Comprehensive review of BAP1 tumor predisposition syndrome with report of two new cases.

The BRCA1-associated protein-1 (BAP1) tumor predisposition syndrome (BAP1-TPDS) is a recently identified hereditary cancer syndrome. Germline mutations in this tumor suppressor gene predispose families to the development of various malignancies. The molecular functions of the gene as well as the clinical phenotype of the syndrome are still being clarified. We sought to conduct a comprehensive review of published research into BAP1-TPDS to more thoroughly delineate the clinical implications of germline BAP1 mutations. We also report two additional families with germline BAP1 mutations. Current evidence demonstrates that germline BAP1 mutations predispose families to uveal melanoma, renal cell carcinoma, malignant mesothelioma, cutaneous melanoma, and possibly to a range of other cancers as well. Some of these cancers tend to be more aggressive, have a propensity to metastasize, and onset earlier in life in patients with BAP1 mutations as compared to non-predisposed patients with equivalent cancers. Although further research is necessary, this information can aid in the management, diagnosis, and therapy of these patients and their families, and highlights the importance of genetic counseling.

PTEN mosaicism with features of Cowden syndrome.

We present the first known case of somatic PTEN mosaicism causing features of Cowden syndrome (CS) and inheritance in the subsequent generation. A 20-year-old woman presented for genetics evaluation with multiple ganglioneuromas of the colon. On examination, she was found to have a thyroid goiter, macrocephaly, and tongue papules, all suggestive of CS. However, her reported family history was not suspicious for CS. A deleterious PTEN mutation was identified in blood lymphocytes, 966A>G, 967delA. Genetic testing was recommended for her parents. Her 48-year-old father was referred for evaluation and was found to have macrocephaly and a history of Hashimoto's thyroiditis, but no other features of CS. Site-specific genetic testing carried out on blood lymphocytes showed mosaicism for the same PTEN mutation identified in his daughter. Identifying PTEN mosaicism in the proband's father had significant implications for the risk assessment/genetic testing plan for the rest of his family. His result also provides impetus for somatic mosaicism in a parent to be considered when a de novo PTEN mutation is suspected.

Cancer family history characterization in an unselected cohort of 121 patients with uveal melanoma.

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. The extent of the contribution of familial/hereditary predisposition to the development of uveal melanoma is largely unknown. Thus we sought to ascertain the frequency of cancers in patients with UM and their family members to identify the prevalence of hereditary/familial predisposition to cancer in these patients. An unselected series of 121 patients with UM seen in a university-based tertiary referral program were consented to the study. Cancer histories (site and age of diagnosis) were obtained for all first- and second-degree relatives. Patients/families were classified as being potentially at high risk for hereditary predisposition if they met any of the following criteria: (1) Diagnosis of UM at age 30 or under, (2) Two or more cases of UM in the family, (3) UM plus at least one other primary cancer in the same patient (excluding non-melanoma skin and cervix cancers due to their strong environmental etiological link). (4) Family history meeting high risk criteria for a known hereditary cancer predisposition syndrome as defined by Hampel et al. (J Med Genet 41(2): 81-91, 2004). One patient had a family history of UM (0.8%). Ten patients (8.3%) had a personal and/or family history consistent with predisposition to a known hereditary cancer syndrome including six with possible hereditary breast, two with hereditary colon and two with hereditary melanomas. Twenty three patients (19%) had a personal history of a second cancer after exclusion of non-melanoma skin and cervical cancers. The frequency of cutaneous melanomas was significantly higher in UM patients than the general population (RR: 2.97, 95% CI: 1.00-6.94). Patients with a family history suggestive of a high risk predisposition to a known cancer syndrome had a significantly higher risk for having a second cancer than the remaining UM patients (P = 0.02). Our results indicate that the frequency of UM patients with high risk for a hereditary cancer predisposition is much higher than earlier estimates (0.6%) and that it could be as high as 11.6%. Our results suggest that cancer phenotypes in these patients are diverse and include cancers other than UM. Thus, alerting ophthalmologists to the need for expanding their cancer family history intake to include other cancers is warranted. It also suggests that patients with a hereditary predisposition to UM have a higher risk for the development of other cancers and that characterization of the germline genetic alterations in these patients is highly warranted.

Subset of individuals with autism spectrum disorders and extreme macrocephaly associated with germline PTEN tumour suppressor gene mutations.

The genetic aetiology of autism remains elusive. Occasionally, individuals with Cowden syndrome (a cancer syndrome) and other related hamartoma disorders such as Bannayan-Riley-Ruvalcaba syndrome, Proteus syndrome, and Proteus-like conditions, are characterised by germline PTEN mutations, and may have neurobehavioural features resembling autism as well as overgrowth and macrocephaly. Therefore, we undertook PTEN gene mutation analysis in 18 subjects mainly prospectively ascertained with autism spectrum disorder and macrocephaly. Of these 18 autistic subjects (13 males and five females; ages 3.1-18.4 years) with a head circumference range from 2.5 to 8.0 standard deviations above the mean, three males (17%) carried germline PTEN mutations. These three probands had previously undescribed PTEN mutations: H93R (exon 4), D252G (exon 7), and F241S (exon 7). They had the larger head circumference measurements amongst all our study subjects. The three residues altered in our patients were highly evolutionarily conserved. We suggest that PTEN gene testing be considered for patients with autistic behaviour and extreme macrocephaly. The gene findings may impact on recurrence risks as well as medical management for the patient.

Germline mutations in BMPR1A/ALK3 cause a subset of cases of juvenile polyposis syndrome and of Cowden and Bannayan-Riley-Ruvalcaba syndromes.

Juvenile polyposis syndrome (JPS) is an inherited hamartomatous-polyposis syndrome with a risk for colon cancer. JPS is a clinical diagnosis by exclusion, and, before susceptibility genes were identified, JPS could easily be confused with other inherited hamartoma syndromes, such as Bannayan-Riley-Ruvalcaba syndrome (BRRS) and Cowden syndrome (CS). Germline mutations of MADH4 (SMAD4) have been described in a variable number of probands with JPS. A series of familial and isolated European probands without MADH4 mutations were analyzed for germline mutations in BMPR1A, a member of the transforming growth-factor beta-receptor superfamily, upstream from the SMAD pathway. Overall, 10 (38%) probands were found to have germline BMPR1A mutations, 8 of which resulted in truncated receptors and 2 of which resulted in missense alterations (C124R and C376Y). Almost all available component tumors from mutation-positive cases showed loss of heterozygosity (LOH) in the BMPR1A region, whereas those from mutation-negative cases did not. One proband with CS/CS-like phenotype was also found to have a germline BMPR1A missense mutation (A338D). Thus, germline BMPR1A mutations cause a significant proportion of cases of JPS and might define a small subset of cases of CS/BRRS with specific colonic phenotype.

Attenuated familial adenomatous polyposis in a man with an interstitial deletion of chromosome arm 5q.

Familial adenomatous polyposis (FAP) is an inherited colon cancer syndrome caused by mutations in the APC gene on chromosome region 5q21. Patients typically present with several hundred to several thousand polyps throughout the colon. Benign and malignant extracolonic manifestations are often present. Attenuated FAP (AFAP) is a recognized variant of FAP in which patients present with fewer than 100 polyps and appear to have a delayed onset of the clinical manifestations of FAP. Mutations in specific regions of the APC gene are associated with AFAP. A full deletion of the APC gene region has previously been thought to be associated with typical FAP. We now report on a 39-year-old man with a cytogenetically visible interstitial 5q deletion. Fluorescent in situ hybridization analysis with two cosmid probes specific for the 5' and 3' ends of the gene indicated that the entire APC locus is deleted. The number of polyps (50-60) seen in this patient was consistent with AFAP, as was the absence of multiple congenital hypertrophy of the retinal pigment epithelium (CHRPE). This is the first reported case of AFAP associated with a germline deletion of the entire APC gene.

Hand-reduction malformations: genetic and syndromic analysis.

Sixty-one sequential patients initially referred because of hand-reduction abnormalities were retrospectively reviewed. Twenty distinct diagnoses were recognized. Particularly noteworthy was the number of instances in which standard classification schemes failed to explain fully the structural or syndromic characteristics in this group of patients. One-fourth (15 of 61) of the diagnoses were of disorders resulting from abnormalities of single genes; more than one-third (21 of 61) had multiple malformation syndromes. The importance of dysmorphologic and genetic investigation of individuals with congenital reduction malformations of the hands is evident from these data and from the cases presented.

Karsch-Neugebauer syndrome: split foot/split hand and congenital nystagmus.

A family with four members with split foot/split hand malformations and congenital nystagmus is described. The clinical characteristics in this family correspond to those seen in two other families previously reported. Taken together, these three families suggest that a single, pleiotropic dominant gene is causal. Karsch-Neugebauer syndrome is suggested as an appropriate eponymic designation for this disorder.