in a developmental and evolving phase, for which reason genetic testing should be offered on a selective basis and through genetic counselling clinics. This report reviews the current knowledge and roles of the various predisposition genes and discusses the management implications for both affected and nonaffected members of breast cancer families. Comprehensive and informative counselling is critical for women with an inherited predisposition to breast cancer and this has led to the evolution of familial cancer clinics involving a multi-disciplinary specialist team approach. Familial cancer clinics can provide individuals with information about their risk of developing breast cancer and offer advice regarding the various management options presently available.

Gastrointestinal polyposis in childhood: clinicopathologic and genetic features

Gastrointestinal polyps and certain extraintestinal lesions in children may herald a hereditary polyposis syndrome, with an increased risk of neoplasia and other health problems for both children and their relatives. The availability of molecular/genetic screening tests has increased early diagnosis of younger members of known polyposis families. This article reviews the gross and microscopic features of polyposis syndromes of childhood and summarizes the molecular/genetic advances in this field. Clinical management is also briefly discussed.

Mental deficiency, alterations in performance, and CNS abnormalities in overgrowth syndromes

Mental deficiency, alterations in performance, and central nervous system (CNS) abnormalities are discussed in the following overgrowth syndromes: Sotos syndrome, Weaver syndrome, Proteus syndrome, neurofibromatosis type 1, fragile X syndrome, syndromes with neonatal hypoglycemia, Simpson-Golabi-Behmel syndrome, hemihyperplasia, Sturge-Weber syndrome, Bannayan-Riley-Ruvalcaba/Cowden syndrome, macrocephaly-autism syndrome, PEHO syndrome, chromosomal syndromes, and other miscellaneous syndromes.

[Cowden's disease in an adolescent]

Cowden's disease is an autosomal dominantly inherited syndrome characterized by mucocutaneous lesions and multiple hamartomas. We report here a 12 years-old boy case with craniomegally, intestinal polyps, epilepsy and multiadenomatous goiter. All the lesions were beginnings. The predisposing genetic defect has been assignated to chromosomal 10 (PTEN-gene mutation). A long term follow-up is necessary because of the risk of malignancies.

Lhermitte-Duclos disease is a clinical manifestation of Cowden's syndrome

BACKGROUND

Lhermitte-Duclos disease (LDD) is a hamartomatous overgrowth of cerebellar ganglion cells, which replace granular cells and Purkinje cells. In recent years several cases involving the association between LDD and Cowden's syndrome (CS), an autosomal dominant condition characterized by multiple hamartomas and neoplastic lesions in skin and internal organs, have been reported.

METHODS

We reviewed the medical records and imaging studies of six patients with LDD who were treated at our institution, and we looked at other possible symptoms of CS.

RESULTS

Other clinical findings suggestive of CS were apparent in five patients: These included mucocutaneous lesions, acral keratosis, thyroid adenoma, fibrocystic disease, ovarian cyst, intestinal polyposis, and arteriovenous malformation. Only in the youngest patient, a 5-year-old boy, were no cutaneous or other signs found, despite extensive clinical and ultrasound examination.

CONCLUSION

Our observations strengthen the hypothesis that LDD is a neurological manifestation of CS. Patients with LDD should receive a thorough dermatological and systemic screening, because some of the lesions (breast, etc...) can develop into malignant tumors.

Cowden disease and Lhermitte-Duclos disease: characterization of a new phakomatosis

OBJECTIVE

Lhermitte-Duclos disease, or dysplastic gangliocytoma of the cerebellum, is an unusual hamartomatous lesion that can cause progressive mass effects in the posterior fossa. Cowden disease, or multiple hamartoma-neoplasia syndrome, is a rare autosomal dominant disorder characterized by mucocutaneous hamartomas and high incidences of systemic malignancies. We recently treated a patient with manifestations of both Lhermitte-Duclos disease and Cowden disease, and we were intrigued by the occurrence of these two rare disorders in the same patient. The purpose of the present study was to examine the nature of the association between Lhermitte-Duclos disease and Cowden disease.

METHODS

The records for all patients who had been diagnosed at our institution as having Lhermitte-Duclos disease were reviewed, to determine whether these patients also exhibited manifestations of Cowden disease. Data were obtained from multiple sources, including patient interviews, correspondence with treating physicians, and chart reviews.

RESULTS

During the past 40 years, five patients were diagnosed at Case Western Reserve University as having Lhermitte-Duclos disease. All five patients exhibited manifestations of Cowden disease. Before this review, Cowden disease had not been diagnosed for three of the patients. In our most recent case, the diagnoses of both disorders were established preoperatively. That patient was observed to have a deletion in the critical portion of Exon 5 of the PTEN gene, the gene associated with Cowden disease.

CONCLUSION

Inclusion of Lhermitte-Duclos disease in the Cowden disease spectrum suggests that Cowden disease is a true phakomatosis, with hamartomas arising from cutaneous and neural ectoderm. Recent advances in molecular genetics may help to refine the current descriptive classification of the phakomatoses. The association between Lhermitte-Duclos disease and Cowden disease has been under-recognized and under-reported. Recognition of this association has direct clinical relevance, because diligent long-term follow-up monitoring of individuals with Lhermitte-Duclos disease and Cowden disease may lead to the early detection of malignancy.

Is megalencephaly specific to autism?

Several recent reports have described the presence of increased head circumference (megalencephaly) in patients with autism. Although some studies have described reports of megalencephaly in other disorders such as schizophrenia in adults, few such studies have been performed in children and adolescents. In the present study, the authors compared 20 subjects with autism/ pervasive developmental disorder (DSM-IV; all males; mean age = 10.9 years) with 20 controls with attention deficit hyperactivity disorder (DSM-IV; all males; mean age = 11.1 years). Four subjects and five controls had evidence of megalencephaly. In addition to their core symptoms, the autistic subjects with megalencephaly were hyperactive and impulsive. These findings suggest that megalencephaly may not be specific to autism, and when present, it may index the presence of additional symptoms such as hyperactivity and impulsivity.

Transcatheter embolization of arteriovenous malformations in Cowden disease

A patient with Cowden disease and multiple arteriovenous malformations (AVMs) that resulted in high output heart failure is described. Cowden disease is a familial syndrome characterized by endodermal, mesodermal and ectodermal dysplasia causing benign and malignant tumors of the skin, breast, gastrointestinal tract, and thyroid gland. Our patient had gastrointestinal polyposis, a right renal tumor, a left lung tumor, an adenomatous goiter, and typical dermatologic findings such as facial papules, acral keratosis, gingival papillomatosis and hemangiomas. AVMs were observed in the pelvis, cervical vertebra, liver, and right supraclavicular area. Transcatheter embolization was performed 7 times for the pelvic AVMs, but the effect decreased with repetition and the patient died of heart failure 2 years after the first embolization. The serum levels of tissue plasminogen activator (t-PA), platelet-derived growth factor (PDGF), hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF), and transforming growth factor beta1 were high, suggesting that these angiogenic molecules may play a role in the pathogenesis of AVMs in Cowden disease.

The genetic basis of breast cancer and its clinical implications

While it has long been recognized that a proportion of breast cancer cases are the result of an inherited familial predisposition, precise knowledge of the underlying genetic processes has been lacking. Recent advances in molecular biology, however, have shown that hereditary breast cancer may eventuate as a result of mutations on several specific gene loci including BRCA1, BRCA2, ATM gene, PTEN and p53. Several other less frequently occurring predisposition genes such as the androgen receptor gene (AR), the HNPCC genes and the oestrogen receptor gene may also be involved, but to a lesser extent. Overall, approximately 5-10% of all breast cancers are thought to involve one of these inherited predisposition genes, with BRCA1 and BRCA2 being responsible for as much as 90% of this group. Because of the complex nature of genetic testing, mutation analysis is not presently routinely available outside genetic counselling clinics. In this review the current knowledge and role of each predisposition gene is outlined and the management implications of genetic testing for members of breast cancer families for both affected and non-affected members are discussed. The need to provide comprehensive counselling for women with an inherited predisposition to breast cancer has seen the evolution of the familial cancer clinic, involving a multidisciplinary specialist team approach. Familial cancer clinics will provide individuals with information about their risk of developing breast cancer and offer advice regarding further management strategies. It is important that surgeons, who have traditionally played a key role in breast cancer treatment, remain cognizant of these advances in genetic molecular biology, and in so doing continue to remain key participants in the conduct of breast cancer management.

Mapping and characterization of novel (CAG)n repeat cDNAs from adult human brain derived by the oligo capture method

The expansion of a (CAG)n trinucleotide repeat has been associated with at least eight neurological disorders in which the repeats code for polyglutamine in the protein. To identify additional genes that possess (CAG)n repeats, single-stranded cDNA clones derived from adult human brain were screened using biotinylated oligonucleotide (CAG)8, and the hybridizing complexes were isolated with strepavidin-coated paramagnetic beads. A total of 119 cDNA clones were isolated and initially characterized by end sequencing. BLAST homology searches were used to reduce redundancies with overlapping clones and to eliminate those that show sequence identity with previously published cDNAs with triplet repeats. Only cDNA clones with more than five CAG repeats were pursued for analysis. A total of 19 novel cDNAs were further characterized by determining chromosomal assignments using the Stanford G3 and Genebridge radiation-reduced hybrid mapping panels. Transcript sizes and tissue expression patterns were determined by Northern blot analysis. Two of 19 clones showed specific or high expression in brain. These cDNAs are ideal candidate genes for other neurodegenerative disorders, such as spinocerebellar ataxia types 5 and 7, and may also be implicated in psychiatric diseases such as bipolar affected disorder and schizophrenia.

Neurodevelopmental dysfunction among nonreferred children with idiopathic megalencephaly

PURPOSE

To determine whether nonreferred children with idiopathic megalencephaly show evidence of specific neurodevelopmental dysfunction compared with sibling control subjects and age-matched control subjects.

DESIGN

Cross-sectional, case-control study in a large, suburban pediatric practice. Subjects included 20 children between the ages of 6 and 15 years with a head circumference at greater than the 98th percentile, 19 siblings of these children with normalsize heads, and 16 age-matched control subjects. Standardized tests of language, academic achievement, visuomotor integration, motor function, and neurodevelopmental function were administered.

RESULTS

Multivariate analysis, with control for age, showed a main effect for the presence of megalencephaly (F = 3.2; p < 0.05). Follow-up univariate analyses, with control for age, showed that children with megalencephaly had poorer performance on tasks of upper limb speed, visuomotor control, running speed, bilateral coordination, visuomotor integration, naming fluency, and minor neurologic indicators.

CONCLUSION

The relationship between idiopathic megalencephaly and external hydrocephalus in infants is discussed. Results show that so-called "benign" idiopathic megalencephaly in nonreferred school-age children appears to be a clinical entity associated with subtle motor problems and neurodevelopmental dysfunction.

Inherited breast cancer

Five to ten percent of breast cancer is attributable to the autosomal dominant inheritance of a high-risk susceptibility gene. There are a number of known inherited cancer syndromes that confer a higher risk of breast cancer. Recently, the BRCA1 gene, which is responsible for 45% of hereditary early-onset breast cancer and for the majority of co-inheritance of breast and ovarian cancer, has been cloned. Another gene that confers an increased risk of breast cancer is the BRCA2 gene, which maps to the long arm of chromosome 13 by linkage analysis. Mutations in BRCA2 account for approximately 40% of hereditary early-onset breast cancer. In addition, at least 7% of breast cancer may occur in women who are heterozygous for mutations in a gene for ataxia-telangiectasia, an autosomal recessive chromosome instability syndrome. Predictive testing for some predisposing conditions is possible through indirect or direct mutation testing. In this article, the genetics of breast cancer are reviewed, and practical concerns for the surgeon in counseling high-risk patients are addressed.

Hereditary tumor syndromes of the nervous system: overview and rare syndromes

Hereditary tumor syndromes of the nervous system are a varied group of conditions that include neurofibromatosis 1, neurofibromatosis 2, tuberous sclerosis, and von Hippel-Lindau disease, as well as the retinoblastoma susceptibility, Li-Fraumeni, familial glioma, Turcot, Gorlin, Cowden and multiple endocrine neoplasia syndromes. For many of these conditions, the responsible genes have been localized or identified. Such studies have elucidated the genetic basis of both hereditary cancer predisposition and sporadic nervous system tumors. The first four hereditary tumors syndromes have been extensively studied and are discussed in detail in the four subsequent articles. The other syndromes have also been subject to both pathological and molecular genetic inquiries. In this introductory overview, we discuss the features common to the hereditary tumor syndromes of the nervous system, and review some of the rarer conditions.

Cowden syndrome

Cowden syndrome, or the multiple hamartoma syndrome, is a familial cancer syndrome with involvement of various organ systems. Inheritance is autosomal dominant with variable expression. Progressive macrocephaly, scrotal tongue, and mild to moderate mental retardation are important signs indicating the syndrome in young children. Other mucocutaneous symptoms, for example, trichilemmomas in the nasolabial folds and palmar and plantar hyperkeratotic pits, usually become evident later in childhood. They are often accompanied by the appearance of subcutaneous lipomas and cutaneous haemangiomas.