Donald W. Hadley

Gentamicin treatment of Duchenne and Becker muscular dystrophy due to nonsense mutations.

Aminoglycosides have previously been shown to suppress nonsense mutations, allowing translation of full‐length proteins in vitro and in animal models. In the mdx mouse, where muscular dystrophy is due to a nonsense mutation in the dystrophin gene, gentamicin suppressed truncation of the protein and ameliorated the phenotype. A subset of patients with Duchenne and Becker muscular dystrophy similarly possess a nonsense mutation, causing premature termination of dystrophin translation. Four such patients, with various stop codon sequences, were treated once daily with intravenous gentamicin at 7.5 mg/kg/day for 2 weeks. No ototoxicity or nephrotoxicity was detected. Full‐length dystrophin was not detected in pre‐ and post‐treatment muscle biopsies.

Oculofaciocardiodental and Lenz microphthalmia syndromes result from distinct classes of mutations in BCOR.

Lenz microphthalmia is inherited in an X-linked recessive pattern and comprises microphthalmia, mental retardation, and skeletal and other anomalies. Two loci associated with this syndrome, MAA (microphthalmia with associated anomalies) and MAA2, are situated respectively at Xq27–q28 (refs. 1,2) and Xp11.4–p21.2 (ref. 3). We identified a substitution, nt 254C→T; P85L, in BCOR (encoding BCL-6-interacting corepressor, BCOR) in affected males from the family with Lenz syndrome previously used to identify the MAA2 locus. Oculofaciocardiodental syndrome (OFCD; OMIM 300166) is inherited in an X-linked dominant pattern with presumed male lethality and comprises microphthalmia, congenital cataracts, radiculomegaly, and cardiac and digital abnormalities. Given their phenotypic overlap, we proposed that OFCD and MAA2-associated Lenz microphthalmia were allelic, and we found different frameshift, deletion and nonsense mutations in BCOR in seven families affected with OFCD. Like wild-type BCOR, BCOR P85L and an OFCD-mutant form of BCOR can interact with BCL-6 and efficiently repress transcription. This indicates that these syndromes are likely to result from defects in alternative functions of BCOR, such as interactions with transcriptional partners other than BCL-6. We cloned the zebrafish (Danio rerio) ortholog of BCOR and found that knock-down of this ortholog caused developmental perturbations of the eye, skeleton and central nervous system consistent with the human syndromes, confirming that BCOR is a key transcriptional regulator during early embryogenesis.

Colon Cancer Screening Practices After Genetic Counseling and Testing for Hereditary Nonpolyposis Colorectal Cancer

PURPOSE Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common hereditary form of colon cancer. Cancer screening recommendations differ between individuals identified to carry an HNPCC mutation and those who do not carry a known family mutation. We assessed the impact of genetic counseling and testing (GCT) on the use of endoscopic screening procedures and adherence to recommended endoscopic screening guidelines in 56 asymptomatic at-risk individuals from families known to carry an HNPCC mutation. PATIENTS AND METHODS We analyzed data on colonoscopy and flexible sigmoidoscopy screenings collected before GCT and 6 months and 12 months post-GCT on 17 mutation-positive and 39 true mutation-negative individuals. Main outcome measures were use of endoscopic screening and adherence to recommended guidelines for the relevant mutation status. Mutation status, age, sex, employment, and income were analyzed as predictor variables. RESULTS Among mutation-negative individuals, use of colonoscopy and flexible sigmoidoscopy decreased significantly between pre- and post-GCT (P <.00001 and P <.0003, respectively). Among mutation-positive individuals, a nonsignificant increase (P =.24) in use was noted. Age was also associated with use of endoscopic screening after GCT (P =.03). Mutation status (odds ratio [OR], 7.5; P =.02) and employment (OR, 8.6; P =.025) were associated with nonadherence to endoscopic screening guidelines. More mutation-negative individuals strictly adhered to guidelines than did mutation-positive individuals (87% v 65%). CONCLUSION Genetic counseling and testing for HNPCC significantly influences the use of colonic endoscopy and adherence to recommendations for colon cancer screening.

Psychosocial factors predicting BRCA1/BRCA2 testing decisions in members of hereditary breast and ovarian cancer families.

Although BRCA1/2 testing has increasingly entered clinical practice, much is to be learned about the most effective ways to provide counseling to persons potentially interested in receiving test results. The purpose of this study was to identify factors affecting genetic testing decisions in a cohort of hereditary breast and ovarian cancer (HBOC) families presented with the choice to undergo testing. Relatives in these families are known to carry BRCA1 or BRCA2 mutations. Sociodemographics, personality traits, and family functioning were self-assessed using validated psychometric instruments at baseline. Among 172 individuals who participated in pretest education and counseling, 135 (78%) chose to undergo genetic testing and 37 (22%) chose not to be tested. Individuals who chose to undergo genetic testing were more likely to be older (> or =40 years), to have lower levels of optimism, and to report higher levels of cohesiveness in their families. A better understanding of factors that influence interest in predictive testing may help to inform the counseling that occurs prior to genetic testing.

Communicating Genetic and Genomic Information: Health Literacy and Numeracy Considerations

Genomic research is transforming our understanding of the role of genes in health and disease. These advances, and their application to common diseases that affect large segments of the general population, suggest that researchers and practitioners in public health genomics will increasingly be called upon to translate genomic information to individuals with varying levels of health literacy and numeracy. This paper discusses the current state of research regarding public understanding of genetics and genomics, the influence of health literacy and numeracy on genetic communication, and behavioral responses to genetic and genomic information. The existing research suggests that members of the general public have some familiarity with genetic and genomic terms but have gaps in understanding of underlying concepts. Findings from the limited research base to date indicate that health literacy affects understanding of print and oral communications about genetic and genomic information. Numeracy is also likely to be an important predictor of being able to understand and apply this information, although little research has been conducted in this area to date. In addition, although some research has examined behavior change in response to the receipt of information about genetic risk for familial disorders and genomic susceptibility to common, complex diseases, the effects of health literacy and numeracy on these responses have not been examined. Potential areas in which additional research is needed are identified and practical suggestions for presenting numeric risk information are outlined. Public health genomics researchers and practitioners are uniquely positioned to engage in research that explores how different audiences react to and use genomic risk information.

Muenke syndrome (FGFR3-related craniosynostosis): expansion of the phenotype and review of the literature.

Muenke syndrome is an autosomal dominant disorder characterized by coronal suture craniosynostosis, hearing loss, developmental delay, carpal and tarsal fusions, and the presence of the Pro250Arg mutation in the FGFR3 gene. Reduced penetrance and variable expressivity contribute to the wide spectrum of clinical findings in Muenke syndrome. To better define the clinical features of this syndrome, we initiated a study of the natural history of Muenke syndrome. To date, we have conducted a standardized evaluation of nine patients with a confirmed Pro250Arg mutation in FGFR3. We reviewed audiograms from an additional 13 patients with Muenke syndrome. A majority of the patients (95%) demonstrated a mild‐to‐moderate, low frequency sensorineural hearing loss. This pattern of hearing loss was not previously recognized as characteristic of Muenke syndrome. We also report on feeding and swallowing difficulties in children with Muenke syndrome. Combining 312 reported cases of Muenke syndrome with data from the nine NIH patients, we found that females with the Pro250Arg mutation were significantly more likely to be reported with craniosynostosis than males (P < 0.01). Based on our findings, we propose that the clinical management should include audiometric and developmental assessment in addition to standard clinical care and appropriate genetic counseling. Published 2007 Wiley‐Liss, Inc.

Clinical Spectrum of SIX3-Associated Mutations in Holoprosencephaly: Correlation between Genotype, Phenotype, and Function.

Background: Holoprosencephaly (HPE) is the most common structural malformation of the human forebrain. There are several important HPE mutational target genes, including the transcription factor SIX3, which encodes an early regulator of Shh, Wnt, Bmp and Nodal signalling expressed in the developing forebrain and eyes of all vertebrates. Objective: To characterise genetic and clinical findings in patients with SIX3 mutations. Methods: Patients with HPE and their family members were tested for mutations in HPE-associated genes and the genetic and clinical findings, including those for additional cases found in the literature, were analysed. The results were correlated with a mutation-specific functional assay in zebrafish. Results: In a cohort of patients (n = 800) with HPE, SIX3 mutations were found in 4.7% of probands and additional cases were found through testing of relatives. In total, 138 cases of HPE were identified, 59 of whom had not previously been clinically presented. Mutations in SIX3 result in more severe HPE than in other cases of non-chromosomal, non-syndromic HPE. An over-representation of severe HPE was found in patients whose mutations confer greater loss of function, as measured by the functional zebrafish assay. The gender ratio in this combined set of patients was 1.5:1 (F:M) and maternal inheritance was almost twice as common as paternal. About 14% of SIX3 mutations in probands occur de novo. There is a wide intrafamilial clinical range of features and classical penetrance is estimated to be at least 62%. Conclusions: Our data suggest that SIX3 mutations result in relatively severe HPE and that there is a genotype–phenotype correlation, as shown by functional studies using animal models.

Compound Heterozygosity for Mutations in PAX6 in a Patient With Complex Brain Anomaly, Neonatal Diabetes Mellitus, and Microophthalmia

We report on a patient with trisomy 21, microophthalmia, neonatal diabetes mellitus, hypopituitarism, and a complex structural brain anomaly who was a member of a large bilineal family with eye anomalies. The patient inherited a different mutation in PAX6 from each parent and is the only known living and second reported patient with compound heterozygosity for mutations in PAX6. PAX6 is a transcription factor involved in eye and brain development and has roles in pancreatic and pituitary development. Clinical evaluation of the propositus and his parents demonstrated the effects of mutations of differing severity in multiple individuals. Published 2009 Wiley‐Liss, Inc.

Mutations in ZIC2 in Human Holoprosencephaly: Description of a Novel ZIC2-Specific Phenotype and Comprehensive Analysis of 157 Individuals

Background Holoprosencephaly (HPE), the most common malformation of the human forebrain, may be due to mutations in genes associated with non-syndromic HPE. Mutations in ZIC2, located on chromosome 13q32, are a common cause of non-syndromic, non-chromosomal HPE. Objective To characterise genetic and clinical findings in patients with ZIC2 mutations. Methods Through the National Institutes of Health and collaborating centres, DNA from approximately 1200 individuals with HPE spectrum disorders was analysed for sequence variations in ZIC2. Clinical details were examined and all other known cases of mutations in ZIC2 were included through a literature search. Results By direct sequencing of DNA samples of an unselected group of unrelated patients with HPE in our NIH laboratory, ZIC2 mutations were found in 8.4% (49/582) of probands. A total of 157 individuals from 119 unrelated kindreds are described, including 141 patients with intragenic sequence determined mutations in ZIC2. Only 39/157 patients have previously been clinically described. Unlike HPE due to mutations in other genes, most mutations occur de novo and the distribution of HPE types differs significantly from that of non-ZIC2 related HPE. Evidence is presented for the presence of a novel facial phenotype which includes bitemporal narrowing, upslanting palpebral fissures, a short nose with anteverted nares, a broad and well demarcated philtrum, and large ears. Conclusions HPE due to ZIC2 mutations is distinct from that due to mutations in other genes. This may shed light on the mechanisms involved in formation of the forebrain and face and will help direct genetic counselling and diagnostic strategies.

Monitoring coping style moderates emotional reactions to genetic testing for hereditary nonpolyposis colorectal cancer: a longitudinal study†

Objectives: The emotional effects of genetic testing for hereditary nonpolyposis colorectal cancer (HNPCC) provided within a counseling program were assessed among 253 individuals.