The genotype-phenotype landscape of familial amyotrophic lateral sclerosis in Australia.

Amyotrophic lateral sclerosis (ALS) is a clinically and genetically heterogeneous fatal neurodegenerative disease. Around 10% of ALS cases are hereditary. ALS gene discoveries have provided most of our understanding of disease pathogenesis. We aimed to describe the genetic landscape of ALS in Australia by assessing 1013 Australian ALS patients for known ALS mutations by direct sequencing, whole exome sequencing or repeat primed polymerase chain reaction. Age of disease onset and disease duration were used for genotype-phenotype correlations. We report 60.8% of Australian ALS families in this cohort harbour a known ALS mutation. Hexanucleotide repeat expansions in C9orf72 accounted for 40.6% of families and 2.9% of sporadic patients. We also report ALS families with mutations in SOD1 (13.7%), FUS (2.4%), TARDBP (1.9%), UBQLN2 (.9%), OPTN (.5%), TBK1 (.5%) and CCNF (.5%). We present genotype-phenotype correlations between these genes as well as between gene mutations. Notably, C9orf72 hexanucleotide repeat expansion positive patients experienced significantly later disease onset than ALS mutation patients. Among SOD1 families, p.I114T positive patients had significantly later onset and longer survival. Our report highlights a unique spectrum of ALS gene frequencies among patients from the Australian population, and further, provides correlations between specific ALS mutations with disease onset and/or duration.

Quantitative muscle ultrasound as a biomarker in Charcot-Marie-Tooth neuropathy.

OBJECTIVE: The utility of quantitative muscle ultrasound as a marker of disease severity in Charcot-Marie-Tooth (CMT) disease subtypes was investigated. METHODS: Muscle ultrasound was prospectively performed on 252 individual muscles from 21 CMT patients (9 CMT1A, 8 CMTX1, 4 CMT2A) and compared to 120 muscles from 10 age and gender-matched controls. Muscle ultrasound recorded echogenicity and thickness in representative muscles including first dorsal interosseus (FDI) and tibialis anterior (TA). RESULTS: Muscle volume of FDI and thickness of TA correlated with MRC strength. Muscle echogenicity was significantly increased in FDI (65.05 vs 47.09; p<0.0001) and TA (89.45 vs 66.30; p<0.0001) of CMT patients. In TA, there was significantly higher muscle thickness (23 vs 18 vs 16mm; p<0.0001) and lower muscle echogenicity (80 vs 95 vs 108; p<0.0001) in CMT1A compared to CMTX1 and CMT2A. This corresponded to disease severity based on muscle strength (MRC grading CMT1A vs CMTX1 vs CMT2A: 59 vs 48 vs 44; p=0.002). CONCLUSION: In CMT, quantitative muscle ultrasound of FDI and TA is a useful marker of disease severity. SIGNIFICANCE: The current findings suggest that quantitative muscle ultrasound has potential as a surrogate marker of disease progression in future interventional trials in CMT.

Mutation analysis of genes within the dynactin complex in a cohort of hereditary peripheral neuropathies.

The cytoplasmic dynein-dynactin genes are attractive candidates for neurodegenerative disorders given their functional role in retrograde transport along neurons. The cytoplasmic dynein heavy chain (DYNC1H1) gene has been implicated in various neurodegenerative disorders, and dynactin 1 (DCTN1) genes have been implicated in a wide spectrum of disorders including motor neuron disease, Parkinson's disease, spinobulbar muscular atrophy and hereditary spastic paraplegia. However, the involvement of other dynactin genes with inherited peripheral neuropathies (IPN) namely, hereditary sensory neuropathy, hereditary motor neuropathy and Charcot-Marie-Tooth disease is under reported. We screened eight genes; DCTN1-6 and ACTR1A and ACTR1B in 136 IPN patients using whole-exome sequencing and high-resolution melt (HRM) analysis. Eight non-synonymous variants (including one novel variant) and three synonymous variants were identified. Four variants have been reported previously in other studies, however segregation analysis within family members excluded them from causing IPN in these families. No variants of disease significance were identified in this study suggesting the dynactin genes are unlikely to be a common cause of IPNs. However, with the ease of querying gene variants from exome data, these genes remain worthwhile candidates to assess unsolved IPN families for variants that may affect the function of the proteins.

Transanal rectal resection: an initial experience of 20 cases.

AIM: Low anterior resection (LAR) can present a formidable surgical challenge, particularly for tumours located in the distal third of the rectum. Transanal total mesorectal excision (taTME) aims to overcome some of these difficulties. We report our initial experience with this technique. METHOD: From June 2013 to September 2014, 20 selected patients underwent transanal rectal resection for various malignant and benign low rectal pathologies. All patients with rectal cancer were discussed at a multidisciplinary team meeting. Data were entered into a prospective managed international database. RESULTS: Of the 20 patients (14 male), seventeen (85%) had rectal cancer lying at a median distance of 2 cm (range 0-7) from the anorectal junction. The operations performed included LAR (16). Abdominoperineal excision (2) and completion proctectomy (2), all of which were performed by a minimally invasive approach with three conversions. The mean operation time was 315.3 min. There were six postoperative complications of which two (10%) were Clavien-Dindo Grade IIIb (pelvic haematoma and a late contained anastomotic leakage). The median length of stay was 7 days. The TME specimen was intact in 94.1% of cancer cases. The mean number of harvested lymph nodes was 23.2. There was only one positive circumferential resection margin (tumour deposit; R1 rate 5.9%). One patient developed a distant recurrence (median follow-up 10 months, range 6-21). CONCLUSION: TaTME was safe in this small series of patients. It is especially attractive in patients with a narrow and irradiated pelvis and a tumour in the lower third of the rectum. TaTME is technically demanding, but the good outcomes should prompt randomized studies and prospective registration of all taTME cases in an international registry.

Laparoscopic rectopexy is feasible and safe in the emergency admission setting.

AIM: External rectal prolapse may require emergency admission in the elderly and comorbid population. We report the safety and efficacy of laparoscopic ventral rectopexy in patients having an emergency admission with external rectal prolapse. METHOD: A retrospective analysis was performed of a prospective database of all rectopexies performed from 2006. Outcome and follow-up data were assessed. RESULTS: Of 812 rectopexies performed, 28 were included for analysis. The mean length of hospital stay was 13.0 days. All operations were completed successfully and without intra-operative complications. Four patients developed a postoperative complication. Two patients developed a recurrence of prolapse. CONCLUSION: Laparoscopic correction of rectal prolapse following emergency admission is both feasible and safe. It can be considered for both recurring cases and cases with multiple comorbidities.

Augmenting the decision making process in acute appendicitis: A retrospective cohort study.

INTRODUCTION: Acute appendicitis is a common surgical diagnosis. We investigated the use of blood markers (WCC, CRP and serum bilirubin) and diagnostic imaging (USS and CT scan) to arrive at this diagnosis, as well as the surgical approach used for appendicectomy. METHODS: This was a retrospective analysis of consecutive patients undergoing appendicectomy in seven hospitals within GG&C Health Board during a 6 month study period. Data were collected from electronic patient records. Sensitivity and specificity of each investigation for diagnosing acute appendicitis was calculated. RESULTS: 363 patients were included. Appendicectomy was performed open in 53%, laparoscopically in 43% and converted in 4%. Diagnostic imaging was used in 38%. The overall negative appendicectomy rate was 15% (18% when no imaging was used, 23% when USS was used and 1% when CT scanning was used). Elevated bilirubin had a sensitivity of 0.44 and a specificity of 0.84 for detecting acute appendicitis. Sensitivity and specificity for elevated WCC were 0.78 and 0.55, and for elevated CRP were 0.81 and 0.59, respectively. The specificity of bilirubin for diagnosing perforated appendicitis was 0.63. DISCUSSION: WCC and CRP were sensitive blood markers in acute appendicitis, whereas serum bilirubin was more specific. Diagnostic imaging with a CT scan was very effective at reducing the rate of negative appendicectomy, but USS was not. CONCLUSION: Serum bilirubin has utility in diagnosing acute appendicitis, irrespective of whether perforation has occurred. CT scanning should be considered the first line imaging modality for investigation of acute appendicitis if diagnosis is in doubt.

A national trainee-led audit of inguinal hernia repair in Scotland.

PURPOSE: This audit assessed inguinal hernia surgery in Scotland and measured compliance with British Hernia Society Guidelines (2013), specifically regarding management of bilateral and recurrent inguinal hernias. It also assessed the feasibility of a national trainee-led audit, evaluated regional variations in practise and gauged operative exposure of trainees. METHODS: A prospective audit of adult inguinal hernia repairs across every region in Scotland (30 hospitals in 14 NHS boards) over 2-weeks was co-ordinated by the Scottish Surgical Research Group (SSRG). RESULTS: 235 patients (223 male, median age 61) were identified and 96 % of cases were elective. Anaesthesia was 91 % general, 5 % spinal and 3 % local. Prophylactic antibiotics were administered in 18 %. Laparoscopic repair was used in 33 % (30 % trainee-performed). Open repair was used in 67 % (42 % trainee-performed). Elective primary bilateral hernia repairs were laparoscopic in 97 % while guideline compliance for an elective recurrence was 77 %. For elective primary unilateral hernias, the use of laparoscopic repair varied significantly by region (South East 43 %, North 14 %, East 7 % and West 6 %, p < 0.001) as did repair under local anaesthesia for open cases (North 21 %, South East 4 %, West 2 % and East 0 %, p = 0.001). Trainees independently performed 9 % of procedures. There were no significant differences in trainee or unsupervised trainee operator rates between laparoscopic and open cases. Mean hospital stay was 0.7-days with day case surgery performed in 69 %. CONCLUSIONS: This trainee-lead audit provides a contemporary view of inguinal hernia surgery in Scotland. Increased compliance on recurrent cases appears indicated. National re-audit could ensure improved adherence and would be feasible through the SSRG.

Contribution of surgical specialization to improved colorectal cancer survival.

BACKGROUND: Reorganization of colorectal cancer services has led to surgery being increasingly, but not exclusively, delivered by specialist surgeons. Outcomes from colorectal cancer surgery have improved, but the exact determinants remain unclear. This study explored the determinants of outcome after colorectal cancer surgery over time. METHODS: Postoperative mortality (within 30 days of surgery) and 5-year relative survival rates for patients in the West of Scotland undergoing surgery for colorectal cancer between 1991 and 1994 were compared with rates for those having surgery between 2001 and 2004. RESULTS: The 1823 patients who had surgery in 2001-2004 were more likely to have had stage I or III tumours, and to have undergone surgery with curative intent than the 1715 patients operated on in 1991-1994. The proportion of patients presenting electively who received surgery by a specialist surgeon increased over time (from 14·9 to 72·8 per cent; P < 0·001). Postoperative mortality increased among patients treated by non-specialists over time (from 7·4 to 10·3 per cent; P = 0·026). Non-specialist surgery was associated with an increased risk of postoperative death (adjusted odds ratio 1·72, 95 per cent confidence interval (c.i.) 1·17 to 2·55; P = 0·006) compared with specialist surgery. The 5-year relative survival rate increased over time and was higher among those treated by specialist compared with non-specialist surgeons (62·1 versus 53·0 per cent; P < 0·001). Compared with the earlier period, the adjusted relative excess risk ratio for the later period was 0·69 (95 per cent c.i. 0·61 to 0·79; P < 0·001). Increased surgical specialization accounted for 18·9 per cent of the observed survival improvement. CONCLUSION: Increased surgical specialization contributed significantly to the observed improvement in longer-term survival following colorectal cancer surgery.

Quality of care in rectal cancer surgery. Exploring influencing factors in the West of Scotland.

AIM: To assess variability in the proportions of types of major resection for rectal cancer throughout the west of Scotland (WoS) and ascertain factors explaining the variability. METHOD: Retrospective cohort study of a regional population clinical audit database. This was linked to cancer registrations and death certificates in order that outcome analyses could be derived. Univariate and multivariate binary logistic regression analyses were used to explore determinants of survival. RESULTS: A total of 1574 patients met the inclusion criteria. The age range was from 22 to 97 years. The mean age was 67, median age 68 and the standard deviation was 11.5. The majority of patients (61%) were male. Unlike previous series, male patients and those with poorer socioeconomic circumstances (SEC) were no more likely to receive an abdominoperineal excision (APE) procedure for rectal cancer. CONCLUSION: Variation exists in the west of Scotland regarding surgical treatment for rectal cancer. We found no difference in the type of procedure offered according to sex, intent of operation or socioeconomic circumstances with reference to APE and anterior resection (AR) for rectal cancer. We conclude therefore that our region provides an equitable service on grounds of sex and SEC. This demonstrates that an equitable surgical service has been provided for those suffering from rectal cancer. Circumferential margin positivity was four times more likely in an APE than an AR for rectal cancer. This is not explained by age, stage, sex, socioeconomic circumstances (SEC), volume of surgery, intent of operation, type of admission or year of incidence.

Molecular genetics and mechanisms of disease in distal hereditary motor neuropathies: insights directing future genetic studies.

The distal hereditary motor neuropathies (dHMNs) are a clinically and genetically heterogeneous group of disorders that primarily affect motor neurons, without significant sensory involvement. New dHMN genes continue to be identified. There are now 11 causative genes described for dHMN, and an additional five genetic loci with unidentified genes. This genetic heterogeneity has further delineated the classification of dHMN, which was previously classified according to mode of inheritance, age at onset, and additional complicating features. Some overlap between phenotypically distinct forms of dHMN is also apparent. The mutated genes identified to-date in dHMN include HSPB1, HSPB8, HSPB3, DCTN1, GARS, PLEKHG5, BSCL2, SETX, IGHMBP2, ATP7A and TRPV4. The pathogenesis of mutations remains to be fully elucidated, however common pathogenic mechanisms are emerging. These include disruption of axonal transport, RNA processing defects, protein aggregation and inclusion body formation, disrupted calcium channel activity, and loss of neuroprotective signalling. Some of these dHMN genes are also mutated in Charcot-Marie-Tooth (CMT) disease and spinal muscular atrophy (SMA). This review examines the growing number of identified dHMN genes, discusses recent insights into the functions of these genes and possible pathogenic mechanisms, and looks at the increasing overlap between dHMN and the other neuropathies CMT2 and SMA.

Mechanical bowel preparation does not influence outcomes following colonic cancer resection.

BACKGROUND: Meta-analyses have indicated that preoperative mechanical bowel preparation (MBP) confers no clear benefit and may indeed be harmful for patients with colorectal cancer. The effects of bowel preparation on longer-term outcomes have not been reported. The aim was to compare long-term survival and surgical complications in patients who did or did not receive MBP before surgery for colonic cancer. METHODS: This was a retrospective cohort study of all patients undergoing potentially curative surgery for colonic cancer after routine hospital admission in the West of Scotland between January 2000 and December 2005. Clinical audit data were linked to cancer registrations and death certificates. Kaplan-Meier and Cox proportional hazards models were used to explore determinants of survival. RESULTS: A total of 1730 patients underwent potentially curative surgery for colonic cancer, of whom 886 (51·2 per cent) were men. The mean(s.d.) age was 69·7(10·6) years. Some 1460 patients (84·4 per cent) received MBP. Median follow-up was 3·5 (range 0·1-6·7) years. There were no statistically significant differences in 30-day postoperative complication rates between groups. The unadjusted hazard ratio (HR) for death from all causes for patients treated with MBP (versus no MBP) was 0·72 (95 per cent confidence interval 0·57 to 0·91). Multivariable analysis with adjustment for age, sex, socioeconomic circumstances, disease stage and presentation for surgery showed that MBP had no independent effect on all-cause mortality (HR 0·85, 0·67 to 1·10). CONCLUSION: Neither postoperative complications nor long-term survival are improved by MBP before colonic cancer surgery.

A retrospective review of X-linked Charcot-Marie-Tooth disease in childhood.

OBJECTIVE: X-linked Charcot-Marie-Tooth disease (CMTX) is infrequently diagnosed in childhood, and its clinical and neurophysiologic features are not well-described. We reviewed clinical, neurophysiologic, and pathologic findings in 17 children with CMTX. METHODS: This was a retrospective review of children with CMTX from 2 tertiary pediatric hospitals. The diagnosis of CMTX was based on an identifiable connexin 32 mutation (CMTX1) or a consistent pedigree and neurophysiologic features in children without a connexin 32 mutation (CMTX-other). RESULTS: Six boys and 2 girls from 8 kindreds had CMTX1, and 8 boys and 1 girl from 5 kindreds had other forms of CMTX (CMTX-other). Fifteen children, including males and carrier females, were symptomatic from infancy or early childhood (younger than 5 years). In addition to the typical Charcot-Marie-Tooth disease clinical phenotype, some patients had delayed motor development, sensorineural hearing loss, tremor, pathologic fractures, or transient CNS disturbances. Eleven children underwent nerve conduction studies. Median nerve motor nerve conduction velocities were in the intermediate to normal range (30-54 m/s) in all children older than 2 years. Axon loss, reflected by low-amplitude compound muscle action potentials, was present in all patients. A pattern of X-linked dominant inheritance, with carrier females showing an abnormal neurologic or neurophysiologic examination, correlated with the presence of a connexin 32 mutation in all but 2 pedigrees. CONCLUSIONS: The clinical phenotype of CMTX is broader than previously reported. Onset in males and carrier females is most often in early childhood. Families with an X-linked dominant inheritance pattern are likely to have CMTX1.

Cortical excitability in hereditary motor neuronopathy with pyramidal signs: comparison with ALS.

BACKGROUND: Distal hereditary motor neuronopathy with pyramidal features (dHMNP) is a hereditary neurodegenerative disorder characterised by the presence of upper and lower motor neuron signs. The pathophysiological mechanisms underlying these clinical findings remain elusive. Given that cortical hyperexcitability appears to underlie neurodegeneration in amyotrophic lateral sclerosis (ALS), a disorder that may clinically resemble dHMNP, the present study applied novel cortical excitability studies to further investigate the pathophysiological mechanisms in dHMNP. METHODS: Threshold tracking transcranial magnetic stimulation (TMS) studies were undertaken using a 90 mm circular coil. Peripheral nerve excitability was performed by stimulating the median nerve at the wrist, with recording made over the abductor pollicis brevis muscle. Studies were undertaken in six dHMNP and 52 ALS patients, and compared with 55 normal controls. RESULTS: Central motor conduction time (CMCT) was significantly prolonged in dHMNP (dHMNP 7.7 (SEM 0.7) ms; ALS 4.9 (0.3) ms; controls 5.1 (0.2) ms, p<0.01). Short interval intacortical inhibition (SICI) was significantly reduced in ALS patients (0.8 (0.8)%) when compared with dHMNP (6.4 (0.7)%, p<0.0001) and controls (8.6 (1.1)%, p<0.0001). Reduction in SICI was accompanied by significant increases in the magnetic stimulus-response curve gradient and intracortical facilitation, and reduction in cortical silent period duration in ALS, while all these parameters of cortical excitability were normal in dHMNP. CONCLUSIONS: The present study has established a prolonged CMCT and normal cortical excitability in dHMNP, thereby providing further support for the hypothesis that cortical hyperexcitability underlies neurodegeneration in ALS.

A novel TARDBP mutation in an Australian amyotrophic lateral sclerosis kindred.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder that causes loss of motor neurons. A pathological hallmark of ALS is the presence of ubiquitinated TAR DNA binding protein (TDP-43) inclusions in the cytoplasm of affected cells. Rare pathogenic mutations within the gene TARDBP that encode TDP-43 were recently reported in ALS but their functional consequences are unknown. To further investigate the pathogenic role of TDP-43 in ALS, a mutation analysis of TARDBP was performed in an Australian cohort of 74 sporadic and 30 familial ALS cases. A novel familial ALS mutation in TDP-43 was identified that substitutes a highly conserved residue (G294V) and is predicted to disrupt the glycine rich domain in the C terminus, a region that plays a role in RNA binding and is required for the exon skipping activity of TDP-43.

Severe early-onset axonal neuropathy with homozygous and compound heterozygous MFN2 mutations.

OBJECTIVE: Severe early-onset axonal neuropathy (SEOAN) is a heterogeneous phenotype first delineated by Ouvrier et al., characterized by progressive axonal degeneration with gait problems often progressing to wheelchair requirement and later respiratory involvement. Most cases are sporadic single cases. Some have heterozygous mitofusin 2 (MFN2) mutations, many of which are de novo dominant mutations. The aim of this study was to investigate the mode of inheritance in three individuals with severe early-onset axonal neuropathy and homozygous or compound heterozygous MFN2 mutations. METHODS: The clinical and molecular findings in the parents of three individuals with SEOAN with homozygous or compound heterozygous MFN2 mutations were examined. RESULTS: All parents were asymptomatic or mildly symptomatic with some signs of peripheral neuropathy indicating a minimal phenotype. Two had hearing problems. All parents carried the relevant single base (heterozygous) MFN2 variations. CONCLUSION: Severe early-onset axonal neuropathy due to MFN2 mutations can present as an apparently recessively inherited neuropathy but the minimal phenotype in the parents suggests a semi-dominant mechanism.

Proof of genetic heterogeneity in X-linked Charcot-Marie-Tooth disease.

OBJECTIVE: To characterize a large family with X-linked Charcot-Marie-Tooth (CMT) neuropathy without mutations in the gap junction protein B1 (GJB1) gene, which has an unusual phenotype that is different in some aspects from classic CMTX1. METHODS: We tested CMT families consistent with X-linked inheritance for GJB1 mutations. We compared the largest family (CMT623) without GJB1 mutation and with linkage excluding the CMTX1 locus to CMTX1 and normal individuals. RESULTS: Only 51% of probable X-linked CMT families had mutations in GJB1. Family CMT623 shows linkage to Xq26.3-q27.1 (lod score z = 6.58), a region within the previously identified locus for CMTX3, Xq26-q28. Unlike CMTX1, affected males in family CMT623 report pain and paraesthesia before the onset of sensory loss, and women are usually asymptomatic. As in CMTX1, affected males have widely ranging intermediate motor conduction velocities. The coding regions of 14 positional candidate genes within the narrowed CMTX3 locus have been excluded for a pathogenic role in the disease. CONCLUSION: This study is the first to confirm the CMTX3 locus and to refine the genetic interval to a 5.7-Mb region flanked by the markers DXS1041 and DXS8106. GJB1 mutation-negative forms of X-linked CMT, such as CMTX3, may account for a significant proportion of X-linked CMT.

Mild early onset axonal Charcot-Marie-Tooth disease not linked to other axonal Charcot-Marie-Tooth loci.

Autosomal dominant axonal Charcot-Marie-Tooth disease type 2 (CMT2) is a heterogeneous group of disorders with seven chromosomal loci mapped in the uncomplicated forms of CMT2. The authors report clinical, electrophysiologic, and genetic analysis of a Polish CMT2 family. Nine known CMT2 gene loci and one MPZ gene locus have been excluded. The authors' findings suggest that this family represents a novel form of CMT2 disease.

Evidence that a major site of expression of the RHO-GTPASE activating protein, oligophrenin-1, is peripheral myelin.

Oligophrenin-1 is a recently discovered Rho-GTPase activating protein, mutation of which is associated with X-linked mental retardation. Since little is known about the cellular localization of oligophrenin-1 in central and peripheral neurons, we investigated its expression by RT-PCR and immunochemical analysis. Oligophrenin-1 immunoreactivity was found in glial cells forming myelin sheaths in the vagus nerve, sciatic nerve and dorsal roots of guinea-pig, rat and human, in chromaffin cells of the adrenal medulla, and in chromaffin cells associated with sympathetic ganglia. No immunoreactivity was detected in sympathetic neurons, in glial cells surrounding these neurons, in optic nerve or in spinal cord myelin. The full length cDNA sequence was determined from guinea-pig sciatic nerve. The translated amino acid sequence was 99% identical to the published human oligophrenin-1 sequence. Western blotting revealed two protein forms which were expressed to different relative extents in different tissues. A 91 kDa form was predominant in extracts of sciatic nerve whereas a 36 kDa form was relatively more abundant in adrenal medulla and brain. Greater amounts of the full length oligophrenin-1 protein occurred in the sciatic nerve of adult rats, compared with P2 rats, which reflects the development of myelination. The presence of multiple forms does not appear to be due to alternative mRNA splicing since RT-PCR products amplified from a variety of tissues were identical and only a single mRNA transcript of 7.4 kb was identified by Northern analysis. These findings demonstrate that a major site of oligophrenin-1 expression is peripheral myelin.