Hereditary epidermolytic palmoplantar keratosis due to a novel desmoglein-1 mutation: A case report.

Key Clinical Message: Keratosis palmoplantaris striata type I (SPPK-I) is a rare autosomal-dominant type of hereditary epidermolytic palmoplantar keratoderma, which can be caused by mutations in desmoglein-1 (DSG-1). Patients suffer from hyperkeratotic plaques and painful palmoplantar fissures. Unfortunately, treatment options including salicylic vaseline, topical corticosteroids, phototherapy, and retinoids are inefficient. Abstract: Hereditary palmoplantar keratodermas (PPKs) represent a heterogeneous group of rare skin disorders with epidermal palmoplantar hyperkeratosis. Mutations in the desmoglein 1 gene (DSG1), a transmembrane glycoprotein, have been reported primarily in striate PPKs. We report a patient with keratosis palmoplantaris striata type I (SPPK-I) with a specific pathogenic variant [c.349C>T, p.(Arg117*)] in DSG1. Despite increased understanding, effective treatment options for PPK, including SPPK-I, remain limited.

Cutaneous Vascular Malformations in a 53-Year-Old Woman With Neurologic Symptoms.

A woman in her 50s presented with bluish, keratotic papules and nodules on the lower legs and lipolymphedema of the lower legs. What is your diagnosis?

Recurrent necrotizing cellulitis, multi-organ autoimmune disease and humoral immunodeficiency due to a novel NFKB1 frameshift mutation.

BACKGROUND: Mutations in NFKB1(nuclear factor of kappa light polypeptide gene enhancer in B-cells 1) are associated with a variety of clinical symptoms, including lymphadenopathy, splenomegaly, hepatomegaly, autoimmune haemolytic anaemia, arthralgia, recurrent respiratory tract infections and post-operative necrotizing cellulitis. CASE PRESENTATION: We describe a case of a 47-year-old man, who presented with deep necrotizing cellulitis after incision of a submucous abscess by a dentist. Surgical intervention led to a massive progress. Pyoderma gangraenosum (PG) was diagnosed clinically and confirmed histopathologically. High dose corticosteroids and intravenous immunoglobulins (IVIG) improved wound healing dramatically. Until now, immune mediated inflammation events not only affected the skin, but also multiple inner organs, i.e. the heart, lungs and gut. Sequencing of all coding exons of NFKB1 revealed a heterozygous 1bp deletion in exon 23 predicting a frameshift starting at codon Ala891 and resulting in a subsequent stop codon at position 6 in the new reading frame: NM_003998.4: c.2671del; p.(Ala891Glnfs*6) Acute episodes were always successfully treated with corticosteroids, IVIG and concomitant antibiotics. To prevent further exacerbations, the patient receives IVIG once a month, low-dose corticosteroids and methotrexate. CONCLUSION: This is the first case of a patient with recurrent necrotizing cellulitis and immune mediated multi-organ involvement (heart, lungs, intestine) carrying the novel frameshift mutation c.2671del (p.Ala891Glnfs*6) in NFKB1 effectively treated with IVIG, low-dose corticosteroids and methotrexate.

Carrier testing for autosomal recessive disorders: a look at current practice in Germany.

Counseling recurrence risks for monogenic disorders is one of the mainstays of human genetics. However, in practice, consultations concerning autosomal recessive disorders exceed the simple conveyance of a 25 % recurrence risk for future offspring. Medical geneticists should be aware of the multifaceted way in which autosomal recessive disorders can pose a diagnostic and counseling challenge in their daily lives and of the pitfalls they might encounter. Although the intentional or incidental detection of carrier states for autosomal recessive diseases happens more and more frequently, our current practice when clarifying their associated reproductive risks remains unsystematic and often subjectively guided. We question whether the approach of focusing on small recurrence risks for a single familial disease with extensive single-gene tests in the partner of a known carrier truly addresses the counseling needs of a couple seeking preconceptional genetic advice. Different perspectives between patients and medical practitioners (or between different medical practitioners) on "acceptable risks" or the extent to which such risks must be minimized raise the question of whether existing professional guidelines need to be clarified.

Adipose Tissue in Multiple Symmetric Lipomatosis Shows Features of Brown/Beige Fat.

INTRODUCTION: Multiple symmetric lipomatosis (MSL) (syn.: Launois-Bensaude Syndrome, benign symmetric lipomatosis) is a rare disease of fatty tissue. The pathophysiology of MSL still remains unclear, although several approaches have been described in order to understand it. Beside morphological characteristics and some molecular cell biological approaches, little is known about the histological and immunohistochemical characterization of adipose tissue from patients with MSL. METHODS: From the 45 patients with MSL in our database, 10 were included in the study. Fat tissue samples were collected from affected and unaffected areas. The forearm served as a control area as this area is not affected in MSL. The specimens were analyzed after selected stainings were taken (hematoxylin-eosin = HE, Elastica van Gieson, Ladewig, CD200, CIDEA, myf5, p107, Prdm16, Sca-1, syndecan, UCP1, MAC387, Glut4). RESULTS: In patients suffering from MSL, no macroscopic or microscopic morphological difference could be found between affected and unaffected adipose tissue in HE stainings. The majority of samples showed positivity for UCP1 (9/10 clinically affected tissues, 7/10 clinically unaffected tissues) and CD200. CONCLUSION: Marker profiles support the hypothesis that affected adipose tissue derives from brown or beige adipose tissue rather than from white fat. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Calcyphosine-like (CAPSL) is regulated in Multiple Symmetric Lipomatosis and is involved in Adipogenesis.

Little is known on the causes and pathogenesis of the adipose tissue disorder (familial) Multiple Symmetric Lipomatosis (MSL). In a four-generation MSL-family, we performed whole exome sequencing (WES) in 3 affected individuals and 1 obligate carrier and identified Calcyphosine-like (CAPSL) as the most promising candidate gene for this family. Screening of 21 independent patients excluded CAPSL coding sequence variants as a common monogenic cause, but using immunohistochemistry we found that CAPSL was down-regulated in adipose tissue not only from the index patient but also in 10 independent sporadic MSL-patients. This suggests that CAPSL is regulated in sporadic MSL irrespective of the underlying genetic/multifactorial cause. Furthermore, we cultivated pre-adipocytes from MSL-patients and generated 3T3-L1-based Capsl knockout and overexpressing cell models showing altered autophagy, adipogenesis, lipogenesis and Sirtuin-1 (SIRT1) expression. CAPSL seems to be involved in adipocyte biology and perturbation of autophagy is a potential mechanism in the pathogenesis of MSL. Downregulation of CAPSL and upregulation of UCP1 were common features in MSL fat while the known MSL genes MFN2 and LIPE did not show consistent alterations. CAPSL immunostainings could serve as first diagnostic tools in MSL clinical care with a potential to improve time to diagnosis and healthcare options.

Multiple Symmetric Lipomatosis: New Classification System Based on the Largest German Patient Cohort.

BACKGROUND: Multiple symmetric lipomatosis (MSL) is defined as a disorder of nonencapsulated adipose tissue growth. Its prevalence is indicated as 1:25,000 and affects, as stated in the literature, mainly Mediterranean males (male:female ratio of 15:1). Phenotypes are still classified as defined by Donhauser in 1991. We report clinical and phenotypic data of the largest patient cohort investigated in Germany so far. METHODS: Forty-five patients diagnosed with MSL at the University Hospital Regensburg between 2007 and 2017 were photographed, clinically examined, and blood samples were taken. Based on the photographs (n = 33), 11 independent observers assessed patients using the Donhauser classification. Furthermore, the bodies of all patients were subdivided into 12 body areas, and the viewers had to indicate all MSL-affected areas per patient. Prevalence was calculated, comorbidities were assessed, and blood samples were analyzed. RESULTS: According to the established Donhauser classification, less than 50% of the patients could be classified. Therefore, based on the constellations of MSL-affected body areas, a new classification that divides phenotypes of MSL into 5 types (Ia, Ib, Ic, II, and III) was set up and was able to cover 100% of our patients. The male to female ratio was found to be 1:2.5 (male:female). Prevalence of MSL in the catchment area was found to be 1:25,000. Hypercholesterinemia and hypothyroidism were frequent comorbidities, and blood analyses were normal besides a hypercholesterinemia. DISCUSSION: The new proposed classification system describes 5 subtypes and allowed to classify all assessed patients. Male to female ratio (1:2.5) contradicted most previous publications.

Role of Anti-PCSK9 Antibodies in the Treatment of Patients with Statin Intolerance.

Statin intolerance is usually defined as the inability of a patient to tolerate statintreatment due to muscle-related complaints. While randomised trials show that these complaints occure with similar frequency in patients receiving placebo, namely in up to ~5% of the subjects, and data from registries as well as clinical experience indicate a much higher frequency of up to ~30%. The lack of standard definition or of a diagnostic marker of statin intolerance confounds the problem. The diagnosis remains subjective based on the symptoms the patient reports. Therefore, a large number of patients who need a statin are not receiving it, or receiving only very-low and/or intermittent doses unable to achieve a robust decrease in low-density lipoprotein cholesterol (LDL-C), leaving patients at high or very high risk for cardiovascular events requiring an alternative form of lipid-lowering therapy. Until recently, the only available alternatives were niacin, ezetimibe, bile-acid sequestrants and fibrates that decrease LDL-C concentrations by up to 15-20%. Recently the fully human monoclonal antibodies against proprotein convertase subtilisin/kexin 9 (PCSK9), alirocumab (Praluent®) and evolocumab (Repatha®), which have been shown to decrease LDL-C by up to 70% have been approved in Europe for use in patients with primary hypercholesterolemia not at LDL-C target while on maximally tolerated lipid-lowering therapy and specifically for patients with statin intolerance and in the USA for patients with atherosclerotic cardiovascular disease or familial hypercholesterolemia requiring additional LDL-C lowering. Ongoing large clinical trials with cardiovascular endpoints will provide a definitive answer for the role of anti-PCSK9 antibodies in clinical practice.

Apolipoprotein(a) Antisense Oligonucleotides: A New Treatment Option for Lowering Elevated Lipoprotein(a)?

BACKGROUND: Lipoprotein(a) [Lp(a)] is a particle similar to LDL that contains an additional protein called apolipoprotein(a) [apo(a)]. Recent epidemiologic and Mendelian randomization studies have provided evidence that Lp(a) may be causally related to the pathogenesis of atherosclerosis and cardiovascular disease (CVD). While the risk association between Lp(a) concentrations and CVD is weak it seems to be continuous in shape and without an obvious threshold for Lp(a) levels. METHODS: Circulating concentrations of Lp(a) are genetically determined and desirable levels are < 50 mg/dl. A plasma concentration of 60 mg/dl is associated with an odds ratio for coronary heart disease of about 1.5 after adjustment for other cardiovascular risk factors. RESULTS: Extended-release niacin is the pharmacologic means of choice for decreasing elevated Lp(a) levels by ~20-30% but it is often poorly tolerated due to adverse reactions. Diet, exercise and lipid-lowering drugs such as statins, fibrates and ezetimibe are without effect. In patients with severe progressive CVD and very high Lp(a) levels, lipoprotein apheresis may be used to decrease Lp(a) concentrations. However, it is an expensive and impractical treatment for most patients and its feasibility depends on the healthcare reimbursement system of the respective country. Since no established treatment reduces Lp(a) without influencing other lipoproteins, there has been no trial examining whether decreasing Lp(a) concentrations translates to clinical benefits. CONCLUSION: Recently, an antisense oligonucleotide against apo(a), IONIS-APO(a)Rx, has been shown to selectively decrease Lp(a) by ~80%. A phase 2 study with this drug has been completed in late 2015 and results are expected to be published soon.

Proton-sensing G protein-coupled receptors as regulators of cell proliferation and migration during tumor growth and wound healing.

Dysregulation of pH is a feature of both tumor growth and tissue repair. In tumors, microenvironmental changes, like in lactate metabolism, lead to altered intra- and extracellular pH (pHi , pHe ) and vice versa. In wounds, barrier disruption results in extensive variations in pHe on the wound surface. It is known that altered extracellular proton concentrations have a major impact on cell turnover and migration as well as on the metabolic activity of cells involved in tumor spread and wound closure. The proton-sensing G protein-coupled receptors (GPCRs) GPR4, GPR65 (TDAG8), GPR68 (OGR1) and GPR132 (G2A) are activated via a decrease in pHe and transduce this signal to molecular intracellular pathways. Based on the current knowledge, we speculate on the role of proton-sensing GPCRs in wound healing and on their potential as mechanistic linkers of tumor growth and tissue repair.

NHE1 expression at wound margins increases time-dependently during physiological healing.

Wound repair is an orchestrated process, encompassing the phases of inflammation, proliferation and tissue remodeling. In this context, sodium hydrogen exchanger 1 (NHE1) is crucial to epidermal barrier integrity and acidification. Recently, we found that extracellular pH (pHe) on wound surfaces is dramatically increased initially after barrier disruption, and that pHe decreases gradually during physiological healing. Additionally, we have shown that spatial NHE1-patterns account for pHe-gradients on surfaces of chronic wounds. Here, we show that NHE1-expression is very low at margins initially after wounding and that it increases massively during the time-course of physiolgical healing. This finding is in accordance with the decrease of pHe on wound surfaces, which we reported on in previous works. Thus, we show that NHE1 is an interesting target when it comes to modification of surface pHe on wounds, both acute and chronic, and that NHE1 is time-dependently regulated in physiological healing.

Transcription Profile in Sporadic Multiple Symmetric Lipomatosis Reveals Differential Expression at the Level of Adipose Tissue-Derived Stem Cells.

BACKGROUND: The cause of the rare fat distribution disorder multiple symmetric lipomatosis is unknown. Independent reports suggest a higher proliferative activity, hormone resistance, and involvement of mitochondrial function in the disease. METHODS: The authors performed morphologic comparison of affected and unaffected tissues in five unrelated patients and generated adipose-derived stem cell cultures from the tissue samples and characterized them as a possible cellular model of multiple symmetric lipomatosis evolution. The authors investigated proliferative activity and the expression of genes relevant to disease processes. RESULTS: There was no difference in the morphologic appearance and the surface marker profile. Stem cells from lipomatous tissue showed significantly higher proliferative activity. Polymerase chain reaction arrays showed marked changes in genes associated with proliferation, hormonal regulation, and mitochondria. The authors show that multiple symmetric lipomatosis tissue is morphologically and histologically different from regular subcutaneous fat. CONCLUSIONS: This study indicates an involvement of mesenchymal stem cells in the pathogenesis of multiple symmetric lipomatosis and that the evolution of multiple symmetric lipomatosis tissue is a process driven by an inherent defect of the respective cell clone(s). Further molecular genetics and functional analysis will be required to unravel the pathogenetic mechanism underlying the derailment in fat cell metabolism and proliferation. Here, the authors show for the first time that adipose-derived stem cells exhibit many characteristics previously described for native multiple symmetric lipomatosis fat tissue and propose that they are therefore an excellent tool for further functional investigations in multiple symmetric lipomatosis and other disorders of the fat tissue. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, V.

Erythrodermia Congenitalis Ichthyosiformis Bullosa of Brocq.

A 50-year-old man presented with congenital scaling and hyperkeratosis on his palms, the soles of his feet and the extensor areas of his joints. The flexural areas were unaffected. His maternal grandmother, questionably his maternal uncle, his mother, all three brothers, one of his two sisters as well as two nephews and three nieces have or had similar skin changes. A punch biopsy was taken from the left palm. Clinical and histological signs led to the diagnosis of erythrodermia congenitalis ichthyosiformis bullosa of Brocq. We confirmed this genetically and found a heterozygous duplication (c.1752dupT) in the keratin 1 gene (KRT-1). To our knowledge, this is the first case of this skin condition reported in the literature with a heterozygous duplication (c.1752dupT) in KRT-1.

Modulation of human endogenous retrovirus (HERV) transcription during persistent and de novo HIV-1 infection.

BACKGROUND: The human genome contains multiple LTR elements including human endogenous retroviruses (HERVs) that together account for approximately 8-9% of the genomic DNA. At least 40 different HERV groups have been assigned to three major HERV classes on the basis of their homologies to exogenous retroviruses. Although most HERVs are silenced by a variety of genetic and epigenetic mechanisms, they may be reactivated by environmental stimuli such as exogenous viruses and thus may contribute to pathogenic conditions. The objective of this study was to perform an in-depth analysis of the influence of HIV-1 infection on HERV activity in different cell types. RESULTS: A retrovirus-specific microarray that covers major HERV groups from all three classes was used to analyze HERV transcription patterns in three persistently HIV-1 infected cell lines of different cellular origins and in their uninfected counterparts. All three persistently infected cell lines showed increased transcription of multiple class I and II HERV groups. Up-regulated transcription of five HERV taxa (HERV-E, HERV-T, HERV-K (HML-10) and two ERV9 subgroups) was confirmed by quantitative reverse transcriptase PCR analysis and could be reversed by knock-down of HIV-1 expression with HIV-1-specific siRNAs. Cells infected de novo by HIV-1 showed stronger transcriptional up-regulation of the HERV-K (HML-2) group than persistently infected cells of the same origin. Analysis of transcripts from individual members of this group revealed up-regulation of predominantly two proviral loci (ERVK-7 and ERVK-15) on chromosomes 1q22 and 7q34 in persistently infected KE37.1 cells, as well as in de novo HIV-1 infected LC5 cells, while only one single HML-2 locus (ERV-K6) on chromosome 7p22.1 was activated in persistently infected LC5 cells. CONCLUSIONS: Our results demonstrate that HIV-1 can alter HERV transcription patterns of infected cells and indicate a correlation between activation of HERV elements and the level of HIV-1 production. Moreover, our results suggest that the effects of HIV-1 on HERV activity may be far more extensive and complex than anticipated from initial studies with clinical material.

The missing "link": an autosomal recessive short stature syndrome caused by a hypofunctional XYLT1 mutation.

Proteoglycan (PG) synthesis begins with the sequential addition of a "linker chain", made up of four sugar residues, to a specific region of a core protein. Defects in the enzymes catalyzing steps two to four of the linker chain synthesis have been shown to cause autosomal recessive human phenotypes while no mutation has yet been reported in humans for the xylosyltransferases 1 and 2 (XT1 and XT2), the initiating enzymes in the linker chain formation. Here, we present a consanguineous Turkish family with two affected individuals presenting with short stature, distinct facial features, alterations of fat distribution, and moderate intellectual disability. X-rays showed only mild skeletal changes in the form of a short femoral neck, stocky and plump long bones and thickened ribs. Using a combination of whole-exome sequencing (WES), determination of homozygous stretches by WES variants, and classical linkage analysis, we identified the homozygous missense mutation c.C1441T in XYLT1, encoding XT1, within a large homozygous stretch on chromosome 16p13.12-p12.1. The mutation co-segregated with the phenotype in the family, is not found in over 13,000 alleles in the exome variant server and is predicted to change a highly conserved arginine at position 481 (p.R481W) located in the putative catalytical domain. Immunostaining of primary patient fibroblasts showed a loss of predominance of Golgi localization in mutant cells. Moreover, western blot analysis of decorin in cell culture supernatant demonstrated glycosylation differences between patient and control cells. Our data provide evidence that functional alterations of XT1 cause an autosomal recessive short stature syndrome associated with intellectual disability.

Increasing the yield in targeted next-generation sequencing by implicating CNV analysis, non-coding exons and the overall variant load: the example of retinal dystrophies.

Retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA) are major causes of blindness. They result from mutations in many genes which has long hampered comprehensive genetic analysis. Recently, targeted next-generation sequencing (NGS) has proven useful to overcome this limitation. To uncover "hidden mutations" such as copy number variations (CNVs) and mutations in non-coding regions, we extended the use of NGS data by quantitative readout for the exons of 55 RP and LCA genes in 126 patients, and by including non-coding 5' exons. We detected several causative CNVs which were key to the diagnosis in hitherto unsolved constellations, e.g. hemizygous point mutations in consanguineous families, and CNVs complemented apparently monoallelic recessive alleles. Mutations of non-coding exon 1 of EYS revealed its contribution to disease. In view of the high carrier frequency for retinal disease gene mutations in the general population, we considered the overall variant load in each patient to assess if a mutation was causative or reflected accidental carriership in patients with mutations in several genes or with single recessive alleles. For example, truncating mutations in RP1, a gene implicated in both recessive and dominant RP, were causative in biallelic constellations, unrelated to disease when heterozygous on a biallelic mutation background of another gene, or even non-pathogenic if close to the C-terminus. Patients with mutations in several loci were common, but without evidence for di- or oligogenic inheritance. Although the number of targeted genes was low compared to previous studies, the mutation detection rate was highest (70%) which likely results from completeness and depth of coverage, and quantitative data analysis. CNV analysis should routinely be applied in targeted NGS, and mutations in non-coding exons give reason to systematically include 5'-UTRs in disease gene or exome panels. Consideration of all variants is indispensable because even truncating mutations may be misleading.

Recessive TRAPPC11 mutations cause a disease spectrum of limb girdle muscular dystrophy and myopathy with movement disorder and intellectual disability.

Myopathies are a clinically and etiologically heterogeneous group of disorders that can range from limb girdle muscular dystrophy (LGMD) to syndromic forms with associated features including intellectual disability. Here, we report the identification of mutations in transport protein particle complex 11 (TRAPPC11) in three individuals of a consanguineous Syrian family presenting with LGMD and in five individuals of Hutterite descent presenting with myopathy, infantile hyperkinetic movements, ataxia, and intellectual disability. By using a combination of whole-exome or genome sequencing with homozygosity mapping, we identified the homozygous c.2938G>A (p.Gly980Arg) missense mutation within the gryzun domain of TRAPPC11 in the Syrian LGMD family and the homozygous c.1287+5G>A splice-site mutation resulting in a 58 amino acid in-frame deletion (p.Ala372_Ser429del) in the foie gras domain of TRAPPC11 in the Hutterite families. TRAPPC11 encodes a component of the multiprotein TRAPP complex involved in membrane trafficking. We demonstrate that both mutations impair the binding ability of TRAPPC11 to other TRAPP complex components and disrupt the Golgi apparatus architecture. Marker trafficking experiments for the p.Ala372_Ser429del deletion indicated normal ER-to-Golgi trafficking but dramatically delayed exit from the Golgi to the cell surface. Moreover, we observed alterations of the lysosomal membrane glycoproteins lysosome-associated membrane protein 1 (LAMP1) and LAMP2 as a consequence of TRAPPC11 dysfunction supporting a defect in the transport of secretory proteins as the underlying pathomechanism.

Increasing SMN levels using the histone deacetylase inhibitor SAHA ameliorates defects in skeletal muscle microvasculature in a mouse model of severe spinal muscular atrophy.

Spinal muscular atrophy (SMA), a primarily childhood form of motor neuron disease, is caused by reduced levels of a single, ubiquitously expressed protein: the survival motor neuron (SMN) protein. Low levels of SMN cause motor neuron degeneration but recent reports describe effects of low SMN levels in multiple tissues and organs, including the vasculature. Previously we have reported a significant defect in the vascular beds of SMA affected skeletal muscle. Here we examine the effects of ubiquitously increasing SMN levels, via treatment with the histone deacetylase inhibitor SAHA, on this vascular defect in the Taiwanese mouse: FVB.Cg-Tg(SMN2)2Hung Smn1(tm1Hung)/J mouse model of severe SMA. SAHA treatment resulted in an increase in the weight of SMA mice compared to untreated SMA mice and almost completely restored motor function at P10, the late symptomatic time point analysed. Vascular density in skeletal muscle was then assessed by morphological quantitation of immunofluorescence staining of vessels and quantitative fluorescent western blotting for a key endothelial protein PECAM-1. At P10 a severe vascular defect was present with a significant (P<0.01) ~82% reduction in vascular density in SMA mice when compared to control littermates. SAHA significantly increases SMN levels and also increased vascular density in SMA mice (P<0.05), suggesting that the vascular defect in SMA mice is amenable to SAHA treatment.

Plastin 3 ameliorates spinal muscular atrophy via delayed axon pruning and improves neuromuscular junction functionality.

F-actin bundling plastin 3 (PLS3) is a fully protective modifier of the neuromuscular disease spinal muscular atrophy (SMA), the most common genetic cause of infant death. The generation of a conditional PLS3-over-expressing mouse and its breeding into an SMA background allowed us to decipher the exact biological mechanism underlying PLS3-mediated SMA protection. We show that PLS3 is a key regulator that restores main processes depending on actin dynamics in SMA motor neurons (MNs). MN soma size significantly increased and a higher number of afferent proprioceptive inputs were counted in SMAPLS3 compared with SMA mice. PLS3 increased presynaptic F-actin amount, rescued synaptic vesicle and active zones content, restored the organization of readily releasable pool of vesicles and increased the quantal content of the neuromuscular junctions (NMJs). Most remarkably, PLS3 over-expression led to a stabilization of axons which, in turn, resulted in a significant delay of axon pruning, counteracting poor axonal connectivity at SMA NMJs. These findings together with the observation of increased endplate and muscle fiber size upon MN-specific PLS3 over-expression suggest that PLS3 significantly improves neuromuscular transmission. Indeed, ubiquitous over-expression moderately improved survival and motor function in SMA mice. As PLS3 seems to act independently of Smn, PLS3 might be a potential therapeutic target not only in SMA but also in other MN diseases.