Articles

Epigenetic Regulation of Oxysterol Formation

Steve Meaney — Wed, 05 Jun 2013 09:06:34 PDT

Oxysterols are oxygenated derivatives of cholesterol that may be formed by either enzymatic or non-enzymatic mechanisms. Expression of the genes responsible oxysterol synthesis (GROS) is known to be restricted across different tissues and cell types. Regulation of the transcription of GROS and the activity of their enzyme transcripts has been the subject of intense activity for many years. Recent studies have sought to decipher the mechanism(s) that underpin the restricted expression of the GROS. Available data indicates that epigenetic mechanisms have an important role to play in the control of the expression of GROS. In the current review we summarize the available evidence for the epigenetic regulation of these genes.

Apoptosis is Signalled Early by Low Doses of Ionizing Radiation in a Radiation-Induced Bystander Effect

Hayley Furlong et al. — Wed, 03 Apr 2013 05:06:02 PDT

It is known that ionising radiation (IR) induces a complex signalling apoptotic cascade post-exposure to low doses ultimately to remove damaged cells from a population, specifically via the intrinsic pathway. Therefore, it was hypothesised that bystander reporter cells may initiate a similar apoptotic response if exposed to low doses of IR (0.05 Gy and 0.5 Gy) and compared to directly irradiated cells. Key apoptotic genes were selected according to their role in the apoptotic cascade; tumour suppressor gene TP53, pro-apoptotic Bax and anti-apoptotic Bcl2, pro-apoptotic JNK and anti-apoptotic ERK, initiator caspase 2 and 9 and effector caspase 3, 6 and 7. The data generated consolidated the role of apoptosis following direct IR exposure for all doses and time points as pro-apoptotic genes such as Bax and JNK as well as initiator caspase 7 and effector caspase 3 and 9 were up-regulated. However, the gene expression profile for the bystander response was quite different and more complex in comparison to the direct response. The 0.05 Gy dose point had a more significant apoptosis gene expression profile compared to the 0.5 Gy dose point and genes were not always expressed within 1 hour but were sometimes expressed 24 hrs later. The bystander data clearly demonstrates initiation of the apoptotic cascade by the up-regulation of TP53, Bax, Bcl-2, initiator caspase 2 and effector caspase 6. The effector caspases 3 and 7 of the bystander samples demonstrated down-regulation in their gene expression levels at 0.05 Gy and 0.5 Gy at both time points therefore not fully executing the apoptotic pathway. Extensive analysis of the mean-fold gene expression changes of bystander data demonstrated that the apoptosis is initiated in the up-regulation of pro-apoptotic and initiator genes but may not very well be executed to final stages of cell death due to down-regulation of effector genes.

Weaning Onto Solid foods: Some of the Challenges

Annemarie Bennett et al. — Tue, 02 Apr 2013 01:26:05 PDT

Weaning - the transition from milk to solid food - influences life-long health. Dietary challenges during weaning include providing sufficient critical nutrients such as iron with minimal added sugar and fat and no added salt. This study assessed the inclusion of iron-containing red meat in infant diets before age one year, and the Irish commercial baby food environment. Of mothers with an infant under 30 months of age who were surveyed in shopping centres in Ireland (n195), 82% (n159) reported wanting more weaning information. A quarter (n24) of infants over age 12 months (n97) received no iron-containing red meat before age one year. A scan of commercial baby foods in Ireland identified 448 products. While all complied with baby food legislation, 15% (n69) were intrinsically high in sugar and fat, or contained added salt. This study indicates the need for specific guidance on best infant feeding practice in Ireland.

Protein Kinase C Delta is a Substrate of Tissue Transglutaminase and a Novel Autoantigen in Coeliac Disease

Greg Byrne et al. — Tue, 19 Mar 2013 03:51:11 PDT

Post-translational modification of proteins by deamidation or transamidation by tissue transglutaminase (tTG) has been suggested as a possible mechanism for the development of autoimmunity. Sequence analysis of protein kinase C delta (PKCδ) identified an amino acid motif that suggested the possibility that PKCδ was a glutamine substrate of tTG and MALDI-TOF analysis of synthesised peptides from PKCδ proved that this was the case. Polymerisation experiments using recombinant tTG and biotinylated hexapeptide substrate incorporation assays demonstrated that PKCδ is a substrate for tTG-mediated transamidation. Elevated levels of anti-PKCδ antibodies were detected in sera from patients with coeliac disease (pb0.0001) but not from patients with other autoimmune disorders. These data suggest that a subset of patients with coeliac disease produce autoantibodies against PKCδ and that this response may stem from a tTG–PKCδ substrate interaction.

Early Formula Feeding Practices and Their Potential Contribution To Later Obesity Risk

Roslyn Tarrant — Thu, 03 Jan 2013 02:10:55 PST

Background and Aims: Early feeding practices, including early introduction to solid foods and overfeeding, are known risk factors for childhood obesity. This study aimed to assess maternal formula feeding practices and infant formula feeding patterns, factors that are known to potentially contribute to later obesity risk.

Methods: This prospective observational study involved the recruitment and follow-up of 450 eligible mother-infant pairs to 6 weeks postpartum. Data related to formula milk consumption patterns, formula type/brand changing, additions of solid foods to bottle feeds were examined, and available infant weight measurements at 6 weeks recorded.

Results: In total, 368 (81.8%) mothers provided any formula milk to their infants at 6 weeks; of these, 14 (3.8%) reported to adding solid foods to their infant’s bottle feeds. Almost 50% of formula feeding mothers (n = 181) reported to changing their infant’s formula type/brand at least once during the first 6 weeks, mainly due to increased hunger and feeding frequency (2-3 hourly) (54.8%). Where 6 week infant weight measurements were available (n = 184), a mean of 205ml (SD 45ml) of formula milk/kilogram body weight/day was consumed by these infants.

Conclusion: Several formula feeding practices with potential implications for later obesity risk were identified in this study including premature introduction to solids (≤ 6 weeks) and consumption of excessive formula milk volumes at 6 weeks relative to infant feeding guidelines. Early provision of recommended feeding guidelines including specific advice on age-appropriate milk volumes to parents who formula feed should be considered in obesity prevention programmes.

Mothers Who Formula Feed: Their Practices, Support Needs and Factors Influencing Their Infant Feeding Decision.

Roslyn Tarrant — Thu, 03 Jan 2013 01:46:11 PST

The majority of mothers in Ireland provide formula milk to their infants during the initial weeks postpartum; however, data are lacking on their formula feeding practices and support needs. This prospective Dublin-based observational study, which included 450 eligible mother-term infant pairs recruited and followed up to 6 months postpartum, aimed to advance our understanding of maternal formula feeding practices, their reasons for deciding to formula feed, sources of feeding information and perceived support needs; insights into infant formula milk consumption patterns in relation to current feeding guidelines are also provided. In summary, the vast majority of infants at 6 weeks were provided with formula milk (n = 368; 81.8%). Positive maternal perceptions of formula feeding were among the most frequently reported reasons underlying mothers’ decision to formula feed (e.g. convenience, 17.3%). Potential public health concerns over the large formula milk volumes consumed by infants (mean 205ml/kilogram/day) relative to infant feeding guidelines (150ml/kilogram/day) were raised from this study. Some mothers continue to add solid foods to infant bottle feeds at 6 weeks (3.8%) and 6 months (6%), a non-recommended feeding practice posing a choking risk for infants. Crucially, this study highlights the need to provide greater support and information to mothers who decide to formula feed postpartum including practical information on sterilisation and formula reconstitution. While breastfeeding promotion and research continues to be a public health priority in Ireland, addressing the support and information needs of mothers who formula feed, an underrepresented and understudied population in the literature, also needs to be considered to ensure optimal health and safety for their infants.

450DNA Methylation Array Analysis of Chronic Lymphocytic Leukaemia Reveals Global Methylation to be Relatively Stable Over Time and Remarkably Similar in Cells Derived From Resting and Proliferative Compartments

Nicola Cahill et al. — Mon, 17 Sep 2012 03:43:18 PDT

The advent of global investigations has begun to unravel the functional involvement of DNA methylation in leukemogenesis. Previously, we identified divergent chronic lymphocytic leukaemia (CLL) subgroups to have differential methylation patterns effecting key canonical pathway, proliferation and apoptotic genes. Despite these advances, in CLL cells, little to no knowledge exists regarding the extent to which DNA methylation changes with respect to time and exposure to different microenvironments. For the first time, using high-resolution 450K DNA methylation arrays, the DNA methylation profiles of paired diagnostic/follow-up samples from 9 IGHVmutated/ treated and 9 IGHV-unmutated/untreated patients, as well as 10 patient-matched peripheral blood (PB) and lymph node (LN) samples were investigated. On a larger scale to our previous 27K array study, we revealed 2239 CpG sites as differentially methylated between IGHV-mutated and unmutated CLL patients. Interestingly, the majority of sites were positioned outside CpG islands and promoters. Novel findings include differential DNA methylation of CpG sites within known differentially expressed CLL prognostic genes CLLU1 and LPL, where methylation was notably higher in IGHV-mutated cases. Additionally, genes occupying TGF-ß and NF-B/TNFR1 pathways and large numbers of polycomb targets were differentially methylated. Over time, few large recurrent DNA methylation changes were noted among the subgroups. Although a larger number of non-recurrent differentially methylated sites were identified in IGHV-unmutated relative to IGHV-mutated cases over time, these changes equated to a low (

Development and Validation of a Novel Reporter Assay for Human Papillomavirus Type 16 Late Gene Expression

Beatrice Orru et al. — Wed, 28 Mar 2012 07:42:53 PDT

To facilitate the investigations of HPV-16 late gene expression HPV-16 reporter plasmids were generated using previously described sub-genomic HPV-16 plasmids, named pBEL and pBELM, that, similar to the full viral genome, produce primarily HPV-16 early mRNAs and very little, if any, late mRNAs in cervical cancer cells. The HPV-16 late L1 gene was replaced by the chloramphenicol acetyltransferase (CAT) reporter gene, or green fluorescent protein (GFP), preceded by the poliovirus internal ribosome entry site (IRES). Results show that the reporter genes mimic the expression of L1 from these plasmids. For example, overexpression of adenovirus E4orf4 protein (E4orf4), polypyrimidine tract binding protein (PTB), arginine/serinerich SRp30c protein (SRp30c) or alternative splicing factor/splicing factor 2 (ASF/SF2) induced an increased expression of CAT or GFP. Stable cell lines with reporter plasmids pBELCAT and pBELMCAT were also generated. An induction of CAT was observed in HPV-16 reporter cell lines in the presence of the small molecule phorbol 12-myristate 13-acetate (TPA). Further experiments identified the TPA-inducible, hnRNP A2/B1 protein as a regulator of HPV-16 late gene expression. In conclusion, the HPV-16 reporter plasmids and reporter cell lines described herein can be used to identify small molecules and cellular factors that regulate HPV-16 gene expression.

Factors Associated with Duration of Breastfeeding in Ireland: Potential Areas for Improvement

Roslyn Tarrant et al. — Thu, 22 Mar 2012 09:14:11 PDT

There is a need to comprehensively examine why mothers in Ireland discontinue breastfeeding early and to explore thefactors influencing duration of breastfeeding during the first 6 months postpartum. Findings from this study provide valuabledirection for future strategies and interventions aimed at increasing breastfeeding duration rates in Ireland.

The Positive Role of Breastfeeding on Infant Health during the First 6 Weeks: Findings from a Prospective Observational Study Based on Maternal Reports

Roslyn Tarrant et al. — Thu, 22 Mar 2012 09:09:32 PDT

This study aimed to report on adverse infant and maternal clinical outcomes, and investigate the relationship between infant feedingpractice and such adverse clinical outcomes in infants during the first 6 weeks postpartum. From an eligible sample of 450 motherterminfant pairs recruited from the Coombe Women and Infants University Hospital in Dublin, 27.1% of infants (n=122) werematernally reported to have had an illness during the first 6 weeks that necessitated the provision of prescribed medication ± generalpractitioner/paediatrician attendance ± hospitalisation. Of these, 90 infants had ≥1 episode of infection ± viral ± gastro-intestinalrelatedcondition. After adjustment, ‘any’ breastfeeding to 6 weeks was protective against such adverse infant outcomes (adjustedodds ratio [aOR] 0.44, P = 0.022). Attendance to the GP/paediatrician for > 1 visit (aOR 3.44, P = 0.000) and multiparity (aOR 1.76,P = 0.041) were also positively associated with such adverse infant outcomes. To decrease infant morbidity rates in Ireland,government investment in breastfeeding promotion, support and research should be a continued public health priority.

Maternal and Infant Nutritional Supplementation Practices in Ireland: Implications for Clinicians and Policymakers

Roslyn Tarrant et al. — Thu, 11 Aug 2011 01:56:17 PDT

This prospective Irish observational study examined maternal and infant nutritional supplement use. From an initial sample of 539 mothers recruited from the Coombe Women and Infants University Hospital in Dublin (during 2004-2006), 450 eligible mothers werefollowed up at 6 weeks and 6 months postpartum. Only 200 women (44.4%) complied with peri-conceptional folic acid at therecommended time with strong social patterning associated with its uptake. Almost 10% of the sample (n=44) consumed acombined multivitamin and mineral supplement during pregnancy. A vitamin D-containing supplement was provided to only 5 (1.1%)and 15 (3.3%) infants at 6 weeks and 6 months, respectively. A national guideline that advises on adequate and safe use of bothvitamin and multivitamin supplements during pregnancy with particular reference to vitamin A and D is warranted. Given there-emergence of rickets in Ireland, and the reported morbidities associated with vitamin D insufficiency, promoting and monitoringcompliance with 200IU [5μg] daily vitamin D supplements to all infants particularly those from higher risk groups from birth to 1 year,should be a public health priority.

Letter to the Editor

Charlotte Johnston Molloy et al. — Fri, 29 Jul 2011 04:00:41 PDT

Maternal Health Behaviours During Pregnancy in an Irish Obstetric Population and Their Assocations with Socio-Demographic and Infant Characteristics

Roslyn Tarrant et al. — Mon, 04 Jul 2011 07:02:49 PDT

Objectives: To examine the prevalence and combined occurrence of peri-conceptional folic acid (FA) supplement use, smoking and alcohol consumption during pregnancy in a sample of women in Dublin, and determine the factors associated with these health behaviours.

Subjects/Methods: A prospective observational study (2004-2006) involving the recruitment of 491 pregnant women from antenatal clinics in a Dublin maternity hospital, with postpartum follow-up of 450 eligible mothers. Data on FA use, maternal smoking and alcohol consumption patterns during pregnancy were collected from the antenatal patient-administered questionnaire, which was completed by participants, and returned to the investigator on the day of recruitment.

Results: The median gestational age of women at recruitment was 36 weeks. A combined 24.2% of mothers commenced FA at the recommended time, avoided alcohol consumption and smoking during pregnancy. 35.3% of mothers reported to consuming alcohol, 20.9% smoked during pregnancy and 44.4% commenced FA at the recommended time. Mothers < 25 years were more likely to have not taken FA at the recommended time (adjusted odds ratio (aOR) 4.0, 95% confidence interval (CI): 1.64-9.77) and were more likely to have smoked during pregnancy (aOR 3.56, 95% CI: 1.32-9.57). Irish nationality positively predicted both alcohol consumption (aOR: 4.37, 95% CI: 1.88-10.15) and smoking (aOR: 10.92, 95% CI: 1.35-87.98) during pregnancy.

Conclusions: Educational efforts are still necessary to convince women of Irish nationality, in particular, of the adverse effects of smoking and alcohol consumption on foetal outcome. Women < 25 years should be specifically targeted in smoking cessation and FA promotional campaigns.

An Evaluation of MIRU-VNTR Analysis and Spoligotyping for Genotyping of M. Bovis Isolates and a Comparison with RFLP Typing

Joanne McLernon et al. — Thu, 16 Jun 2011 09:39:37 PDT

Common strain typing methods for differentiation of Mycobacterium bovis isolates include restriction endonuclease analysis (REA), restriction fragment length polymorphism (RFLP) analysis, spoligotyping and more recently, mycobacterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR) typing. Strain typing of Mycobacterium bovis isolates based on the variable-number tandem repeats of mycobacterial interspersed repetitive units (MIRU-VNTR) and on spoligotyping was evaluated in this study and these typing methods were compared with restriction fragment length polymorphism (RFLP) typing. A total of 386 M. bovis isolates from cattle, badgers and deer in the Republic of Ireland that had previously been typed by IS6110, polymorphic GC-rich sequence (PGRS) and direct repeat (DR) RFLP were included in the study. Spoligotyping and analysis of six VNTR loci (2163a, 2163b, 2165, 4052, 2996 and 1895) was performed on the samples. RFLP was the method that gave the greatest differentiation of strains with a Hunter Gaston discriminatory index (HGDI) of 0.927, the HGDI recorded for MIRU-VNTR was marginally lower at 0.918 and spoligotyping was the least discriminatory method with a HGDI of 0.7. Spoligotype SB0140 represented approximately 50% of the isolates. Within the group of isolates represented by SB0140 there was a much lower level of concordance between RFLP and MIRU-VNTR typing compared to groups represented by other spoligotypes. A combination of spoligotyping and MIRU-VNTR typing offered advantages over MIRU-VNTR typing alone. In a combined spoligotyping and MIRU-VNTR typing protocol the number of VNTR loci could be reduced to four (2163a, 2163b 2165 and 4052) while maintaining a high level of strain differentiation.

High-Density Screening Reveals a Different Spectrum of Genomic Aberrations in Chronic Lymphocytic Leukemia Patients with "stereotyped" IGHV3-21 and IGHV4-34 B-Cell Receptors

Millaray Marincevic et al. — Thu, 16 Jun 2011 09:34:02 PDT

Background
The existence of multiple subsets of chronic lymphocytic leukemia expressing ‘stereotyped’ Bcell receptors implies the involvement of antigen(s) in leukemogenesis. Studies also indicate that ‘stereotypy’ may influence the clinical course of patients with chronic lymphocytic leukemia, for example, in subsets with stereotyped IGHV3-21 and IGHV4-34 B-cell receptors;
however, little is known regarding the genomic profile of patients in these subsets.
Design and Methods
We applied 250K single nucleotide polymorphism-arrays to study copy-number aberrations and copy-number neutral loss-of-heterozygosity in patients with stereotyped IGHV3-21 (subset #2, n=29), stereotyped IGHV4-34 (subset #4, n=17; subset #16, n=8) and non-subset #2 IGHV3-21 (n=13) and non-subset #4/16 IGHV4-34 (n=34) patients.
Results
Over 90% of patients in subset #2 and non-subset #2 carried copy-number aberrations, whereas 75-76% of patients in subset #4 and subset #16 showed copy-number aberrations. Subset #2 and non-subset #2 patients also displayed a higher average number of aberrations compared to
patients in subset #4. Deletion of 13q was the only known recurrent aberration detected in subset #4 (35%); this aberration was even more frequent in subset #2 (79%). del(11q) was more frequent in subset #2 and non-subset #2 (31% and 23%) patients than in subset #4 and nonsubset
#4/16 patients. Recurrent copy-number neutral loss-of-heterozygosity was mainly detected on chromosome 13q, independently of B-cell receptor stereotypy.
Conclusions
Genomic aberrations were more common in subset #2 and non-subset #2 than in subset #4. The particularly high frequency of del(11q) in subset #2 may be linked to the adverse outcome reported for patients in this subset. Conversely, the lower prevalence of copy-number aberrations and the absence of poor-prognostic aberrations in subset #4 may reflect an inherently
low-proliferative disease, which would prevent accumulation of genomic alterations.

Endostatin Modulates VEGF-Mediated Barrier Dysfunction in the Retinal Microvascular Endothelium

Brenda Brankin et al. — Mon, 28 Mar 2011 01:38:14 PDT

Recent evidence indicates that the anti-angiogenic peptide endostatin may modulate some of the vasomodulatory effects of vascular endothelial growth factor (VEGF) in the retina, including reduction of blood retinal barrier function although it remains uncertain how endostatin promotes endothelial barrier properties. The current study has sought to examine how physiological levels of endostatin alters VEGF-induced inner BRB function using an in vitro model system and evaluation of occludin and ZO-1 regulatory responses. In addition, the ability of exogenous endostatin to regulate VEGF-mediated retinal vascular permeability in vivo was investigated.

Retinal microvascular endothelial cells (RMEC's) were exposed to various concentrations of endostatin. In parallel studies, RMEC monolayers were treated with vascular endothelial growth factor (VEGF₁₆₅). Vasopermeability of RMEC monolayers and occludin expression were determined.

Blood retinal barrier integrity was quantified in mouse retina using Evans Blue assay following intravitreal delivery of VEGF₁₆₅, endostatin or a VEGF/endostatin combination.

Endostatin increased the levels of expression of occludin whilst causing no significant change in FITC-dextran flux across the RMEC monolayer. Endostatin reversed the effects of VEGF₁₆₅-enhanced permeability between microvascular endothelial cells and induced phosphorylation of occludin. Evans Blue leakage from retinas treated with VEGF was 2.0 fold higher than that of contra-lateral untreated eyes (P<0.05) while leakage of eyes from endostatin treated animals was unchanged. When eyes were injected with a combination of VEGF₁₆₅ and endostatin there was a significant reduction in retinal vasopermeability when compared to VEGF-injected eyes (P<0.05).

We conclude that endostatin can promote integrity of the retinal endothelial barrier, possibly by preventing VEGF-mediated alteration of tight junction integrity. This suggests that endostatin may be of clinical benefit in ocular disorders where significant retinal vasopermeability changes are present.

Attitudes Towards and Beliefs about Nutrition and Health Among a Random Sample of Adults in the Republic of Ireland and Northern Ireland

John M. Kearney et al. — Mon, 21 Feb 2011 05:53:47 PST

Objectives: For effective healthy eating promotion, it is necessary to understand the attitudes towards and beliefs about nutrition of the general public. The objective of this study was to provide date on attitudes towards eating a healthy diet and the perceived need to alter eating habits from a random sample of adults in the Republic of Ireland and in Northern Ireland, using a self-administered questionnaire. Design: Cross-sectional survey using a self administered attitudinal questionnaire on beliefs and attitudes to healthy eating. Setting: The survey was carried out between October, 1997 and October, 1999 in the Republic of Ireland and in Northern Ireland. Subjects: A randomly selected sample of 1256 adults from the Republic of Ireland and Northern Ireland completed the attitudinal questionnaire Results: A majority of subjects (62%) perceived that they make conscious efforts to eat a healthy diet either most of the time or quite often, while just over half (52%) agreed that they do not need to make changes to their diet as it is healthy enough. Subjects most likely to make conscious efforts to try to eat a healthy diet were females, older subjects (51-64 years) and those with the highest intakes of fruit and vegetables and lowest quartile of fat (%food energy). When self-assesses adequacy of fruit and vegetables was examined, two-thirds of the total sample felt they ate too little fruit while just one-third felt they ate too little vegetables.

Developing a nutrition assessment tool for Irish pre-schools

Charlotte Johnston Molloy et al. — Tue, 08 Feb 2011 05:30:21 PST

Purpose The provision of nutritious food to children in full day care pre-schools is essential to ensure adequate child growth and development. This paper outlines the development of a nutrition assessment tool (Scored Evaluation Form) for this setting, and describes the nutrition practice findings measured by this tool in full day child care in Ireland. Design / methodology / approach This study involved two phases: a comprehensive literature review carried out on each criterion in the Scored Evaluation Form (SEF) to ensure best practice; use of the SEF in full day care pre-schools to assess their nutrition practice. Findings Use of the SEF demonstrated that portion sizes provided to infants and toddlers were inadequate. Poor provision of iron containing, vegetable and dairy foods was noted, as were poor meal time practices. The phrasing of certain criteria needs modification to avoid misinterpretation of portion size. Research limitations / implications With small modifications to clarify the portion size provided, the SEF can be used in the pre-school setting to ascertain nutrition practice. Practical implications The SEF requires testing to determine its utility as an intervention tool whereby its use may lead to positive changes in nutrition practice in the pre-school setting. Originality / value This paper outlines the development of a nutrition practice assessment tool for the full day child care setting in Ireland and describes previously unknown data gathered using this tool

Intrafamilial Phenotypic Variability in Friedreich Ataxia Associated With a G130V Mutation in the FRDA Gene

Dominick McCabe et al. — Mon, 24 Jan 2011 03:54:02 PST

Background: Most patients with Friedreich ataxia (FA) have a GAA trinucleotide repeat expansion in intron 1 of the FA gene (FRDA) on both arms of chromosome 9. However, some patients are compound heterozygotes and harbor a GAA expansion on one allele and a point mutation on the other. Compound heterozygous patients with FA who have a GAA expansion and a G130V mutation have been reported to have an atypical phenotype with a slow disease progression, minimal or no ataxia, or gait spasticity. Objective: To describe intrafamilial phenotypic variability in a GAA expansion/G130V mutation compound heterozygous family with FA. Setting: Tertiary referral university hospital setting. Patients and Methods: A 34-year-old man presented to our hospital with a 24-year history of stiff legs and mild unsteadiness of gait. Clinical examination showed a spastic paraparesis with normal to pathologically brisk deep tendon reflexes and mild left upper limb ataxia. His 27-year-old sister presented with a slowly proprogressive early-onset ataxic syndrome. She had ataxia of gait, mild to severe limb ataxia, and reduced or absent deep tendon reflexes, but no evidence of spasticity on examination. Results: Neurophysiologic investigations showed evidence of a sensory axonal neuropathy, and molecular genetic analysis showed that both siblings were compound heterozygotes with a GAA expansion and a G130V mutation. Conclusions: This report confirms that compound heterozygous patients with FA who have a GAA expansion and a G130V mutation may present with an ataxic phenotype and that intrafamilial phenotypic variability in these pedigrees can occur. It also emphasizes the importance of performing molecular genetic analysis for the GAA trinucleotide expansion in patients presenting with a spastic paraparesis of undetermined etiology, especially when there is neurophysiologic evidence of a sensory axonal neuropathy.

Typical Friedreich’s ataxia without GAA expansions and GAA expansions without typical Friedreich’s ataxia

Dominick McCabe et al. — Mon, 24 Jan 2011 03:54:01 PST

We clinically assessed and performed polymerase chain reaction analysis for the GAA trinucleotide repeat expansion in 103 patients from 73 families in Ireland, with a prior clinical diagnosis of Friedreich’s ataxia (FA) or an unclassified progressive ataxic syndrome. The patients were classified as “typical” or “atypical” FA according to Harding’s mandatory clinical diagnostic criteria. All patients underwent blood glucose analysis, and electrocardiography and echocardiography was performed in 99 and 101 patients, respectively. Mutation screening for expanded CAG trinucleotide repeats, associated with spinocerebellar ataxia (SCA) 1, 2, 3 and 6 was performed in 86 patients overall, including all GAA negative patients. Fortynine of 56 typical patients and 13 of 47 atypical patients were either homozygous or heterozygous for the GAA expansion. Seven patients with a typical FA phenotype were negative for the GAA expansion. Although one of these patients had vitamin E deficiency, and two had raised α-fetoprotein levels, three other GAA negative patients with a typical FA phenotype had no other identifiable cause for their ataxia, once again raising the possibility of locus heterogeneity in FA. It is also possible that these patients have two point mutations in the X25 gene, or that they have another ataxic syndrome mimicking the FA phenotype. Two families who were homozygous for the GAA expansion exhibited intrafamilial phenotypic variability. Only one GAA negative patient had the SCA 3 mutation, and this was the only patient in the study with a possible autosomal dominant inheritance pattern. In the homozygous GAA population typical patients had significantly more repeats on the smaller allele than atypical patients, and there was an inverse relationship between the number of repeats on the smaller allele and the age at presentation. There was also an inverse relationship between the repeat size on both the larger and the smaller of the two alleles and the age at becoming wheelchair bound. There was no significant relationship between repeat size and the other indices of disease severity, including the presence or absence of diabetes or cardiomyopathy. This is the first large study of an Irish population with progressive ataxia that has shown a similar phenotype/genotype relationship to studies of FA in other European and non-European populations. The relatively low sensitivity and specificity of Harding’s clinical diagnostic criteria must be appreciated when clinically assessing patients with a progressive ataxic syndrome. Although molecular genetic analysis now plays an essential role in diagnosis and classification, patients with a typical FA phenotype without any identifiable cause for their ataxia exist.