A review of structural brain abnormalities in Pallister-Killian syndrome.

BACKGROUND: Pallister-Killian syndrome (PKS) is a rare multisystem developmental syndrome usually caused by mosaic tetrasomy of chromosome 12p that is known to be associated with neurological defects. METHODS: We describe two patients with PKS, one of whom has bilateral perisylvian polymicrogyria (PMG), the other with macrocephaly, enlarged lateral ventricles and hypogenesis of the corpus callosum. We have also summarized the current literature describing brain abnormalities in PKS. RESULTS: We reviewed available cases with intracranial scans (n = 93) and found a strong association between PKS and structural brain abnormalities (77.41%; 72/93). Notably, ventricular abnormalities (45.83%; 33/72), abnormalities of the corpus callosum (25.00%; 18/72) and cerebral atrophy (29.17%; 21/72) were the most frequently reported, while macrocephaly (12.5%; 9/72) and PMG (4.17%; 3/72) were less frequent. To further understand how 12p genes might be relevant to brain development, we identified 63 genes which are enriched in the nervous system. These genes display distinct temporal as well as region-specific expression in the brain, suggesting specific roles in neurodevelopment and disease. Finally, we utilized these data to define minimal critical regions on 12p and their constituent genes associated with atrophy, abnormalities of the corpus callosum, and macrocephaly in PKS. CONCLUSION: Our study reinforces the association between brain abnormalities and PKS, and documents a diverse neurogenetic basis for structural brain abnormalities and impaired function in children diagnosed with this rare disorder.

Cytokine levels and associations with symptom severity in male and female children with autism spectrum disorder.

Background: Autism spectrum disorders (ASDs) are complex, pervasive, and heterogeneous neurodevelopmental conditions with varying trajectories, significant male bias and largely unknown etiology. However, an understanding of the biological mechanisms driving pathophysiology is evolving. Immune system aberrations, as identified through cytokine profiles, are believed to have a role in ASD. Altered cytokine levels may facilitate identification of ASD subtypes as well as provide biological markers of response to effective treatments. Research exploring the relationship between cytokine profiles and ASD symptoms is, however, in its infancy. The objective of this study was to explore relationships between cytokine levels and the severity of ASD and other clinical traits. Methods: Multiplex assay techniques were used to measure levels of 27 cytokines in plasma samples from a cohort of 144 children diagnosed with ASD. Results: Overall, results showed a significant negative association between platelet-derived growth factor (PDGF)-BB, and the severity of ASD symptoms. Furthermore, a significant interaction with sex suggested a different immune profile for females compared to males. ASD symptom severity was negatively associated with levels of 4 cytokines, IL-1ß, IL-8, MIP-1ß, and VEGF, in females, but not in males. Conclusions: Results of the present study suggest that an altered cytokine response or profile is associated with the severity of ASD-related symptoms, with sex a potential modifier of this relationship. Further research in larger populations which recognizes the importance of sex comparisons and longitudinal assessments are now required to extend and further describe the role of the immune system in ASD.

Reinforcing the association between distal 1q CNVs and structural brain disorder: A case of a complex 1q43-q44 CNV and a review of the literature.

Copy Number Variations (CNVs) comprising the distal 1q region 1q43-q44 are associated with neurological impairments, structural brain disorder, and intellectual disability. Here, we report an extremely rare, de novo case of a 1q43-q44 deletion with an adjacent duplication, associated with severe seizures, microcephaly, agenesis of the corpus callosum, and pachygyria, a consequence of defective neuronal migration disorder. We conducted a literature survey to find that our patient is only the second case of such a 1q43-q44 CNV ever to be described. Our data support an association between 1q43-q44 deletions and microcephaly, as well as an association between 1q43-q44 duplications and macrocephaly. We compare and contrast our findings with previous studies reporting on critical 1q43-q44 regions and their constituent genes associated with seizures, microcephaly, and corpus callosum abnormalities [Ballif et al., 2012; Hum Genet 131:145-156; Nagamani et al., 2012; Eur J Hum Genet 20:176-179]. Taken together, our study reinforces the association between 1q43-q44 CNVs and brain disorder.

Development and validation of a family history screening questionnaire in Australian primary care.

PURPOSE: We aimed to validate a family history screening questionnaire in an Australian primary care population designed to identify people at increased risk for breast, ovarian, colorectal, and prostate cancer; melanoma; ischemic heart disease; and type 2 diabetes. METHODS: We prospectively validated the questionnaire in 6 general practices in Perth, Western Australia among 526 patients aged 20 to 50 years who responded to a single invitation from their general practice. They completed the 15-item questionnaire before a reference standard 3-generation pedigree was obtained by a genetic counselor blinded to the questionnaire responses. We calculated diagnostic performance statistics for the questionnaire using the pedigree as the reference standard. RESULTS: A combination of 9 questions had the following diagnostic performance, expressed as value (95% CI), to identify increased risk of any of the 7 conditions: area under the receiver operating characteristic curve 84.6% (81.2%-88.1%), 95% sensitivity (92%-98%), and 54% specificity (48%-60%). The combination of questions to detect increased risk had sensitivity of 92% (84%-99%) and 96% (93%-99%) for the 5 and 6 conditions applicable only to men and women, respectively. The specificity was 63% (28%-52%) for men and 49% (42%-56%) for women. The positive predictive values were 67% (56%-78%) and 68% (63%-73%), and the false-positive rates were 9% (0.5%-17%) and 9% (3%-15%) for men and women, respectively. CONCLUSIONS: This simple family history screening questionnaire shows good performance for identifying primary care patients at increased disease risk because of their family history. It could be used in primary care as part of a systematic approach to tailored disease prevention.

Brief report: do the nature of communication impairments in autism spectrum disorders relate to the broader autism phenotype in parents?

Extensive empirical evidence indicates that the lesser variant of Autism Spectrum Disorders (ASD) involves a communication impairment that is similar to, but milder than, the deficit in clinical ASD. This research explored the relationship between the broader autism phenotype (BAP) among parents, an index of genetic liability for ASD, and proband communication difficulties. ASD probands with at least one BAP parent (identified using the Autism Spectrum Quotient) had greater structural and pragmatic language difficulties (assessed using the Children's Communication Checklist-2) than ASD probands with no BAP parent. This finding provides support for the position that genetic liability for ASD is associated with increased communication difficulties across structural and pragmatic domains.

SNP-based arrays complement classic cytogenetics in the detection of chromosomal aberrations in Wilms' tumor.

Wilms' tumors have characteristic chromosomal abnormalities, such as the 11p13 deletion, in a subset of cases. This is one of the very few reports comparing single nucleotide polymorphism (SNP) array analysis with conventional karyotyping of Wilms' tumors. A total of 43 frozen tumor samples were analyzed using the Affymetrix Cytogenetics Whole-Genome 2.7M array. The findings from the SNP array analysis were then compared with those from conventional karyotyping. A comparison between SNP array and conventional karyotype findings was possible in 38 of 43 specimens (88.4%). The SNP array and classic cytogenetic results were concordant in 33 of 38 specimens (87%). SNP array analysis was able to support the findings of classic cytogenetics. The SNP array detected regions of loss of heterozygosity (LOH) in 41 of 43 (95%) specimens. However, it did not detect balanced translocations and inversions that were observed by conventional cytogenetics. Our results show that the data generated from these platforms are complementary. The SNP array also detected additional gains and losses as well as regions of LOH with associated disomy, which are likely to represent segmental uniparental disomy. The observed discrepancies can be explained by the inherent limitations of each technique.

Quality standards and samples in genetic testing.

The most critical performance indicator for medical laboratories is the delivery of accurate test results. In any laboratory, there is always the possibility that random or systematic errors may occur and place human health and welfare at risk. Laboratory quality assurance programmes continue to drive improvements in analytical accuracy. The most rigorously scrutinised data on laboratory errors, which come from transfusion medicine, reveal that the incidence of analytical errors has fallen to levels where most of the residual risk is now found in preanalytical links in the chain from patient to result, particularly activities associated with ordering of tests and sample collection. This insight is important for genetic testing because, like pretransfusion testing of patients with unknown blood groups, a substantial proportion of genotyping results cannot be immediately verified. An increasing number of clinical decisions, associated personal and social choices, and legal outcomes are now influenced by genetic test results in the absence of other confirmatory data. An incorrect test result may lead to unnecessary and irreversible interventions, which may in themselves have associated risks for the patient, inaccurate risk assessment regarding the disease, missed opportunities for disease prevention or even wrongful conviction in a court of law. Unfortunately, there is limited information available about the risk of preanalytical errors associated with, and few published guidelines regarding, sample collection for genetic testing. The growing number and range of important decisions made on the basis of genetic findings warrant a reappraisal of current standards to minimise risks in genetic testing.

A retrospective audit of family history records in short-stay medical admissions.

OBJECTIVE: To retrospectively review the frequency and adequacy of family histories recorded from patients admitted to a short-stay medical unit in a tertiary teaching hospital. DESIGN, SETTING AND PATIENTS: A formal audit of the medical records of 300 randomly selected patients who were admitted to the Royal Perth Hospital short-stay medical unit between July and December 2007. MAIN OUTCOME MEASURE: Proportion of patient records with family history documents. RESULTS: Of the 300 patient records, 48 (16.0%) contained a family history with specific details about the presence or absence of a medical condition in at least one relative. Overall, 221 records (73.7%) had no family history documented. There was a trend towards more frequent and detailed family histories being recorded from younger patients and those presenting with chest pain. CONCLUSIONS: Family history was seldom documented in patients admitted to a short-stay medical unit in a tertiary teaching hospital. An increased focus on family history taking among acutely ill patients offers potential health gains for patients and their high-risk relatives, particularly as preventive or risk-reducing health care strategies are emerging for a growing number of heritable disorders.

Maternal family history of diabetes is associated with a reduced risk of cardiovascular disease in women with type 2 diabetes: the Fremantle Diabetes Study.

OBJECTIVE: To investigate whether parental family history of diabetes influences cardiovascular outcomes in type 2 diabetes. RESEARCH DESIGN AND METHODS: We studied 1,294 type 2 diabetic patients (mean age 64.1 years, 51.2% female) recruited to a community-based cohort study from 1993 to 1996 and followed until mid-2006. A data linkage system assessed all-cause and cardiac mortality, incident myocardial infarction, and stroke. Cox proportional hazards modeling was used to determine the influence of maternal or paternal family history on these outcomes. RESULTS: A maternal family history of diabetes was reported by 20.4% of the cohort, 8.3% reported paternal family history, and 2.0% reported both parents affected. Maternal and paternal family history was associated with earlier age of diabetes onset, and maternal family history was associated with worse glycemic control. For all patients, maternal family history was significantly associated with reduced risk of all-cause mortality and cardiac mortality. When analyzed by sex, maternal family history had no effect on male patients, whereas female patients with diabetic mothers had significantly reduced hazard ratios for death from all causes (0.63 [95% CI 0.41-0.96]; P = 0.033), for death from cardiac causes (0.32 [0.14-0.72]; P = 0.006), and for first myocardial infarction (0.45 [0.26-0.76]; P = 0.003). Paternal family history status was not associated with these outcomes. CONCLUSIONS: A maternal family history of diabetes confers relative protection against cardiovascular disease in female patients but not in male patients with type 2 diabetes. Paternal family history is associated with risks equivalent to those without a family history of diabetes. Some of the clinical heterogeneity of type 2 diabetes is related to maternal transmission effects with differential impact on male and female patients.

Linking MECP2 and pain sensitivity: the example of Rett syndrome.

Recent animal studies suggest links between MeCP2 function and sensitivity to pain. This study investigated the nature and prevalence of atypical pain responses in Rett syndrome and their relationships with specific MECP2 mutations. Families enrolled in the Australian Rett Syndrome Database (ARSD) and InterRett database participated in this study. Cases with a known MECP2 pathogenic mutation, whose families had completed a questionnaire on registration and had answered questions on pain sensitivity were included (n = 646). Logistic regression was used to analyze relationships between the atypical pain responses and genotype. Descriptions of decreased pain sensitivity were content analyzed. The prevalence estimate of reporting an abnormal pain response was 75.2% and a decreased sensitivity to pain was 65.0% in the population-based ARSD. Families of ARSD and InterRett subjects with a C-terminal (OR 2.6; 95% CI 0.8-8.0), p.R168X (OR 2.1; 95% CI 0.7-6.1), or p.R306C (OR 2.7; 95% CI 0.8-9.6) mutation were more likely to report decreased sensitivity to pain. Parents and carers described decreased and delayed responses in situations judged likely to cause pain such as injections, falls, trauma, and burns. This study has provided the first precise estimate of the prevalence of abnormal sensitivity to pain in Rett syndrome but specific relationships with genotype are not yet clear. Clinical practice should include a low threshold for the clinical assessment of potential injuries in Rett syndrome.

Cells of epithelial lineage are present in blood, engraft the bronchial epithelium, and are increased in human lung transplantation.

BACKGROUND: There is a growing expectation that cell-based therapies will prove effective for a wide range of conditions including lung diseases such as cystic fibrosis. The promise of these therapies will depend largely on effective delivery and engraftment. In this study, in the setting of human lung transplantation, we sought to determine whether exogenous epithelial cells are able to engraft the transplanted organ and if cells of a similar phenotype could be detected in peripheral blood. METHODS: Cells obtained from bronchial brushings and peripheral blood were analyzed via dual fluorescent in situ hybridization/fluorescent immunohistochemistry (FISH/IHC), short tandem repeat polymerase chain reaction (STR-PCR) and flow cytometry. RESULTS: In 2 of 3 gender-mismatched patients we observed limited (5.9% to 6.8% by STR-PCR and 3.5% to 4% by FISH/IHC) engraftment of the bronchial epithelium by exogenous epithelial cells. Engrafting cells were CD34(-) CD15(-) CD68(-) c-Kit(-), but expressed CXCR4 on the cell surface. Cells with a similar phenotype were also identified in peripheral blood. In 8 patients, at 2 to 66 months post-transplant, 0.57 +/- 0.17% of CD14(-) peripheral blood mononuclear cells were of epithelial lineage. Almost all were CD45(+) and most expressed CXCR4 on the cell membrane. Cells of epithelial lineage were also identified in peripheral blood in healthy individuals but in much lower numbers (0.08 +/- 0.01%, p < 0.05). CONCLUSIONS: Cells of epithelial lineage are detectable in peripheral blood and are able to engraft the bronchial epithelium in humans. Cell numbers are increased in lung transplantation.

Unified criteria for ultrasonographic diagnosis of ADPKD.

Individuals who are at risk for autosomal dominant polycystic kidney disease are often screened by ultrasound using diagnostic criteria derived from individuals with mutations in PKD1. Families with mutations in PKD2 typically have less severe disease, suggesting a potential need for different diagnostic criteria. In this study, 577 and 371 at-risk individuals from 58 PKD1 and 39 PKD2 families, respectively, were assessed by renal ultrasound and molecular genotyping. Using sensitivity data derived from genetically affected individuals and specificity data derived from genetically unaffected individuals, various diagnostic criteria were compared. In addition, data sets were created to simulate the PKD1 and PKD2 case mix expected in practice to evaluate the performance of diagnostic criteria for families of unknown genotype. The diagnostic criteria currently in use performed suboptimally for individuals with mutations in PKD2 as a result of reduced test sensitivity. In families of unknown genotype, the presence of three or more (unilateral or bilateral) renal cysts is sufficient for establishing the diagnosis in individuals aged 15 to 39 y, two or more cysts in each kidney is sufficient for individuals aged 40 to 59 y, and four or more cysts in each kidney is required for individuals > or = 60 yr. Conversely, fewer than two renal cysts in at-risk individuals aged > or = 40 yr is sufficient to exclude the disease. These unified diagnostic criteria will be useful for testing individuals who are at risk for autosomal dominant polycystic kidney disease in the usual clinical setting in which molecular genotyping is seldom performed.

MECP2 genomic structure and function: insights from ENCODE.

MECP2, a relatively small gene located in the human X chromosome, was initially described with three exons transcribing RNA from which the protein MeCP2 was translated. It is now known to have four exons from which two isoforms are translated; however, there is also evidence of additional functional genomic structures within MECP2, including exons potentially transcribing non-coding RNAs. Accompanying the recognition of a higher level of intricacy within MECP2 has been a recent surge of knowledge about the structure and function of human genes more generally, to the extent that the definition of a gene is being revisited. It is timely now to review the published and novel functional elements within MECP2, which is proving to have a complexity far greater than was previously thought.

Noncitrus fruits as novel dietary environmental modifiers of iron stores in people with or without HFE gene mutations.

OBJECTIVE: To investigate whether citrus fruit, noncitrus fruit, and other dietary factors act as environmental modifiers of iron status in the absence or presence of hemochromatotic HFE gene mutations. PARTICIPANTS AND METHODS: Iron studies, HFE genotypic analyses, and dietary data from a survey conducted from March 21, 1994, through December 15, 1995, were analyzed for a group of 2232 residents (1105 men, 1127 women) aged 20 to 79 years recruited from the community electoral roll of Busselton in Western Australia. Data were analyzed by linear regression analysis and analysis of covariance. RESULTS: Higher levels of fresh fruit intake (excluding citrus fruits and citrus juices) had a significant protective effect (P=.002) against high body iron status as gauged by ferritin levels in men, irrespective of HFE genotype. Consumption of 2 or more pieces of fruit per day on average reduced mean serum ferritin levels by 20% compared with average consumption of less than 1 piece of fruit per day. This effect was not observed in women. Consumption of citrus fruits and citrus juices had no significant effects in either sex. No protective effects were observed for tea consumption or any other dietary factors studied. Red meat and alcohol consumption correlated with high body iron stores (P<.05), consistent with previous studies, but did not interact with fruit with regard to effects on serum ferritin (P>.05). CONCLUSION: Noncitrus fruits are environmental modifiers of iron status independent of HFE genotype. This could have important implications for the provision of evidence-based dietary advice to patients with other iron-storage disorders.

The diagnosis of autism in a female: could it be Rett syndrome?

The overlap between autism and Rett syndrome clinical features has led to many cases of Rett syndrome being initially diagnosed with infantile autism or as having some autistic features. Both conditions seriously disrupt social and language development and are often accompanied by repetitive, nonpurposeful stereotypic hand movements. The aims of this study were to compare the early and subsequent clinical courses of female subjects with Rett syndrome categorised by whether or not a diagnosis of autism had been proposed before Rett syndrome had been diagnosed and compare the spectrum of methyl-CpG binding protein 2 (MECP2) mutations identified among the two groups. This study made use of a total of 313 cases recorded in two databases: the Australian Rett Syndrome Database (ARSD) and the International Rett Syndrome Phenotype Database (InterRett). Cases with an initial diagnosis of autism had significantly milder Rett syndrome symptoms and were more likely to remain ambulant, to have some functional hand use and not to have developed a scoliosis. Females with the p.R306C or p.T158M mutations in the MECP2 gene were more likely to have an initial diagnosis of autism, and the specific Rett syndrome symptoms were noted at a later age. We recommend that females who are initially considered to have autism be carefully monitored for the evolution of the signs and symptoms of Rett syndrome.

Directions for clinical practice improvement in HFE gene mutation testing.

OBJECTIVE: To audit the clinical indications for HFE gene mutation testing in a consecutive series of requests. DESIGN: Retrospective audit of reasons prompting 187 HFE test requests received between June 2003 and June 2005, by examination of the request form, hospital notes (when available) and, when required, information from the referring doctor. SETTING: A tertiary care public teaching hospital laboratory, Perth, Western Australia. MAIN OUTCOME MEASURES: Reasons prompting requests for HFE genotype testing and compliance with accepted clinical indications (biochemical evidence of iron overload on repeated samples, or a first-degree relative with either haemochromatosis or a C282Y mutation). RESULTS: Insufficient clinical details in requests prevented the inclusion of interpretive comments in HFE genotype reports in 70 of 187 cases (37%). Re-evaluation after collation of the missing details for all but seven requests revealed that 103 of the 180 auditable requests (57%) had been prompted for reasons other than biochemical evidence of iron accumulation or family history. CONCLUSIONS: A substantial proportion of HFE genotype test requests are made for inappropriate reasons. Clinical practice could be improved by educating doctors on the practical utility of this genetic test and by laboratories taking steps to secure the clinical information needed to include appropriate interpretive comments in their reports.

Seizures in Rett syndrome: an overview from a one-year calendar study.

BACKGROUND: Rett syndrome is a neurodevelopmental disorder mainly affecting females. It is principally caused by mutations in the MECP2 gene. Seizures occur in about 80% of subjects but there has been little research into the factors contributing to their frequency. AIMS: To investigate seizure frequency in Rett syndrome and its relationship with other factors, including genetic characteristics and the use of anti-epileptic drugs. METHODS: Information on daily seizure occurrence and health service utilization and monthly anti-epileptic drug use was provided on 162 Rett syndrome cases for a calendar year. Age at onset of seizures, developmental history and other clinical and genetic characteristics were obtained from a contemporaneously completed questionnaire and from the Australian Rett Syndrome Database. Negative binomial regression was used to investigate factors associated with seizure rates. RESULTS: Seizure rates were highest in the 7-12 year age group. They were lower in those with p.R294X, p.R255X mutations and C terminal mutations. Those who had early developmental problems and poorer mobility had higher seizure rates as did those with greater clinical severity and poorer functional ability. Many different combinations of medications were being used with carbamazepine, sodium valproate and lamotrigine either singly or in combination with another being the most common. CONCLUSIONS: Seizure frequency in Rett syndrome is age-dependent, more common in those with more severe early developmental problems and influenced by mutation type.

Recommendations of the 2006 Human Variome Project meeting.

Lists of variations in genomic DNA and their effects have been kept for some time and have been used in diagnostics and research. Although these lists have been carefully gathered and curated, there has been little standardization and coordination, complicating their use. Given the myriad possible variations in the estimated 24,000 genes in the human genome, it would be useful to have standard criteria for databases of variation. Incomplete collection and ascertainment of variants demonstrates a need for a universally accessible system. These and other problems led to the World Heath Organization-cosponsored meeting on June 20-23, 2006 in Melbourne, Australia, which launched the Human Variome Project. This meeting addressed all areas of human genetics relevant to collection of information on variation and its effects. Members of each of eight sessions (the clinic and phenotype, the diagnostic laboratory, the research laboratory, curation and collection, informatics, relevance to the emerging world, integration and federation and funding and sustainability) developed a number of recommendations that were then organized into a total of 96 recommendations to act as a foundation for future work worldwide. Here we summarize the background of the project, the meeting and its recommendations.