Human TUBB3 mutations perturb microtubule dynamics, kinesin interactions, and axon guidance.

We report that eight heterozygous missense mutations in TUBB3, encoding the neuron-specific beta-tubulin isotype III, result in a spectrum of human nervous system disorders that we now call the TUBB3 syndromes. Each mutation causes the ocular motility disorder CFEOM3, whereas some also result in intellectual and behavioral impairments, facial paralysis, and/or later-onset axonal sensorimotor polyneuropathy. Neuroimaging reveals a spectrum of abnormalities including hypoplasia of oculomotor nerves and dysgenesis of the corpus callosum, anterior commissure, and corticospinal tracts. A knock-in disease mouse model reveals axon guidance defects without evidence of cortical cell migration abnormalities. We show that the disease-associated mutations can impair tubulin heterodimer formation in vitro, although folded mutant heterodimers can still polymerize into microtubules. Modeling each mutation in yeast tubulin demonstrates that all alter dynamic instability whereas a subset disrupts the interaction of microtubules with kinesin motors. These findings demonstrate that normal TUBB3 is required for axon guidance and maintenance in mammals.

Heterozygous mutations of the kinesin KIF21A in congenital fibrosis of the extraocular muscles type 1 (CFEOM1).

Congenital fibrosis of the extraocular muscles type 1 (CFEOM1; OMIM #135700) is an autosomal dominant strabismus disorder associated with defects of the oculomotor nerve. We show that individuals with CFEOM1 harbor heterozygous missense mutations in a kinesin motor protein encoded by KIF21A. We identified six different mutations in 44 of 45 probands. The primary mutational hotspots are in the stalk domain, highlighting an important new role for KIF21A and its stalk in the formation of the oculomotor axis.

Utilizing Public Health Frameworks and Partnerships to Ensure Equity in DNA-Based Population Screening.

DNA-Based population screening in the United States has the promise to improve the health of all people in all communities. We highlight recent DNA-based population screening examples at the state, local, and individual level. Key public health principles and concepts with a focus on equity appear to be lacking in current efforts. We request 'A Call to Action' that involves all partners in DNA-based population screening. Potential actions to consider include: a) identification and elimination of systemic barriers that result in health inequities in DNA-based population screening and follow-up; b) creation of a national multidisciplinary advisory committee with representation from underserved communities; c) revisiting well-described public health screening principles and frameworks to guide new screening decisions and initiatives; d) inclusion of the updated Ten Essential Public Health Services with equity at the core in efforts at the local, state and national level.

Psychological impact of recall in high-risk breast MRI screening.

PURPOSE: To address the widespread concern that false-positive results during breast MRI screening may have adverse psychological effects. METHODS: Impact of Event Scale measurements in 103 high-risk women enrolled in a longitudinal MRI screening study and comparison of subjects with normal results vs. those with prior recall events. RESULTS: Of 189 MRI scans performed, 64 (34%) prompted further evaluation. Subjects with previously abnormal results had significantly higher Avoidance scores at the time of their second MRI. Multivariate analysis showed this was driven by the greater number of BRCA1/2 carriers in that group but was not related to screening recall. CONCLUSIONS: Practitioners' concerns about the high false positive rate of breast MRI may not be matched by actual psychological effects in most high-risk women.

Genetic study of familial uveal melanoma: association of uveal and cutaneous melanoma with cutaneous and ocular nevi.

PURPOSE: To evaluate a kindred with familial uveal and cutaneous melanoma and to identify potential genetic and environmental factors that may predispose individuals to develop uveal melanoma. DESIGN: Family-based case report with detailed clinical and genetic evaluation. PARTICIPANTS: Ten siblings in a single nuclear family. METHODS: Evaluation of a large sibship via family history, complete eye and skin examinations, environmental risk factor questionnaire, and genetic testing, as well as a MEDLINE search of familial uveal melanoma kindreds. MAIN OUTCOME MEASURES: Cutaneous and ocular nevi, benign and malignant neoplasms of skin and other sites, brief skin cancer risk assessment tool risk classification for cutaneous melanoma, DNA sequencing of p16INK4a and p14ARF genes, and citations on familial uveal melanoma. RESULTS: The proband and his mother had uveal melanoma, 3 cutaneous melanomas occurred among 2 siblings, and 2 other siblings had basal cell carcinomas. No germline mutations were detected in the melanoma-associated tumor suppressor genes p16INK4a and p14ARF. Seven out of 10 siblings had a history of cutaneous and/or ocular nevi. Of the 3 subjects without nevi, 2 had histories of eye or skin malignancies (1 uveal melanoma, 1 basal cell carcinoma). Three of the 10 siblings had relevant ocular findings (2 choroidal nevi, 1 uveal melanoma). Six were also found to be in the "high-risk" classification for cutaneous malignancies based on scores from a previously validated risk assessment tool. This family, combined with the 91 previously reported familial uveal melanoma kindreds, brings to 92 the total number thus far recorded. CONCLUSIONS: Our results strengthen the association between uveal melanoma, atypical nevi, and cutaneous melanoma. This relationship supports the recommendation that individuals with a personal or family history of uveal melanoma, particularly in combination with atypical nevi, should be regularly screened for uveal and cutaneous melanoma.

The I1307K APC polymorphism in Ashkenazi Jews with colorectal cancer: clinical and pathologic features.

Colorectal cancer is common in Ashkenazi Jews. The I1307K APC mutation occurs in 6-7% of Ashkenazi Jews and increases the risk of colorectal cancer. This study aimed to describe the clinical, pathologic and epidemiologic features of colorectal cancer in I1307K carriers to determine whether there were any features which might warrant individual screening for the mutation. In all, 215 Ashkenazi Jews with a personal history of colorectal cancer were enrolled. Clinical and family history, pathology reports, and slides were obtained and blood drawn for I1307K determination. The presence of the mutation was determined by PCR from white blood cell DNA. Colorectal cancer pathology slides were read in a blinded fashion. Of the 215 enrolled patients, 26 (12.1%) tested positive for I1307K. There was no difference in the pathologic features between colorectal cancers in Ashkenazi carriers compared to noncarriers. There was no difference in the age at diagnosis or history of second or other primaries. Carriers had an increased likelihood of having a first-degree relative with colorectal cancer (50%) compared to noncarriers (28%, P < 0.04). We could find no distinguishing feature other than family history that characterizes I1307K positive colorectal cancers. We could find no group of Ashkenazi Jews with colorectal cancer for whom screening for I1307K would be clinically useful.

Evaluation of laboratory perspectives on hereditary cancer panels.

Genetic counseling and testing for hereditary cancer susceptibility is a rapidly evolving field and partly a result of next-generation sequencing (NGS) allowing analysis of multiple cancer susceptibility genes simultaneously. This qualitative study explored laboratory perspectives on hereditary cancer panels. Semi-structured interviews were conducted with representatives of clinical laboratories offering hereditary cancer panels via NGS. Several themes emerged from the responses pertaining to hereditary cancer panel development, the importance of communication of panel properties with patients, variant reporting policies, and the future of hereditary cancer gene testing. Clinical utility was discussed as primary consideration during panel development. In addition, while participants indicated gene and syndrome overlap prompted panel development in general, laboratories differed in their opinions of whether phenotypic overlap warrants offering pan-cancer panels only versus cancer specific panels. Participants stressed the importance of patients understanding implications of panel testing, including what is tested for and limitations of testing. While all laboratories discussed the limitations of a variant of uncertain significance result, they differed significantly in their reporting methods. This study provides healthcare providers information on the laboratory approach to panel testing, highlighting both commonalities and differences in laboratory approaches, and may allow providers to make more informed decisions when ordering hereditary cancer panels.

Characterization and prevalence of PITX2 microdeletions and mutations in Axenfeld-Rieger malformations.

PURPOSE: Mutations of the homeodomain protein PITX2 produce Axenfeld-Rieger (AR) malformations of the anterior chamber, an autosomal dominant disorder accompanied by a 50% risk of glaucoma. Twenty-nine mutations of PITX2 have been described, with a mutational prevalence estimated between 10% and 60% in AR. In the current study, the possible role of altered PITX2 gene dosage in the etiology of AR was investigated. Gross gene deletions and duplications should alter PITX2 activity analogously to hypomorphic and hypermorphic mutations, respectively. METHODS: Sixty-four patients with AR, iridogoniodysgenesis (IGD), iris hypoplasia (IH), or anterior segment dysgenesis (ASD) were screened for PITX2 mutations by sequencing. PITX2 gene dosage was concurrently examined in these patients by real-time quantitative PCR. Microsatellite markers were used to map 4q25 microdeletions at a contig scale, as well as for haplotype analysis in an extended AR kindred. An additional 27 patients with other assorted ocular phenotypes were evaluated by similar methods, amounting to a total of 91 cases analyzed. RESULTS: Three novel mutations of PITX2 (4.7%) were identified among 64 patients with AR, IGD, IH, or ASD. Deletions of PITX2 were as frequent as mutations in our sample. Chromosome 4q25 microdeletions were physically mapped relative to several microsatellite markers in each patient. Cosegregation of AR and a PITX2 deletion was demonstrated in an extended kindred. CONCLUSIONS: Point mutations and gross deletions of PITX2 appear to produce an equivalent haploinsufficiency phenotype. Quantitative PCR is an efficient means of detecting causative PITX2 deletions in patients with AR and may increase the detection rate at this locus.

Cancer genetic testing panels for inherited cancer susceptibility: the clinical experience of a large adult genetics practice.

Next-generation sequencing genetic testing panels for cancer susceptibility (cancer panels) have recently become clinically available. At present, clinical utility is unknown and there are no set criteria or guidelines established for whom to offer such testing. Although it may be a cost-effective method to test multiple cancer susceptibility genes concurrently, the rate of finding variants of unknown significance (VUS) may be high and testing may yield mutations in genes with no established management recommendations. We describe our Center's experience over a 14-month period (April 2012-June 2013) for patient interest and uptake in cancer panel testing and whether there were predictors of pursuing testing or identifying mutations. Using a clinical ranking system, patients' family histories were ranked from 0 to 3 (low likelihood to high likelihood for underlying genetic susceptibility). The clinical ranking system was assessed to determine its predictability of finding mutations. Of the 689 patients who met inclusion criteria, the option of pursuing a cancer panel was discussed with 357 patients; 63 (17.6 %) patients pursued testing. Those who pursued testing were more likely to be older, male, affected with cancer, affected with multiple primary cancers, and had a higher clinical rank than non-pursuers. There were no significant predictors of finding a mutation on panel testing. Of the 61 patients who have received results, there was a 6.6 % mutation rate and 19.7 % VUS rate. The yield of cancer panels in clinical practice is low and the strength of family history alone may not predict likelihood of finding a mutation.

10 rare tumors that warrant a genetics referral.

The number of described cancer susceptibility syndromes continues to grow, as does our knowledge on how to manage these syndromes with the aim of early detection and cancer prevention. Oncologists now have greater responsibility to recognize patterns of cancer that warrant referral for a genetics consultation. While some patterns of common cancers are easy to recognize as related to hereditary cancer syndromes, there are a number of rare tumors that are highly associated with cancer syndromes yet are often overlooked given their infrequency. We present a review of ten rare tumors that are strongly associated with hereditary cancer predisposition syndromes: adrenocortical carcinoma, carcinoid tumors, diffuse gastric cancer, fallopian tube/primary peritoneal cancer, leiomyosarcoma, medullary thyroid cancer, paraganglioma/pheochromocytoma, renal cell carcinoma of chromophobe, hybrid oncocytoic, or oncocytoma histology, sebaceous carcinoma, and sex cord tumors with annular tubules. This review will serve as a guide for oncologists to assist in the recognition of rare tumors that warrant referral for a genetic consultation.

Genetic testing by cancer site: ovary.

Approximately 1 in every 4 to 5 women with a diagnosis of ovarian cancer has a hereditary gene mutation that is responsible for the development of her cancer. Identifying women at increased risk of developing ovarian cancer due to a hereditary cancer syndrome can allow for early detection or prevention of not only ovarian cancer, but also other cancers, depending on the causative gene. This review focuses on 3 of the most common hereditary ovarian cancer syndromes, hereditary breast and ovarian cancer syndrome (the BRCA1 and BRCA2 genes), Lynch syndrome (also known as hereditary nonpolyposis colorectal cancer syndrome), and Peutz-Jeghers syndrome, including key features, genetics, and management of these syndromes. In addition, newly discovered genes (eg, RAD51C and RAD51D) linked to ovarian cancer are discussed.