Location of Retroperitoneal Lymph Node Metastases in Upper Tract Urothelial Carcinoma: Results from a Prospective Lymph Node Mapping Study

Background

There is limited information on the distribution of retroperitoneal lymph node metastases (LNMs) in upper tract urothelial carcinoma (UTUC).

Objective

To investigate the location of LNMs in UTUC of the renal pelvis or proximal ureter and short-term complications after radical nephroureterectomy (RNU) with lymph node dissection (LND).

Design setting and participants

This was a prospective Nordic multicenter study (four university hospitals, two county hospitals). Patients with clinically suspected locally advanced UTUC (stage >T1) and/or clinical lymph node-positive (cN+) disease were invited to participate. Participants underwent RNU and fractionated retroperitoneal LND using predefined side-specific templates.

Outcome measurements and statistical analysis

The location of LNMs in the LND specimen and retroperitoneal lymph node recurrences during follow-up was recorded. Postoperative complications within 90 d of surgery were ascertained from patient charts. Descriptive statistics were used.

Results and limitations

LNMs were present in the LND specimen in 23/100 patients, and nine of 100 patients experienced a retroperitoneal recurrence. Distribution per side revealed LNMs in the LND specimen in 11/38 (29%) patients with right-sided tumors, for whom the anatomically larger, right-sided template was used, in comparison to 12/62 (19%) patients with left-sided tumors, for whom a more limited template was used. High-grade complications (Clavien grade ≥3) within 90 d of surgery were registered for 13/100 patients. The study is limited in size and not powered to assess survival estimates.

Conclusions

The suggested templates that we prospectively applied for right-sided and left-sided LND in patients with advanced UTUC included the majority of LNMs. High-grade complications directly related to the LND part of the surgery were limited.

Patient summary

This study describes the location of lymph node metastases in patients with cancer in the upper urinary tract who underwent surgery to remove the affected kidney and ureter. The results show that most metastases occur within the template maps for lymph node surgery that we investigated, and that this surgery can be performed with few severe complications.

Urodrill - a novel MRI-guided endoscopic biopsy technique to sample and molecularly classify muscle-invasive bladder cancer without fractionating the specimen during transurethral resection

The current diagnostic pathway for patients with muscle-invasive bladder cancer (MIBC), which involves with computed tomography urography, cystoscopy, and transurethral resection of the bladder (TURB) to histologically confirm MIBC, delays definitive treatment. The Vesical Imaging-Reporting and Data System (VI-RADS) has been suggested for MIBC identification using magnetic resonance imaging (MRI), but a recent randomized trial reported misclassification in one-third of patients. We investigated a new endoscopic biopsy device (Urodrill) for histological confirmation of MIBC and assessment of molecular subtype by gene expression in patients with VI-RADS 4 and 5 lesions on MRI. In ten patients, Urodrill biopsies were guided by MR images to the muscle-invasive portion of the tumor via a flexible cystoscope under general anesthesia. During the same session, conventional TURB was subsequently performed. A Urodrill sample was successfully obtained in nine of ten patients. MIBC was verified in six of nine patients, and seven of nine samples contained detrusor muscle. In seven of eight patients for whom a Urodrill biopsy sample was subjected to RNA sequencing, single-sample molecular classification according to the Lund taxonomy was feasible. No complications related to the biopsy device occurred. A randomized trial comparing this new diagnostic pathway for patients with VI-RADS 4 and 5 lesions and the current standard (TURB) is warranted.

Patient summary

We report on a novel biopsy device for patients with muscle-invasive bladder cancer that facilitates histology analysis and molecular characterization of tumor samples.

Women's experience of sexuality after radical cystectomy - a qualitative study

PURPOSE

The aim of this study was to explore how women experienced sexuality after radical cystectomy due to bladder cancer.

METHODS

We performed an interview study with qualitative design with content analysis. Inclusion criteria were age below 75 years. In total 10 women, with a median age of 64 years at surgery, were interviewed at median 24 months post radical cystectomy.

RESULTS

The 10 women described sexual life as affected after surgery but they all tried to find ways to overcome the new situation together with their partner. The overall theme was 'A balance between emotional and physical closeness' emerged from 30 codes that were condensed into five subcategories and two categories: 'A sensual relationship' and 'A sexual relationship'. The first category constituted the subcategories 'Feeling of intimacy' and 'The importance of the relationship'. The category 'A sexual relationship' was revealed from the subcategories 'Reluctance to engage in sexual activity' and 'Partner inability to engage in sexual activity', and 'Acting for sexual rehabilitation'.

CONCLUSIONS

The uncertainty that the women felt about their anatomical changes after radical cystectomy created a sexual anxiety and reluctance to resume intercourse. Even though the surgery had a major impact on their sexual life, the women tried to be sexually active. However, the meaning of sexual life was not just having sexual activity but also included closeness, affirmation, affection, and feeling attractive. Sexual counseling at an appropriate timepoint is essential to assure a balance between emotional and physical closeness, i.e. to regain sexual health.

Robot-assisted nephroureterectomy for upper tract urothelial carcinoma-feasibility and complications: a single center experience

BACKGROUND

Robot-assisted nephroureterectomy (RANU) is the primary treatment for upper tract urothelial carcinoma (UTUC) at our hospital for patients with clinical stage less than T2, and for patients with invasive tumours, but unfit for major surgery.

OBJECTIVE

To assess peri-operative conditions and outcomes of RANU at our unit, and to evaluate the safety of the procedure.

METHODS

The medical records of all 166 patients undergoing RANU for suspected UTUC and followed for more than three months in a large university hospital in Sweden were reviewed retrospectively. After the exclusion of twenty patients because of previous cystectomy, simultaneous surgical procedure, or other tumour types than UTUC in the pathological report, 146 patients remained for the analyses. The primary endpoint was complication rate according to Clavien-Dindo at 90 days. Secondary endpoints were perioperative bleeding, violation of oncological surgical principles, hospital stay, and re-admission within 90 days.

RESULTS

The median age was 75 [(Inter Quartile Range) IQR 70-80] years and 57% of the patients had an ASA score above 2. According to Clavien-Dindo, one patient had a grade 3 complication, and no patient had a grade 4-5 complication. The median blood loss was 50 (IQR 20-100) ml and the median hospital stay was 6 (IQR 5-7) days. Twelve patients were re-admitted to the hospital within 90 days (eight with urinary tract infection/haematuria, one with hematoma, and three with other diseases).

CONCLUSION

Robot-assisted nephroureterectomy is a safe procedure for patients with upper tract urothelial carcinoma, with a low risk of major surgical complications.

Anorectal dysfunction after radical cystectomy for bladder cancer

Objective: To prospectively assess anorectal dysfunction using patient-reported outcomes using validated questionnaires, manovolumetry and endoanal ultrasound before and 12 months after RC.Patients and methods: From 2014 to 2019, we prospectively included 44 patients scheduled for RC. Preoperatively and 12 months after surgery, 41 patients filled in a low anterior resection syndrome score (LARS-score) to assess fecal incontinence, increased frequency, urgency and emptying difficulties and a St Mark's score to assess fecal incontinence in conjunction with manovolumetry and endoanal ultrasound examinations. Pre- and postoperative patient-reported anorectal dysfunction were assessed by LARS-score and St Marks's score. At the same time-points, anorectal function was evaluated by measuring mean anal resting and maximal squeeze pressures, volumes and pressures at first desire, urgency to defecate and maximum toleration during manovolumetry. Wilcoxon's signed rank test was used to compare pre- and postoperative outcomes by questionnaires.Results: Postoperatively 6/41 (15%) patients reported flatus incontinence assessed by the LARS-questionnaire, and correspondingly the St Mark's score increased postoperatively. The median anal resting pressure decreased from 57 mmHg preoperatively to 46 mmHg after RC, but without any postoperative anatomic defects detected by endoanal ultrasound. Volumes and pressures at first desire, urgency to defecate and maximum toleration during manovolumetry all increased after RC, indicating decreased postoperative rectal sensation, as rectal compliance was unaltered.Conclusions: Postoperative flatus incontinence is reported by one out of seven patients after RC, which corresponds to decreased anal resting pressures. The finding of decreased rectal sensation might also contribute to patient-reported symptoms and anorectal dysfunction after RC.

Urostomal ileal conduit complications in association with abdominal wall mesh implantation

OBJECTIVE

Parastomal hernia (PH) in association with an ileal conduit is a common complication that is difficult to treat. Mesh reinforcement has been suggested to improve outcomes; either as prophylaxis or for treatment of a parastomal hernia during abdominal wall reconstruction.

PATIENTS AND METHODS

A retrospective study was performed in consecutive patients subjected to mesh implantation between 2000 and 2016 having a concurrent or previous ileal conduit reconstruction. Postoperative and late urostomal complications, as well as hernia occurrence, were ascertained by a chart review of patients' records.

RESULTS

A total of 25 patients were included of whom 13 (52%) developed either a urostomal complication, a PH, or both. Complications were caused by mesh erosion in four patients, of which three were diagnosed more than five years after surgery. Four patients developed a urostomal stenosis. One out of eight patients with urostomal complications were subjected to a new ileal conduit reconstruction and another four to other types of revisional surgery.

CONCLUSIONS

Every second patient with an ileal conduit developed either a local urostomal complication, a PH, or both after abdominal wall mesh reconstruction. A careful and cautious attitude towards the use of mesh in patients with an ileal conduit is suggested.

Using the Movember Foundation's GAP3 cohort to measure the effect of active surveillance on patient-reported urinary and sexual function-a retrospective study in low-risk prostate cancer patients

BACKGROUND

Active surveillance (AS) for low-risk prostate cancer (PCa) is intended to overcome potential side-effects of definitive treatment. Frequent prostate biopsies during AS may, however, impact erectile (EF) and urinary function (UF). The objective of this study was to test the influence of prostate biopsies on patient-reported EF and UF using multicenter data from the largest to-date AS-database.

METHODS

In this retrospective study, data analyses were performed using the Movember GAP3 database (v3.2), containing data from 21,169 AS participants from 27 AS-cohorts worldwide. Participants were included in the study if they had at least one follow-up prostate biopsy and completed at least one patient reported outcome measure (PROM) related to EF [Sexual Health Inventory for Men (SHIM)/five item International Index of Erectile Function (IIEF-5)] or UF [International Prostate Symptom Score (IPSS)] during follow-up. The longitudinal effect of the number of biopsies on either SHIM/IIEF-5 or IPSS were analyzed using linear mixed models to adjust for clustering at patient-level. Analyses were stratified by center; covariates included age and Gleason Grade group at diagnosis, and time on AS.

RESULTS

A total of 696 participants completed the SHIM/IIEF-5 3,175 times, with a median follow-up of 36 months [interquartile range (IQR) 20-55 months]. A total of 845 participants completed the IPSS 4,061 times, with a median follow-up of 35 months (IQR 19-56 months). The intraclass correlation (ICC) was 0.74 for the SHIM/IIEF-5 and 0.68 for the IPSS, indicating substantial differences between participants' PROMs. Limited heterogeneity between cohorts in the estimated effect of the number of biopsies on either PROM were observed. A significant association was observed between the number of biopsies and the SHIM/IIEF-5 score, but not for the IPSS score. Every biopsy was associated with a decrease in the SHIM/IIEF-5 score of an average 0.67 (95% CI, 0.47-0.88) points.

CONCLUSIONS

Repeated prostate biopsy as part of an AS protocol for men with low-risk PCa does not have a significant association with self-reported UF but does impact self-reported sexual function. Further research is, however, needed to understand whether the effect on sexual function implies a negative clinical impact on their quality of life and is meaningful from a patient's perspective. In the meantime, clinicians and patients should anticipate a potential decline in erectile function and hence consider incorporating the risk of this harm into their discussion about opting for AS and also when deciding on the stringency of follow-up biopsy schedules with long-term AS.

A first step towards a global nomogram to predict disease progression for men on active surveillance

BACKGROUND

Signs of disease progression (28%) and conversion to active treatment without evidence of disease progression (13%) are the main reasons for discontinuation of active surveillance (AS) in men with localised prostate cancer (PCa). We aimed to develop a nomogram to predict disease progression in these patients.

METHODS

As a first step in the development of a nomogram, using data from Movembers' GAP3 Consortium (n=14,380), we assessed heterogeneity between centres in terms of risk of disease progression. We started with assessment of baseline hazards for disease progression based on grouping of centres according to follow-up protocols [high: yearly; intermediate: ~2 yearly; and low: at year 1, 4 & 7 (i.e., PRIAS)]. We conducted cause-specific random effect Cox proportional hazards regression to estimate risk of disease progression by centre in each group.

RESULTS

Disease progression rates varied substantially between centres [median hazard ratio (MHR): 2.5]. After adjustment for various clinical factors (age, year of diagnosis, Gleason grade group, number of positive cores and PSA), substantial heterogeneity in disease progression remained between centres.

CONCLUSIONS

When combining worldwide data on AS, we noted unexplained differences of disease progression rate even after adjustment for various clinical factors. This suggests that when developing a global nomogram, local adjustments for differences in risk of disease progression and competing outcomes such as conversion to active treatment need to be considered.

Preventing Parastomal Hernia After Ileal Conduit by the Use of a Prophylactic Mesh: A Randomised Study

BACKGROUND

Parastomal hernia (PSH) after urinary diversion with ileal conduit is frequently a clinical problem.

OBJECTIVE

To investigate whether a prophylactic lightweight mesh in the sublay position can reduce the cumulative incidence of PSH after open cystectomy with ileal conduit.

DESIGN, SETTING, AND PARTICIPANTS

From 2012 to 2017, we randomised 242 patients 1:1 to conventional stoma construction (n = 124) or prophylactic mesh (n = 118) at three Swedish hospitals (ISRCTN 95093825).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was clinical PSH, and secondary endpoints were radiological PSH assessed in prone position with the stoma in the centre of a ring, parastomal bulging, and complications from the mesh.

RESULTS AND LIMITATIONS

Within 24 mo, 20/89 (23%) patients in the control arm and 10/92 (11%) in the intervention arm had developed a clinical PSH (p = 0.06) after a median follow-up of 3 yr, corresponding to a hazard ratio of 0.45 (confidence interval 0.24-0.86, p = 0.02) in the intervention arm. The proportions of radiological PSHs within 24 mo were 22/89 (25%) and 17/92 (19%) in the two study arms. During follow-up, five patients in the control arm and two in the intervention arm were operated for PSH. The median operating time was 50 min longer in patients receiving a mesh. No differences were noted in proportions of Clavien-Dindo complications at 90 d postoperatively or in complications related to the mesh during follow-up.

CONCLUSIONS

Prophylactic implantation of a lightweight mesh in the sublay position decreases the risk of PSH when constructing an ileal conduit without increasing the risk of complications related to the mesh. The median surgical time is prolonged by mesh implantation.

PATIENT SUMMARY

In this randomised report, we looked at the risk of parastomal hernia after cystectomy and urinary diversion with ileal conduit with or without the use of a prophylactic mesh. We conclude that such a prophylactic measure decreased the occurrence of parastomal hernias, with only a slight increase in operating time and no added risk of complications related to the mesh.

A registry-based study evaluating overall survival and treatment duration in Swedish patients with metastatic castration-resistant prostate cancer treated with enzalutamide

Objective: This retrospective, single-centre, non-interventional, registry-based study evaluated patients with metastatic castration-resistant prostate cancer (mCRPC) treated with enzalutamide in daily clinical practice at Skåne University Hospital, Malmö, Sweden.Materials and methods: Registry data were reviewed for patients treated with enzalutamide pre- or post-chemotherapy initiated between December 2013 and June 2017. The primary endpoint was overall survival (OS) in post-chemotherapy patients. Secondary endpoints were enzalutamide treatment duration in the pre- and post-chemotherapy setting. This study was approved by the Lund regional Ethics Review Board (Dnr:2017/716) and is registered with ClinicalTrials.gov (NCT03328364).Results: A total of 102 pre-chemotherapy and 98 post-chemotherapy patients were included. Median age was higher in the pre- than in the post-chemotherapy group (77 vs 72 years, respectively). Median OS in post-chemotherapy patients from initiation of enzalutamide until death from any cause was 14.3 months [95% confidence interval (CI) = 11.00-18.20]. Median treatment duration was 13.8 months (95% CI = 11.4-20.2) and 7.6 months (95% CI = 6.3-10.2) for pre- and post-chemotherapy patients, respectively.Conclusion: Enzalutamide can be used to effectively treat mCRPC patients in daily clinical settings, despite the patients being older and less healthy than those enrolled in the previous randomised, clinical registration studies.

Who should record surgical complications? Results from a third-party assessment of complications after radical cystectomy

Objective: In Sweden complications after radical cystectomy have been reported to the nationwide population-based Swedish Cystectomy Registry since 2011. Here, validation of the reporting was assessed in two healthcare regions.Materials and methods: Complications were ascertained from patient records by a third party not involved in the care delivered to 429 randomly selected patients from 949 who had undergone radical cystectomy since 2011 in four hospitals. Without knowledge of the outcome in the primary registration, post-operative complications within 90 days post-operatively were assessed by an independent review of patient charts, and the results were compared with the primary reports in the Swedish Cystectomy Registry.Results: The third-party assessment identified post-operative complications in 310 patients (72%). Low-grade complications (Clavien-Dindo I-II) were noted in 110 (26%) of the patients in the primary registration, but increased to 182 (42%) in the validation (p < 0.00001). High-grade complications (Clavien-Dindo III-V) were reported in 113 (26%) patients in the primary registration, but in 128 (30%) of the patients in the validation (p = 0.02). According to the third-party assessment, 18 patients (4%) had Clavien-Dindo grade IV complications and 12 (3%) died within 90 days of surgery (Clavien-Dindo grade V); corresponding values in the primary registration were 15 (3%) and 9 (2%), respectively. The readmission rate within 90 days increased from 27 to 32% in the validation (p < 0.00001).Conclusions: Compared with registry data, third-party assessment revealed more complications and readmissions after radical cystectomy. Hence such evaluation may improve the validity of reported complication data.

Consistent Biopsy Quality and Gleason Grading Within the Global Active Surveillance Global Action Plan 3 Initiative: A Prerequisite for Future Studies

Within the Movember Foundation's Global Action Plan Prostate Cancer Active Surveillance (GAP3) initiative, 25 centers across the globe collaborate to standardize active surveillance (AS) protocols for men with low-risk prostate cancer (PCa). A centralized PCa AS database, comprising data of more than 15000 patients worldwide, was created. Comparability of the histopathology between the different cohorts was assessed by a centralized pathology review of 445 biopsies from 15 GAP3 centers. Grade group 1 (Gleason score 6) in 85% and grade group ≥2 (Gleason score ≥7) in 15% showed 89% concordance at review with moderate agreement (κ=0.56). Average biopsy core length was similar among the analyzed cohorts. Recently established highly adverse pathologies, including cribriform and/or intraductal carcinoma, were observed in 3.6% of the reviewed biopsies. In conclusion, the centralized pathology review of 445 biopsies revealed comparable histopathology among the 15 GAP3 centers with a low frequency of high-risk features. This enables further data analyses-without correction-toward uniform global AS guidelines for men with low-risk PCa. PATIENT SUMMARY: Movember Foundation's Global Action Plan Prostate Cancer Active Surveillance (GAP3) initiative combines data from 15000 men with low-risk prostate cancer (PCa) across the globe to standardize active surveillance protocols. Histopathology review confirmed that the histopathology was consistent with low-risk PCa in most men and comparable between different centers.

Adjuvant radiotherapy of women with breast cancer - information, support and side-effects

The aim of this study was to 1) examine the occurrence and burden of side effects over time in the period after post surgical adjuvant radiotherapy in women with breast cancer and 2) explore the women's experiences of given information and need of support to handle side effects.

MATERIAL AND METHOD

171 women with breast cancer receiving post-surgical adjuvant radiotherapy completed a questionnaire on radiotherapy-related side effects (Treatment Toxicity Assessment Tool OTTAT) at four times between the start of radiotherapy and six months after completion. Comparisons were made between women with breast conservative surgery (group A) and women with modified mastectomy (group B), and for having chemotherapy or not (C+ and C-). Questions regarding the experience of delivered information and support were added.

RESULTS

Fatigue was the single most prevalent side effect and, together with skin reactions and pain, it also had the highest mean score over the study period and the largest score increase during treatment. The largest increase during the six months was seen for skin reaction, pain, and dyspnoea. The average score for skin reaction was significantly higher in group B than in group A. A majority of the women experienced the given information and support as satisfying and a need for follow-up of the side-effects was expressed.

CONCLUSION

Nursing for women with breast cancer receiving adjuvant radiotherapy should focus on preventing and treating side effects, and also include the period post treatment. There is a need for developing evidence based guidelines including guidelines for follow-up.

Novel Twinkle gene mutation in autosomal dominant progressive external ophthalmoplegia and multisystem failure

A Saudi Arabian family presented with adult onset autosomal dominant progressive external ophthalmoplegia (adPEO) complicated by late onset reversible failure of the CNS, respiratory, hepatic, and endocrine systems. Clinical findings were suggestive of mitochondrial dysfunction and multiple mitochondrial DNA deletions were demonstrated on long range and real time polymerase chain reaction assays but not on Southern blotting. The disorder is caused by a novel heterozygous PEO1 mutation predicting a Leu360Gly substitution in the twinkle protein. The peculiar clinical presentation expands the variable phenotype observed in adPEO and Twinkle gene mutations.

Charcot-Marie-Tooth disease: a clinico-genetic confrontation

Charcot-Marie-Tooth disease (CMT) is the most common neuromuscular disorder. It represents a group of clinically and genetically heterogeneous inherited neuropathies. Here, we review the results of molecular genetic investigations and the clinical and neurophysiological features of the different CMT subtypes. The products of genes associated with CMT phenotypes are important for the neuronal structure maintenance, axonal transport, nerve signal transduction and functions related to the cellular integrity. Identifying the molecular basis of CMT and studying the relevant genes and their functions is important to understand the pathophysiological mechanisms of these neurodegenerative disorders, and the processes involved in the normal development and function of the peripheral nervous system. The results of molecular genetic investigations have impact on the appropriate diagnosis, genetic counselling and possible new therapeutic options for CMT patients.

Charcot-Marie-Tooth disease: a clinico-genetic confrontation

Charcot-Marie-Tooth disease (CMT) is the most common neuromuscular disorder. It represents a group of clinically and genetically heterogeneous inherited neuropathies. Here, we review the results of molecular genetic investigations and the clinical and neurophysiological features of the different CMT subtypes. The products of genes associated with CMT phenotypes are important for the neuronal structure maintenance, axonal transport, nerve signal transduction and functions related to the cellular integrity. Identifying the molecular basis of CMT and studying the relevant genes and their functions is important to understand the pathophysiological mechanisms of these neurodegenerative disorders, and the processes involved in the normal development and function of the peripheral nervous system. The results of molecular genetic investigations have impact on the appropriate diagnosis, genetic counselling and possible new therapeutic options for CMT patients.

Spastin gene mutations in Bulgarian patients with hereditary spastic paraplegia

Hereditary spastic paraplegia (HSP) is an extremely heterogeneous group of neurodegenerative disorders affecting the longest axons in the central nervous system. The most common genetic form accounting for about 40% of the autosomal-dominant HSP (ADHSP) cases is spastin gene, SPG4. We performed mutation screening of the spastin gene on 36 unrelated HSP patients from three different ethnic groups (Bulgarian, Turks and Gypsies) and found four new mutations and one already reported. The phenotype-genotype correlations in Bulgarian SPG4 patients showed a great difference in the age at disease onset between patients with missense mutations and those harboring deletions and splice-site mutations. Our study is the first to present corroborative clinical data in favor of the general hypothesis that the clinical course of the disease is related to the type of the spastin mutation. The clinical and genealogical findings in Bulgarian SPG4 patients suggest that a positive family history for inheritance as an autosomal-dominant trait is a strong indication for spastin mutation screening.

POLG mutations in neurodegenerative disorders with ataxia but no muscle involvement

OBJECTIVE

To identify POLG mutations in patients with sensory ataxia and CNS features.

METHODS

The authors characterized clinical, laboratory, and molecular genetic features in eight patients from five European families. The authors conducted sequencing of coding exons of POLG, C10orf2 (Twinkle), and ANT1 and analyzed muscle mitochondrial DNA (mtDNA), including Southern blot analysis and long-range PCR.

RESULTS

Ataxia occurred in combination with various CNS features, including myoclonus, epilepsy, cognitive decline, nystagmus, dysarthria, thalamic and cerebellar white matter lesions on MRI, and neuronal loss in discrete gray nuclei on autopsy. Gastrointestinal dysmotility, weight loss, cardiomyopathy, and valproate-induced hepatotoxicity occurred less frequently. Two patients died without preceding signs of progressive external ophthalmoplegia. In muscle, typical findings of mitochondrial disease, such as ragged red fibers and Southern blot mtDNA abnormalities, were absent. POLG mutations were present in eight patients, including two isolated cases, and one Finnish and two unrelated Belgian families contained in total six patients. All POLG mutations were recessive, occurring in a homozygous state in seven patients and in a compound heterozygous state in one patient. The novel W748S mutation was identified in five patients from three unrelated families.

CONCLUSIONS

The clinical spectrum of recessive POLG mutations is expanded by sensory ataxic neuropathy, combined with variable features of involvement of CNS and other organs. Progressive external ophthalmoplegia, myopathy, ragged red fibers, and Southern blot abnormalities of muscle mitochondrial DNA also are not mandatory features associated with POLG mutations.

Charcot-Marie-Tooth disease with giant axons: a clinicopathological and genetic entity

The authors report an Italian family with autosomal-dominant Charcot-Marie-Tooth disease (CMT) in which there were giant axons in the sural nerve biopsy. Linkage to the known CMT2 loci (CMT2A, CMT2B, CMT2D, CMT2F) and mutations in the known CMT2 genes (Cx32, MPZ, NEFL), GAN, NEFM, and CMT1A duplication/HNPP deletion were excluded. This family with CMT and giant axons has a pathologic and genetic entity distinct from classic CMT.

Symmetry of two-terminal nonlinear electric conduction

The well-established symmetry relations for linear transport phenomena cannot, in general, be applied in the nonlinear regime. Here we propose a set of symmetry relations with respect to bias voltage and magnetic field for the nonlinear conductance of two-terminal electric conductors. We experimentally confirm these relations using phase-coherent, semiconductor quantum dots.

Patient homozygous for a recessive POLG mutation presents with features of MERRF

Both dominant and recessive missense mutations were recently reported in the gene encoding the mitochondrial DNA polymerase gamma (POLG) in patients with progressive external ophthalmoplegia (PEO). The authors report on a patient homozygous for a recessive missense mutation in POLG who presented with a multisystem disorder without PEO. The most prominent features were myoclonus, seizure, and sensory ataxic neuropathy, so the clinical picture overlapped with the syndrome of myoclonus, epilepsy, and ragged red fibers (MERRF).

A deletion in SCN1B is associated with febrile seizures and early-onset absence epilepsy

Generalized epilepsy with febrile seizures plus (GEFS+) is a clinically and genetically heterogeneous syndrome with childhood onset, characterized by febrile seizures (FS) and a variety of afebrile epileptic seizure types. The authors performed a mutational analysis of SCN1B on 74 unrelated probands with GEFS+, FS, or FS plus (FS+). In a family with FS+ and early-onset absence epilepsy, a mutation was identified that predicts a deletion of five amino acids in the extracellular immunoglobulin-like domain of SCN1B and potential loss of function. SCN1B mutations are associated with GEFS+ and may have a role in the elicitation of absence seizures.

Recessive POLG mutations presenting with sensory and ataxic neuropathy in compound heterozygote patients with progressive external ophthalmoplegia

Autosomal recessive progressive external ophthalmoplegia is a mitochondrial disease characterized by accumulation of multiple large-scale deletions of mitochondrial DNA. We previously reported missense mutations in POLG, the gene encoding the mitochondrial DNA polymerase gamma in two nuclear families compatible with autosomal recessive progressive external ophthalmoplegia. Here, we report a novel POLG missense mutation (R627W) in a sporadic patient and we provide genetic support that all these POLG mutations are actually causal and recessive. The novel patient presented with sensory ataxic neuropathy and has the clinical triad of sensory ataxic neuropathy, dysarthria and ophthalmoparesis (SANDO). This is the first finding of a genetic cause of Sensory Ataxic Neuropathy, Dysarthria and Ophthalmoparesis and it implies that this disorder may actually be a variant of autosomal recessive progressive external ophthalmoplegia. Sensory neuropathy is the initial feature in Belgian compound heterozygote autosomal recessive progressive external ophthalmoplegia patients, all carrying the POLG A467T mutation, which occurs at a frequency of 0.6% in the Belgian population.

[Hereditary neuropathy with liability to pressure palsies: study of six Spanish families]

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant inherited demyelinating neuropathy typically characterized by recurrent episodes of acute painless peripheral nerve palsies often preceded by minor trauma or compression at entrapment sites. However, less classical phenotypes have been reported. A 1.5 Mb deletion in chromosome 17 p11.2 has been shown to be the genetic basis of the disease in the majority of HNPP patients. The few families without this deletion harbored a mutation in the PMP22 gene. We performed a clinical, neurophysiological and molecular genetic study of 6 Spanish HNPP families. Five families (22 individuals) showed the classical chromosome 17 p11.2 deletion and one family (3 individuals) had a novel 3'splice-site mutation in PMP22. Neurophysiological abnormalities were detected in all symptomatic (n=21) and asymptomatic (n=4) deletion or mutation carriers, even in childhood. In addition to the typical presentation we observed other phenotypes: recurrent focal short-term sensory symptoms, a progressive mononeuropathy, a Charcot-Marie-Tooth (CMT) disease-like chronic progressive polyneuropathy, a chronic sensory polyneuropathy and a chronic inflammatory demyelinating polyneuropathy. We report new or very rare phenotypesThese atypical clinical aspects and intrafamilial heterogeneity are present in families with the HNPP deletion as well as in the family with the PMP22 mutation. However, the CMT disease-like chronic polyneuropathy was more common in the PMP22 mutation family. Intrafamilial heterogeneity also seemed to be more pronounced in this kinship. Patients in this family had a mild chronic motor and sensory polyneuropathy neurophysiologically characterized by delayed distal latencies, reduced nerve conduction velocities (NCV) within the demyelinating range, mildly decreased amplitudes of motor and sensory evoked potentials and absence of conduction blocks. In contrast, patients with the common HNPP deletion, regardless of their phenotype, had a diffuse increase in distal motor latencies contrasting with moderately reduced motor NCVs, preserved sensory nerve action potentials, slowing of NCVs at the common entrapment sites and occasionally conduction blocks. In this study we confirm the clinical and molecular heterogeneity of HNPP, emphasizing the need for a mutation analysis of the PMP22 gene when the common 17p11.2 deletion is not found in clinically suspected HNPP patients. We conclude that the 3'splice-site mutation in PMP22 and the common HNPP deletion have largely the same functional consequences although some clinical and neurophysiological differences were observed.

Cerebral amyloid angiopathy is a pathogenic lesion in Alzheimer's disease due to a novel presenilin 1 mutation

The dense-cored plaques are considered the pathogenic type of amyloid deposition in Alzheimer's disease brains because of their predominant association with dystrophic neurites. Nevertheless, in > 90% of cases of Alzheimer's disease amyloid is also deposited in cerebral blood vessel walls (congophilic amyloid angiopathy; CAA) but its role in Alzheimer's disease pathogenesis remains enigmatic. Here, we report a family (family GB) in which early-onset Alzheimer's disease was caused by a novel presenilin 1 mutation (L282V). This was unusually severe CAA reminiscent of the Flemish amyloid precursor protein (A692G) mutation we reported previously, which causes Alzheimer's disease and/or cerebral haemorrhages. In family GB, however, the disease presented as typical progressive Alzheimer's disease in the absence of strokes or stroke-like episodes. Similarly, neuroimaging studies and neuropathological examination favoured a degenerative over a vascular dementia. Interestingly, an immunohistochemical study revealed that, similar to causing dense-cored amyloid plaques, CAA also appeared capable of instigating a strong local dystrophic and inflammatory reaction. This was suggested by the observed neuronal loss, the presence of tau- and ubiquitin-positive neurites, micro- and astrogliosis, and complement activation. Together, these data suggest that, like the dense-cored neuritic plaques, CAA might represent a pathogenic lesion that contributes significantly to the progressive neurodegeneration that occurs in Alzheimer's disease.

Infantile demyelinating neuropathy associated with a de novo point mutation on Ser72 in PMP22 and basal lamina onion bulbs in skin biopsy

Codon 72 has been designated as a hot spot for distinct missense mutations in the peripheral myelin protein 22 (PMP22) gene. Ser72Leu substitution was associated with Dejerine-Sottas syndrome (DSS) in four patients and with congenital hypomyelination neuropathy (CHN) in one patient. Our objective was to report one other DSS patient with Ser72Leu substitution in PMP22 and to concurrently illustrate how less invasive procedures such as skin biopsy could provide a rapid and reliable alternative to conventional sural nerve biopsy for the characterization of histophenotypic features. A skin biopsy was carried out in a 2 4/12-year-old girl with muscle atrophy, hypotonia and weakness, as well as generalized areflexia and absent sensory and motor nerve responses. Standard electron microscope techniques were used. PMP22 was screened by automated direct nucleotide sequencing analysis. Morphological examination revealed basal lamina onion bulbs surrounding a de- or hypomyelinated axon in all nerve bundles. Mutation analysis demonstrated a missense point mutation in codon 72 of the PMP22 gene leading to a Ser72Leu substitution. Further genotype-phenotype correlations will have to determine whether morphologically distinct phenotypes can be correlated with specific mutations. For this purpose, cutaneous nerve bundles could serve as an alternative tool to help identify and classify subtypes in this heterogeneous syndrome.

Mutation of POLG is associated with progressive external ophthalmoplegia characterized by mtDNA deletions

Progressive external ophthalmoplegias (PEO) characterized by accumulation of large-scale mitochondrial DNA (mtDNA) deletions are rare human diseases. We mapped a new locus for dominant PEO at 15q22-q26 in a Belgian pedigree and identified a heterozygous mutation (Y955C) in the polymerase motif B of the mtDNA polymerase gamma (POLG). We identified three additional POLG missense mutations compatible with recessive PEO In two nuclear families. POLG is the only DNA polymerase responsible for mtDNA replication.

A novel 3′-splice site mutation in peripheral myelin protein 22 causing hereditary neuropathy with liability to pressure palsies

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant, demyelinating peripheral neuropathy. Clinical hallmarks are recurrent painless focal neuropathies mostly preceded by minor trauma or compression at entrapment sites of peripheral nerves. In the majority of the patients, HNPP is caused by a 1.5 Mb deletion on chromosome 17p11.2-p12 containing the peripheral myelin protein 22 (PMP22) gene. Point mutations within this gene are reported in only a few families. We report a novel mutation in the PMP22 gene in a Spanish family with HNPP. The mutation is a 3' splice-site mutation, preceding coding exon 3 (c.179-1 G>C), causing a mild HNPP phenotype.

CTLA-4-/- mice display T cell-apoptosis resistance resembling that ascribed to autoimmune-prone non-obese diabetic (NOD) mice

The genes conferring susceptibility to autoimmune (insulin-dependent) diabetes mellitus (IDDM) are, in most cases, not defined. Among the loci so far identified as associated with murine IDDM (Idd1-19), only the nature of Idd1 has been assessed. Here we show that thymocytes and peripheral lymphocytes of the non-obese diabetic (NOD) mouse are relatively resistant to apoptosis induced by gamma-irradiation. By linkage analysis of F2 progeny mice, we map this trait to a locus on chromosome 1 containing the Idd5 diabetes susceptibility region. By the use of congenic mice, we confirm the linkage data and map this locus to a 6 cM region on proximal chromosome 1. Ctla4, being localized in this chromosomal region and mediating crucial functions in T cell biology, is a logical candidate gene in the Idd5 susceptibility region. In line with this, we demonstrate that T cells from Ctla4(-/-)deficient mice show a similar resistance to gamma-irradiation-induced apoptosis as observed in the NOD mice. This reinforces the notion that CTLA-4 contributes to the pathogenesis of autoimmune diabetes.

Nonfibrillar diffuse amyloid deposition due to a gamma(42)-secretase site mutation points to an essential role for N-truncated A beta(42) in Alzheimer's disease

Amyloidogenic processing of the amyloid precursor protein (APP) with deposition in brain of the 42 amino acid long amyloid beta-peptide (A beta(42)) is considered central to Alzheimer's disease (AD) pathology. However, it is generally believed that nonfibrillar pre-amyloid A beta(42) deposits have to mature in the presence of A beta(40) into fibrillar amyloid plaques to cause neurodegeneration. Here, we describe an aggressive form of AD caused by a novel missense mutation in APP (T714I) directly involving gamma-secretase cleavages of APP. The mutation had the most drastic effect on A beta(42)/A beta(40) ratio in vitro of approximately 11-fold, simultaneously increasing A beta(42) and decreasing A beta(40) secretion, as measured by matrix-assisted laser disorption ionization time-of-flight mass spectrometry. This coincided in brain with deposition of abundant and predominant nonfibrillar pre-amyloid plaques composed primarily of N-truncated A beta(42) in complete absence of A beta(40). These data indicate that N-truncated A beta(42) as diffuse nonfibrillar plaques has an essential but undermined role in AD pathology. Importantly, inhibiting secretion of full-length A beta(42 )by therapeutic targeting of APP processing should not result in secretion of an equally toxic N-truncated A beta(42).

PMP22 Thr118Met is not a clinically relevant CMT1 marker

It is controversial if peripheral myelin protein 22 gene (PMP22) Thr118Met represents a functionally irrelevant polymorphism or, since hemizygosity for this variant has been found in two patients with Charcot-Marie-Tooth disease type 1 (CMT1 patients), it can act as a recessive CMT1 mutation. To shed further light on this variant and its diagnostic value we searched for carriers in 1018 individuals from the German general population, in 104 probands with hereditary neuropathy with liability to pressure palsies (HNPP) who were carriers of the 1.5-Mb deletion frequently associated with this disorder, in 187 patients with the 1.5-Mb duplication, and in 22 patients with a CMT1 phenotype who did not have any detectable anomaly in the PMP22 gene. Using allele-specific PCR we identified 14 [allele frequency (AF)=0.007] in the German general population, one (AF=0.01) in the HNPP group and six (AF=0.016) and two (AF=0.05) carriers of the PMP22 Thr118Met mutation in the CMT1 groups with and without gene defect. Carriers from all groups showed nerve conduction velocities which did not differ from typical values for these groups. We conclude that the hemizygous occurrence of the 118Met allele does not usually cause CMT1. Because of previous reports on its association with disease, and because its allele product shows abnormalities in in vitro expression systems, it seems possible that this mutation, together with yet unidentified factors, predisposes to CMT1. Alternatively, previously reported disease associations occurred by chance, and the 118Met allele causes biochemical abnormalities irrelevant for CMT1 formation. In either case this mutation is not a clinically relevant disease marker.

Associations of leptin with body fat distribution and metabolic parameters in non-insulin-dependent diabetic patients: no effect of apolipoprotein E polymorphism

Leptin levels have been shown previously to be associated with anthropometric parameters such as the body mass index (BMI), total body fat, and subcutaneous fat. Since apolipoprotein E (apoE) polymorphism is known to be a genetic marker affecting the relationship between certain anthropometric and metabolic parameters, we evaluated whether the leptin level and/or associations between the leptin level and body composition in non-insulin-dependent diabetic patients could be determined by apoE polymorphism. In 171 type 2 diabetic patients (105 male and 66 female), body composition (BMI, waist to hip ratio [WHR], fat mass, and visceral fat) was measured and fasting blood samples were obtained to determine the apoE genotype, leptin, glucose, and insulin levels, and the lipid profile. The mean leptin level for the whole group was 11.7 +/- 9.3 ng/mL, with a significant difference (P < .001) between men (7.1 +/- 4.9 ng/mL) and women (19.0 +/- 10.1 ng/mL). No difference was found for leptin levels or anthropometric variables between the 3 different apoE genotypes (E3/E3 homozygotes, E2 carriers, and E4 carriers). Only low-density lipoprotein (LDL) cholesterol was significantly different between the 3 apoE subgroups. The correlations of leptin with anthropometric variables, especially visceral fat, tended to be different between the 3 apoE groups, but this was not independent and no effect was found after controlling for the other parameters in the model. A multiple regression model containing gender, subcutaneous fat, fasting glucose, triglycerides, and high-density lipoprotein (HDL) cholesterol explained 81% of the variance in leptin levels. We conclude that apoE polymorphism has no effect on the leptin level or its associations with other anthropometric and metabolic parameters.

Hereditary motor and sensory neuropathy associated with auditory neuropathy in a Gypsy family

In a Slovene Gypsy family of 19 subjects from four generations three patients with clinical characteristics compatible with hereditary motor and sensory neuropathy - Lom (HMSNL). were found They had severe distal and milder proximal muscle atrophy and weakness with areflexia of myotatic jerks. Two had facial weakness at the time when already wheelchair bound. All sensory modalities were affected distally in the limbs. Sluggish pupillary responses to light and convergence were found. They had skeletal abnormalities. One patient had polydactily on the hand. Nerve conduction studies were compatible with demyelinative polyneuropathy. Nerve biopsy showed mainly axonal loss without hypertrophic changes. Auditory neuropathy was diagnosed in all of them. None of the patients had duplication of 17p1.2-12 or point mutations in the Protein zero. Peripheral myelin protein and Connexin32 genes. Similar disorder that mapped to 8q24 was previously described in some Bulgarian and Italian Gypsy families. Members of our family may suffer from the same hereditary disease and may carry the same ancestor mutation, which was in the past spread in European Gypsy populations.

Epinephrine, potassium and the electrocardiogram during regional anaesthesia

Epinephrine lowers the serum potassium level through an effect on the beta2-receptor. It is therefore difficult to evaluate whether depression of the ST level and the T wave on the electrocardiogram, during regional anaesthesia, is caused by a high plasma epinephrine level, a low serum potassium level, or both. For this purpose, we studied the relation between electrocardiogram and the plasma epinephrine and serum potassium concentrations during 20 intra-abdominal operations performed under combined epidural and general anaesthesia and in 18 subjects receiving intercostal nerve blockade. The results show that the hypokalaemic effect of epinephrine was reduced when the plasma epinephrine concentration exceeded 3 nmol L-1. A multiple regression analysis demonstrated that the ST level and the T-wave amplitude were most consistently affected by a low serum potassium level, while a high plasma epinephrine level correlated only to a depression in the T-wave amplitude. During surgery, only serum potassium correlated with these ECG variables.

Screening for mutations in the peripheral myelin genes PMP22, MPZ and Cx32 (GJB1) in Russian Charcot-Marie-Tooth neuropathy patients

Charcot-Marie-Tooth disease (CMT) and related inherited peripheral neuropathies, including Dejerine-Sottas syndrome, congenital hypomyelination, and hereditary neuropathy with liability to pressure palsies (HNPP), are caused by mutations in three myelin genes: PMP22, MPZ and Cx32 (GJB1). The most common mutations are the 1.5 Mb CMT1A tandem duplication on chromosome 17p11.2-p12 in CMT1 patients and the reciprocal 1.5 Mb deletion in HNPP patients. We performed a mutation screening in 174 unrelated CMT patients and three HNPP families of Russian origin. The unrelated CMT patients included 108 clinically and electrophysiologically diagnosed CMT1 cases, 32 CMT2 cases, and 34 cases with unspecified CMT. Fifty-nine CMT1A duplications were found, of which 58 belonged to the CMT1 patient group. We found twelve distinct mutations in Cx32, six mutations in MPZ, and two mutations in PMP22. Of these respectively, eight, five, and two lead to a CMT1 phenotype. Eight mutations (Cx32: Ile20Asn/Gly21Ser, Met34Lys, Leu90Val, and Phe193Leu; MPZ: Asp134Gly, Lys138Asn, and Thr139Asn; PMP22: ValSer25-26del) were not reported previously. Phenotype-genotype correlations were based on nerve conduction velocity studies and mutation type.

Genomic organisation of the spinocerebellar ataxia type 7 (SCA7) gene responsible for autosomal dominant cerebellar ataxia with retinal degeneration

Autosomal dominant cerebellar ataxia with retinal degeneration (ADCA type II) is a progressive neurodegenerative disorder caused by a CAG expansion in the spinocerebellar ataxia 7 (SCA7) gene. Here, we describe the genomic organisation of the human SCA7 gene. The exon-intron boundaries were identified by sequencing plasmid subclones of a P1 artificial chromosome (PAC) clone containing the entire SCA7 gene. We found 13 exons, ranging in size from 69 to 979 bp, with all exon-intron boundaries following the GT-AG rule. The ATG initiation codon at position 554 of the cDNA occurs in exon 3 at position 12 and the coding region extends to the first five codons of exon 13, with the CAG repeat being located in exon 3 starting at codon 30. The intron sizes were determined by long-distance polymerase chain reaction with primers from neighbouring exons and by restriction mapping of the SCA7 PAC clone. The introns varied in size from 233 bp to about 40 kb, resulting in an overall size estimate for the SCA7 gene of 140 kb. Sequence analysis of intron 7 (491 bp) revealed a polymorphic GT/AC repeat, a useful intragenic marker for SCA7 in segregation studies.

A novel type of hereditary motor and sensory neuropathy characterized by a mild phenotype

BACKGROUND

Three loci for autosomal dominant hereditary motor and sensory neuropathy type I (HMSN I) or Charcot-Marie-Tooth disease type 1 (CMT1) have been identified on chromosomes 17p11.2 (CMT1A), 1q21-q23 (CMT1B), and 10q21.1-q22.1 (designated here as CMT1D). The genes involved are peripheral myelin protein 22 (PMP22), myelin protein zero (MPZ), and the early growth response element 2 (EGR2), respectively. Probably a fourth locus (CMT1C) exists since some autosomal dominant HMSN I families have been excluded for linkage with the CMT1A and CMT1B loci. Four loci for autosomal dominant hereditary motor and sensory neuropathy type II (HMSN II) or Charcot-Marie-Tooth disease type 2 (CMT2) have been localized on chromosomes 1p35-p36 (CMT2A), 3q13-q22 (CMT2B), 7p14 (CMT2D), and 3p (HMSN-P).

OBJECTIVE

To describe the clinical, electrophysiologic, and neuropathological features of a novel type of Charcot-Marie-Tooth disease.

PATIENTS AND METHODS

We performed linkage studies with anonymous DNA markers flanking the known CMT1 and CMT2 loci. Patients and their relatives underwent clinical neurologic examination and electrophysiologic testing. In the proband, a sural nerve biopsy specimen was examined.

RESULTS

Linkage studies excluded all known CMT1 and CMT2 loci. The clinical phenotype is mild and almost all affected individuals remain asymptomatic. Electrophysiologic and histopathological studies showed signs of a demyelinating neuropathy, but the phenotype is unusual for either autosomal dominant HMSN I or HMSN II.

CONCLUSION

Our findings indicate that the HMSN in this family represents a novel clinical and genetic entity.

Spinocerebellar ataxia type 7 (SCA7) - correlations between phenotype and genotype in one large Belgian family

Spinocerebellar ataxia type 7 (SCA7), in which the degenerative process also affect the retina, belongs to the category of the autosomal dominant cerebellar ataxia type II (ADCA II). We have described the neuropathology of this condition [Martin JJ, Van Regemorter N, Krols L, Brucher JM, de Barsy T, Szliwowski H, et al. On an autosomal dominant form of retino-cerebellar degeneration: an autopsy study of five patients in one family. Acta Neuropathol (Berl) 1994;88:277-286] in a very large Belgian family (CA-1). We have observed anticipation in the age of onset with increasing severity of the symptoms in consecutive generations. The SCA7 gene was mapped to chromosome 3p12-13 [David G, Abbas N, Stevanin G, Dürr A, Yvert G, Cancel G, et al. Cloning of the SCA7 gene reveals a highly unstable CAG repeat expansion. Nat Genet 1997;17:65-70; Del-Favero J, Krols L, Michalik A, Theuns J, Löfgren A, Goossens D, et al. Molecular genetic analysis of autosomal dominant cerebellar ataxia with retinal degeneration (ADCA type II) caused by CAG triplet repeat expansion. Hum Mol Genet 1998;7:177-186], and the gene identified. SCA7 is a new gene of unknown function that contains an expansion of CAG repeats in SCA7 patients. During the procedure of positional cloning, we examined 26 patients belonging to the CA-1 family and realized, in some of them, an ophthalmologic examination and neuro-imaging of the brain. This allowed us to differentiate four groups: (1) asymptomatic young carriers with 38 to 43 CAG repeats; (2) mildly symptomatic, older patients with 38-41 CAG repeats; (3) patients with the full-blown picture of SCA7 and age of onset during adolescence, with 54-55 CAG repeats; (4) children with early onset and rapid fatal course of the disease who had over 55 CAG repeats. We were able to draw correlations between clinical phenotype, age at onset and CAG repeat number and to make predictions, to some extent, as to the clinical course of the disease in new patients.

Molecular diagnostic testing in Charcot-Marie-Tooth disease and related disorders. Approaches and results

The inherited neuropathies of the peripheral nervous system are clinically and genetically a heterogeneous group of disorders. Molecular genetic studies have made major breakthroughs in unraveling the underlying gene defects, and DNA diagnosis can now be offered to a large number of families with distinct forms of hereditary peripheral neuropathies. With the currently available technology, however, molecular genetic diagnosis still remains a labor-intensive and costly procedure. We have developed an algorithm for mutation screening based on clinical phenotype, electrophysiological findings, and the relative frequencies of mutations in the distinct peripheral myelin genes.