Clinical and genetic characterization of adult‐onset leukoencephalopathy with axonal spheroids and pigmented glia associated with CSF1R mutation

Background and purpose: The clinical characteristics of colony stimulating factor 1 receptor (CSF1R) related adult‐onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) have been only partially elucidated. Methods: Clinical data from CSF1R mutation carriers who had been seen at our institutions or reported elsewhere were collected and analysed using a specific investigation sheet to standardize the data. Results: In all, 122 cases from 90 families with CSF1R mutations were identified. The mean age of onset was 43 years (range 18–78 years), the mean age at death was 53 years (range 23–84 years) and the mean disease duration was 6.8 years (range 1–29 years). Women had a significantly younger age of onset than men (40 vs. 47 years, P = 0.0006, 95% confidence interval 3.158–11.177). There was an age‐dependent penetrance that was significantly different between the sexes (P = 0.0013). Motor dysfunctions were the most frequent initial symptom in women whose diseases began in their 20s. Thinning of the corpus callosum, abnormal signalling in pyramidal tracts, diffusion‐restricted lesions and calcifications in the white matter were characteristic imaging findings of ALSP. The calcifications were more frequently reported in our case series than in the literature (54% vs. 3%). Seventy‐nine per cent of the mutations were located in the distal part of the tyrosine kinase domain of CSF1R (102 cases). There were no apparent phenotype−genotype correlations. Conclusions: The characteristics of ALSP were clarified. The phenotype of ALSP caused by CSF1R mutations is affected by sex

ALS5/SPG11/KIAA1840 mutations cause autosomal recessive axonal Charcot-Marie-Tooth disease

Charcot-Marie-Tooth disease is a group of hereditary peripheral neuropathies that share clinical characteristics of progressive distal muscle weakness and atrophy, foot deformities, distal sensory loss, as well as diminished tendon reflexes. Hundreds of causative DNA changes have been found, but much of the genetic basis of the disease is still unexplained. Mutations in the ALS5/SPG11/KIAA1840 gene are a frequent cause of autosomal recessive hereditary spastic paraplegia with thin corpus callosum and peripheral axonal neuropathy, and account for similar to 40% of autosomal recessive juvenile amyotrophic lateral sclerosis. The overlap of axonal Charcot-Marie-Tooth disease with both diseases, as well as the common autosomal recessive inheritance pattern of thin corpus callosum and axonal Charcot-Marie-Tooth disease in three related patients, prompted us to analyse the ALS5/SPG11/KIAA1840 gene in affected individuals with autosomal recessive axonal Charcot-Marie-Tooth disease. We investigated 28 unrelated families with autosomal recessive axonal Charcot-Marie-Tooth disease defined by clinical, electrophysiological, as well as pathological evaluation. Besides, we screened for all the known genes related to axonal autosomal recessive Charcot-Marie-Tooth disease (CMT2A2/HMSN2A2/MFN2, CMT2B1/LMNA, CMT2B2/MED25, CMT2B5/NEFL, ARCMT2F/dHMN2B/HSPB1, CMT2K/GDAP1, CMT2P/LRSAM1, CMT2R/TRIM2, CMT2S/IGHMBP2, CMT2T/HSJ1, CMTRID/COX6A1, ARAN-NM/HINT and GAN/GAN), for the genes related to autosomal recessive hereditary spastic paraplegia with thin corpus callosum and axonal peripheral neuropathy (SPG7/PGN, SPG15/ZFYVE26, SPG21/ACP33, SPG35/FA2H, SPG46/GBA2, SPG55/C12orf65 and SPG56/CYP2U1), as well as for the causative gene of peripheral neuropathy with or without agenesis of the corpus callosum (SLC12A6). Mitochondrial disorders related to Charcot-Marie-Tooth disease type 2 were also excluded by sequencing POLG and TYMP genes. An additional locus for autosomal recessive Charcot-Marie-Tooth disease type 2H on chromosome 8q13-21.1 was excluded by linkage analysis. Pedigrees originated in Italy, Brazil, Canada, England, Iran, and Japan. Interestingly, we identified 15 ALS5/SPG11/KIAA1840 mutations in 12 families (two sequence variants were never reported before, p.Gln198* and p.Pro2212fs*5). No large deletions/duplications were detected in these patients. The novel mutations seemed to be pathogenic since they co-segregated with the disease in all pedigrees and were absent in 300 unrelated controls. Furthermore, in silico analysis predicted their pathogenic effect. Our results indicate that ALS5/SPG11/KIAA1840 is the causative gene of a wide spectrum of clinical features, including autosomal recessive axonal Charcot-Marie-Tooth disease

MKLN1 splicing defect in dogs with lethal acrodermatitis

Lethal acrodermatitis (LAD) is a genodermatosis with monogenic autosomal recessive inheritance in Bull Terriers and Miniature Bull Terriers. The LAD phenotype is characterized by poor growth, immune deficiency, and skin lesions, especially at the paws. Utilizing a combination of genome wide association study and haplotype analysis, we mapped the LAD locus to a critical interval of similar to 1.11 Mb on chromosome 14. Whole genome sequencing of an LAD affected dog revealed a splice region variant in the MKLN1 gene that was not present in 191 control genomes (chr14:5,731,405T>G or MKLN/:c.400+3A>C). This variant showed perfect association in a larger combined Bull Terrier/Miniature Bull Terrier cohort of 46 cases and 294 controls. The variant was absent from 462 genetically diverse control dogs of 62 other dog breeds. RT-PCR analysis of skin RNA from an affected and a control dog demonstrated skipping of exon 4 in the MKLN1 transcripts of the LAD affected dog, which leads to a shift in the MKLN1 reading frame. MKLN1 encodes the widely expressed intracellular protein muskelin 1, for which diverse functions in cell adhesion, morphology, spreading, and intracellular transport processes are discussed. While the pathogenesis of LAD remains unclear, our data facilitate genetic testing of Bull Terriers and Miniature Bull Terriers to prevent the unintentional production of LAD affected dogs. This study may provide a starting point to further clarify the elusive physiological role of muskelin 1 in vivo.Peer reviewe

ENERGY-BASED DAMPING ESTIMATION OF STEEL BRIDGES AND ITS APPLICABILITY TO DAMAGE DETECTION

The Thirteenth East Asia-Pacific Conference on Structural Engineering and Construction (EASEC-13), September 11-13, 2013, Sapporo, Japan