Characteristics of Patients With Late-Onset Pompe Disease in France: Insights From the French Pompe Registry in 2022.

BACKGROUND AND OBJECTIVES: The French Pompe disease registry was created in 2004 for study of the natural course of the disease in patients. It rapidly became a major tool for assessing the long-term efficacy of enzyme replacement therapy (ERT) after the market release of alglucosidase-alfa. METHODS: Approximately 10 years after publication of the baseline characteristics of the 126 initial patients of the French Late-Onset Pompe Disease registry, we provide here an update of the clinical and biological features of patients included in this registry. RESULTS: We describe 210 patients followed at 31 hospital-based French neuromuscular or metabolic centers. The median age at inclusion was 48.67 ± 14.91 years. The first symptom was progressive lower limb muscle weakness, either isolated (50%) or associated with respiratory symptoms (18%), at a median age of 38 ± 14.9 years. At inclusion, 64% of the patients were able to walk independently and 14% needed a wheelchair. Positive associations were found between motor function measure, manual motor test, and 6-minute walk test (6MWT) results, and these parameters were inversely associated with the time taken to sit up from a lying position at inclusion. Seventy-two patients had been followed for at least 10 years in the registry. Thirty-three patients remained untreated a median of 12 years after symptom onset. The standard ERT dose was administered for 177 patients. DISCUSSION: This update confirms previous findings for the adult population included in the French Pompe disease registry, but with a lower clinical severity at inclusion, suggesting that this rare disease is now diagnosed earlier; thanks to greater awareness among physicians. The 6MWT remains an important method for assessing motor performance and walking ability. The French Pompe disease registry provides an exhaustive, nationwide overview of Pompe disease and can be used to assess individual and global responses to future treatments.

Clinical and Molecular Spectrum Associated with COL6A3 c.7447A>G p.(Lys2483Glu) Variant: Elucidating its Role in Collagen VI-related Myopathies.

BACKGROUND: Dominant and recessive autosomal pathogenic variants in the three major genes (COL6A1-A2-A3) encoding the extracellular matrix protein collagen VI underlie a group of myopathies ranging from early-onset severe conditions (Ullrich congenital muscular dystrophy) to milder forms maintaining independent ambulation (Bethlem myopathy). Diagnosis is based on the combination of clinical presentation, muscle MRI, muscle biopsy, analysis of collagen VI secretion, and COL6A1-A2-A3 genetic analysis, the interpretation of which can be challenging. OBJECTIVE: To refine the phenotypical spectrum associated with the frequent COL6A3 missense variant c.7447A>G (p.Lys2483Glu). METHODS: We report the clinical and molecular findings in 16 patients: 12 patients carrying this variant in compound heterozygosity with another COL6A3 variant, and four homozygous patients. RESULTS: Patients carrying this variant in compound heterozygosity with a truncating COL6A3 variant exhibit a phenotype consistent with COL6-related myopathies (COL6-RM), with joint contractures, proximal weakness and skin abnormalities. All remain ambulant in adulthood and only three have mild respiratory involvement. Most show typical muscle MRI findings. In five patients, reduced collagen VI secretion was observed in skin fibroblasts cultures. All tested parents were unaffected heterozygous carriers. Conversely, two out of four homozygous patients did not present with the classical COL6-RM clinical and imaging findings. Collagen VI immunolabelling on cultured fibroblasts revealed rather normal secretion in one and reduced secretion in another. Muscle biopsy from one homozygous patient showed myofibrillar disorganization and rimmed vacuoles. CONCLUSIONS: In light of our results, we postulate that the COL6A3 variant c.7447A>G may act as a modulator of the clinical phenotype. Thus, in patients with a typical COL6-RM phenotype, a second variant must be thoroughly searched for, while for patients with atypical phenotypes further investigations should be conducted to exclude alternative causes. This works expands the clinical and molecular spectrum of COLVI-related myopathies.

Confounding clinical presentation and different disease progression in CMT4B1.

We report seven Charcot-Marie-Tooth 4B1 (CMT4B1) patients from four families with distinctive features, presenting with severe distal weakness and cranial nerve involvement. Patient from family 1 presented with congenital varus foot deformity, progressive distal and proximal weakness leading to loss of ambulation at 14 years, bilateral facial palsy and prominent bulbar involvement. In three siblings from family 2, still ambulant in the second decade, neuropathy was associated with marked sweating and Arnold-Chiari syndrome. Patient from family 3, wheelchair-bound by 17 years, suffered from recurrent intestinal occlusion due to a mesenteric malformation. Patients from family 4, wheelchair-bound from age 6 years, were first diagnosed with type 1 Usher syndrome with congenital deafness and retinitis pigmentosa. CMT4B1 diagnosis was based upon suggestive clinical features and confirmed by the presence of recessive mutations in the MTMR2 gene. Our results expand the genetic and phenotypic spectrum of CMT4B1, which may include autonomic system involvement.

Efficacy and Safety of Octagam® in Patients With Chronic Inflammatory Demyelinating Polyneuropathy.

INTRODUCTION: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a debilitating autoimmune neuropathy that is treated with intravenous immunoglobulin (IVIG). The aim of this retrospective study was to investigate the efficacy and safety of the sucrose-free IVIG Octagam® (Octapharma AG, Lachen, Switzerland) in patients with CIDP. METHODS: Data from 47 patients who received at least one dose of Octagam were collected from the records of 11 centres in France. Efficacy was assessed using Overall Neuropathy Limitation Scale (ONLS). Safety was evaluated using adverse event rates. RESULTS: Data from 24 patients who were IVIG naïve (n = 11) or had stopped IVIG ≥ 12 weeks before   initiation of Octagam therapy (washout group; n = 13) were included in the efficacy analysis. At 4 months post-initiation of Octagam treatment, 41.7% of patients had improved their functional status (decrease of ≥ 1 ONLS score) with a significant change   in the ONLS score from baseline (- 0.42; p = 0.04; signed test). Functional status was reduced in only two patients: one patient in the IVIG-naïve group and one patient in the IVIG-washout group. All 47 patients were included in the safety analysis, which showed that Octagam was well tolerated, with a frequency of 0.04 adverse events per Octagam course. The most common adverse drug reaction was headache. CONCLUSIONS: These real-life results are consistent with the efficacy and safety of IVIG reported in randomised controlled studies. A long-term prospective study of Octagam in patients with CIDP is warranted. FUNDING: Octapharma, France SAS.

Skin Biopsy Findings in Patients With CMT1A: Baseline Data From the CLN-PXT3003-01 Study Provide New Insights Into the Pathophysiology of the Disorder.

Charcot-Marie-Tooth disease type 1A (CMT1A), the most common form of Charcot-Marie-Tooth diseases, is a demyelinating neuropathy caused by a deletion encompassing the gene coding for PMP22, a myelin protein of the peripheral nervous system. Although myelinated fibers are mostly involved in CMT1A, some patients experience neuropathic pain. We thus investigated whether unmyelinated fibers are lost in CMT1A. Skin biopsies were taken from the distal portion of the leg of 80 patients with CMT1A as part of the PXT30003-01 study and processed for quantification of intraepidermal nerve fiber density (IENFD). Mean IENFD was significantly lower in CMT1A patients than in healthy controls. Although the data were highly dispersed, IENFD tended to decrease with age and was higher overall in female patients and controls than male patients and controls. This study shows that small nerve fibers are affected in CMT1A and that this correlates with pin sensitivity. The density of epidermal Langerhans cells (LCs) was also significantly reduced in CMT1A patients, suggesting the involvement of LCs in neuropathic pain processes. These findings raise several questions concerning the interactions of Schwann cells and LCs with unmyelinated fibers in CMT1A. Moreover, they suggest that factors other than PMP22 gene dosage are involved in small fiber pathology in CMT1A.

Hereditary neuropathy with liability to pressure palsy in patients under 30 years old: Neurophysiological data and proposed electrodiagnostic criteria.

INTRODUCTION: In young patients with mononeuropathy who lack family history and precipitating factors, hereditary neuropathy with liability to pressure palsy (HNPP) may be a possibility. Our objective is to propose neurophysiological criteria for HNPP in patients <30 years of age. METHODS: We conducted a national multicenter retrospective clinical and neurophysiological study in patients under 30 with genetically confirmed HNPP. RESULTS: All of the 51 patients included in the study had at least 1 demyelinating pattern in 2 asymptomatic nerves, and 3 abnormalities were found in almost 90%, including slowed motor nerve conduction velocity across the elbow in at least 1 ulnar nerve (97.5%), increased distal motor latency (DML) in at least 1 fibular nerve (95.8%), and increased DML in both median nerves (89%). Age influenced DML slightly only in the fibular nerve. DISCUSSION: Dissemination of nerve involvement in HNPP incites to perform a complete nerve conduction study. including bilateral ulnar, fibular, and median nerves. Muscle Nerve 57: 217-221, 2018.

Anti-MAG antibodies in 202 patients: clinicopathological and therapeutic features.

OBJECTIVE: To assess the clinicopathological and therapeutic features of patients with low (≥1000 to <10 000 Bühlmann Titre Units) (BTU), medium (10 000-70 000) or high (≥70 000) anti-myelin-associated glycoprotein (anti-MAG) antibody titres. METHODS: We retrospectively and prospectively analysed standardised report forms and medical records of 202 patients from 14 neuromuscular centres. RESULTS: Mean age at onset and mean time between symptom onset to last follow-up were respectively 62.6 years (25-91.4) and 8.4 years (0.3-33.3). Anti-MAG antibody titres at diagnosis were low, medium or high in 11%, 51% and 38% of patients. Patients presented with monoclonal gammopathy of undetermined significance in 68% of cases. About 17% of patients presented with 'atypical' clinical phenotype independently of anti-MAG titres, including acute or chronic sensorimotor polyradiculoneuropathies (12.4%), and asymmetric or multifocal neuropathy (3%). At the most severe disease stage, 22.4% of patients were significantly disabled. Seventy-eight per cent of patients received immunotherapies. Transient clinical worsening was observed in 12% of patients treated with rituximab (11/92). Stabilisation after rituximab treatment during the 7-12-month follow-up period was observed in 29% of patients. Clinical response to rituximab during the 6-month and/or 7-12-month follow-up period was observed in 31.5% of patients and correlated with anti-MAG titre ≥10 000 BTU. CONCLUSION: Our study highlights the extended clinical spectrum of patients with anti-MAG neuropathy, which appears unrelated to antibody titre. Besides, it may also suggest beneficial use of rituximab in the early phase of anti-MAG neuropathy.

Mutations in GFPT1-related congenital myasthenic syndromes are associated with synaptic morphological defects and underlie a tubular aggregate myopathy with synaptopathy.

Mutations in GFPT1 (glutamine-fructose-6-phosphate transaminase 1), a gene encoding an enzyme involved in glycosylation of ubiquitous proteins, cause a limb-girdle congenital myasthenic syndrome (LG-CMS) with tubular aggregates (TAs) characterized predominantly by affection of the proximal skeletal muscles and presence of highly organized and remodeled sarcoplasmic tubules in patients' muscle biopsies. We report here the first long-term clinical follow-up of 11 French individuals suffering from LG-CMS with TAs due to GFPT1 mutations, of which nine are new. Our retrospective clinical evaluation stresses an evolution toward a myopathic weakness that occurs concomitantly to ineffectiveness of usual CMS treatments. Analysis of neuromuscular biopsies from three unrelated individuals demonstrates that the maintenance of neuromuscular junctions (NMJs) is dramatically impaired with loss of post-synaptic junctional folds and evidence of denervation-reinnervation processes affecting the three main NMJ components. Moreover, molecular analyses of the human muscle biopsies confirm glycosylation defects of proteins with reduced O-glycosylation and show reduced sialylation of transmembrane proteins in extra-junctional area. Altogether, these results pave the way for understanding the etiology of this rare neuromuscular disorder that may be considered as a "tubular aggregates myopathy with synaptopathy".

Effect of enzyme replacement therapy with alglucosidase alfa (Myozyme®) in 12 patients with advanced late-onset Pompe disease.

BACKGROUND: The efficacy of enzyme replacement therapy (ERT) in patients at an advanced stage of Pompe disease has only been addressed in a few studies. Our objective was to assess the long term effects of ERT in a cohort of patients with severe Pompe disease. METHODS: We identified patients from the French Pompe Registry with severe respiratory failure and permanent wheelchair use (assisted walk for a few meters was allowed) when starting ERT. Patients' medical records were collected and reviewed and respiratory and motor functions, before ERT initiation and upon last evaluation were compared. RESULTS: Twelve patients (7 males) were identified. Median age at symptom onset was 24years [IQR=15.5; 36.0]. At baseline ventilation was invasive in 11 patients and noninvasive in one, with a median ventilation time of 24h [IQR=21.88; 24.00] (min 20; max 24). ERT was initiated at a median age of 52.5years [IQR=35.75; 66.50]. Median treatment duration was 55months [IQR=39.5; 81.0]. During observational period no adverse reaction to ERT was recorded, five patients (41.67%) died, three decreased their ventilation time by 30, 60 and 90min and two increased their assisted walking distance, by 80 and 20m. CONCLUSION: Some patients at a very advanced stage of Pompe disease may show a mild benefit from ERT, in terms of increased time of autonomous ventilation and of enlarged distance in assisted walk. ERT can be initiated in these patients in order to retain their current level of independence and ability to perform daily life activities.

Home care organization impacts patient management and survival in ALS.

OBJECTIVE: Progression of amyotrophic lateral sclerosis (ALS) depends on several factors linked to the disease. However, both the patient's living place and care organization role need to be evaluated. METHODS: We analysed the effect on survival of factors linked to ALS or the socio-geographical context in a prospective cohort of 203 patients followed between 2003 and 2011. RESULTS: Patients were 97 females and 106 males with a mean age of 65.5 years. Survival was longer in younger patients, in case of upper limb involvement, longer time to diagnosis, and initially higher forced vital capacity. Non-invasive positive pressure ventilation (NIPPV) and percutaneous gastrostomy (PEG) failed to demonstrate benefit. Patients who lived at home had longer survival. The nature of non-medical organization at home statistically influenced survival, which was longer with an organized network than with an unorganized one and shorter in absence of non-medical organization. In patients with indication of PEG and NIPPV, the proposition was statistically different according to the care givers. CONCLUSIONS: Besides the natural history of ALS, survival depended on home organization and the presence or the nature of a home-care system. Home organization was an important factor of decision for NIPPV and PEG proposals.

Fluxomic evidence for impaired contribution of short-chain acyl-CoA dehydrogenase to mitochondrial palmitate ß-oxidation in symptomatic patients with ACADS gene susceptibility variants.

BACKGROUND: Despite ACADS (acyl-CoA dehydrogenase, short-chain) gene susceptibility variants (c.511C>T and c.625G>A) are considered to be non-pathogenic, encoded proteins are known to exhibit altered kinetics. Whether or not, they might affect overall fatty acid ß-oxidation still remains, however, unclear. METHODS: De novo biosynthesis of acylcarnitines by whole blood samples incubated with deuterated palmitate (16-2H3,15-2H2-palmitate) is suitable as a fluxomic exploration to distinguish between normal and disrupted ß-oxidation, abnormal profiles and ratios of acylcarnitines with different chain-lengths being indicative of the site for enzymatic blockade. Determinations in 301 control subjects of ratios between deuterated butyrylcarnitine and sum of deuterated C2 to C14 acylcarnitines served here as reference values to state specifically functional SCAD impairment in patients addressed for clinical and/or biological suspicion of a ß-oxidation disorder. RESULTS: Functional SCAD impairment was found in 39 patients. The 27 patients accepting subsequent gene studies were all positive for ACADS mutations. Twenty-six of 27 patients were positive for c.625G>A variant. Twenty-three of 27 patients harbored susceptibility variants as sole ACADS alterations (18 homozygous and 3 heterozygous for c.625G>A, 2 compound heterozygous for c.625G>A/c.511C>T). CONCLUSION: Our present fluxomic assessment of SCAD suggests a link between ACADS susceptibility variants and abnormal ß-oxidation consistent with known altered kinetics of these variants.

A novel mutation of the C-terminal amino acid of FUS (Y526C) strengthens FUS gene as the most frequent genetic factor in aggressive juvenile ALS.

Although amyotrophic lateral sclerosis (ALS) typically occurs around 60 years, numerous publications report an onset of ALS before the age of 25 years that define juvenile ALS (jALS). Over the last decade, growing literature mentioned jALS with an aggressive evolution which are mainly linked to the FUS gene. We report here the case of a 25-year-old woman with a bulbar onset ALS that progressed in less than 12 months to invasive ventilation due to respiratory failure; Genetic screening identified a new mutation in the FUS gene that lies within the last codon. After reading the literature, it might be legitimate to consider that jALS linked to FUS mutations represent a specific entity different from both classical jALS and adult ALS linked to FUS gene. This should encourage clinician to firstly screen the FUS gene in the presence of a sporadic ALS that occurs before the age of 25 and with an aggressive profile of evolution.

Bent spine syndrome as the initial symptom of late-onset Pompe disease.

INTRODUCTION: Late-onset Pompe disease (LOPD) is a rare disorder characterized by progressive proximal muscle weakness and early respiratory insufficiency, for which enzyme replacement therapy (ERT) is available. METHODS: Having diagnosed a case of LOPD presenting with bent spine syndrome, we conducted a brief survey in the French centers involved in management of Pompe disease, from which we collected data on 3 other cases. RESULTS: The patients (3 women and 1 man) had a mean age of 64 years (range 51-77 years) and a delay in diagnosis of approximately 10 years (range 8-42 years). At diagnosis, 3 patients already had respiratory symptoms. All had normal or very mildly raised creatine kinase levels and magnetic resonance imaging abnormalities in the paraspinal muscles. They exhibited the most frequent mutation in Pompe disease (c.-32-13 T>G). CONCLUSION: Clinicians should be aware of this atypical presentation of LOPD to enable earlier diagnosis and treatment. Muscle Nerve 56: 167-170, 2017.

Incidence and predictors of sudden death, major conduction defects and sustained ventricular tachyarrhythmias in 1388 patients with myotonic dystrophy type 1.

AIMS: To describe the incidence and identify predictors of sudden death (SD), major conduction defects and sustained ventricular tachyarrhythmias (VTA) in myotonic dystrophy type 1 (DM1). METHODS AND RESULTS: We retrospectively enrolled 1388 adults with DM1 referred to six French medical centres between January 2000 and October 2013. We confirmed their vital status, classified all deaths, and determined the incidence of major conduction defects requiring permanent pacing and sustained VTA. We searched for predictors of overall survival, SD, major conduction defects, and sustained VTA by Cox regression analysis. Over a median 10-year follow-up, 253 (18.2%) patients died, 39 (3.6%) suddenly. Analysis of the cardiac rhythm at the time of the 39 SD revealed sustained VTA in 9, asystole in 5, complete atrioventricular block in 1 and electromechanical dissociation in two patients. Non-cardiac causes were identified in the five patients with SD who underwent autopsies. Major conduction defects developed in 143 (19.3%) and sustained VTA in 26 (2.3%) patients. By Cox regression analysis, age, family history of SD and left bundle branch block were independent predictors of SD, while age, male sex, electrocardiographic conduction abnormalities, syncope, and atrial fibrillation were independent predictors of major conduction defects; non-sustained VTA was the only predictor of sustained VTA. CONCLUSIONS: SD was a frequent mode of death in DM1, with multiple mechanisms involved. Major conduction defects were by far more frequent than sustained VTA, whose only independent predictor was a personal history of non-sustained VTA. ClinicalTrials.gov no: NCT01136330.

Punctate pattern: A promising imaging marker for the diagnosis of natalizumab-associated PML.

OBJECTIVE: To evaluate the usefulness of the punctate pattern (PP) for the diagnosis and follow-up of patients with progressive multifocal leukoencephalopathy (PML). METHODS: A cohort of 20 consecutive patients with PML, related to natalizumab (NTZ) (n = 14) or not (n = 6), underwent 3T MRI (147 MRI examinations). MRI was available at presymptomatic (n = 9 patients), symptomatic (n = 15), immune reconstitution inflammatory syndrome (IRIS), and chronic stages (n = 20). A pathologic control group of patients without PML (n = 80), with clinically definitive multiple sclerosis or a clinically isolated syndrome suggestive of CNS demyelination, underwent the same MRI protocol. Number and appearance of punctate lesions were assessed by 3 blinded readers using T2-weighted, fluid-attenuated inversion recovery (FLAIR), and postcontrast T1-weighted images. RESULTS: Interobserver agreement was good (κ = 0.79) (0.72-0.87). Of the 20 patients with PML, 18 had PP, including the 14 patients with NTZ-PML; none in the pathologic control group. Of the 9 presymptomatic patients with NTZ-PML, PP was observed in 7 (78% sensitive and 100% specific). Nonenhancing PP on T2-weighted/FLAIR images was detected in 13 patients with PML, exclusively at the presymptomatic or symptomatic stages (including 7 NTZ-PML), whereas enhancing PP occurred in 16 patients with PML, including 13 of the 14 patients with NTZ-PML at the IRIS stage. CONCLUSIONS: PP is a highly specific feature of PML and may be the first imaging feature at the presymptomatic stage with potential implications in patient care. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that a PP on MRI accurately identifies patients with NTZ-PML.

Punctate and curvilinear gadolinium enhancing lesions in the brain: a practical approach.

INTRODUCTION: Cerebral punctate and curvilinear gadolinium enhancements (PCGE) correspond to opacification of small vessel lumen or its perivascular areas in case of blood-brain barrier (BBB) disruption. We will discuss the possible causes of intra-parenchymal central nervous system PCGE. METHODS: Our review is based on French database including patients presenting with central nervous system PCGE and literature search using PubMed database with the following keywords: punctate enhancement, linear enhancement, and curvilinear enhancement. Disorders which displayed linear leptomeningeal or periventricular enhancements without intra-parenchymal PCGE are excluded of this review. RESULTS: Among our 39 patients with PCGE, 16 different diagnoses were established. After combining our PCGE causes with those described in the literature, we propose a practical approach. Besides physiologic post-contrast enhancement of small vessels, three pathologic conditions may exhibit PCGE: (1) small collateral artery network seen in Moyamoya syndrome, (2) small veins congestions related to developmental or acquired venous outflow disturbance, and (3) disorders causing small vessels BBB disruption indicated by T2 and FLAIR hyperintensities in the corresponding areas of PCGE. Disruption of the BBB could be caused by a direct injury of the endothelial cell, as in posterior reversible encephalopathy syndrome, Susac syndrome, and radiochemotherapy-induced injuries, or by an angiocentric cellular infiltrate, as in inflammatory disorders, demyelinating diseases, host immune responses fighting against infections, prelymphoma states, lymphoma, and in CLIPPERS. CONCLUSION: PCGE may conceal several causes, including physiological and pathological conditions. Nevertheless, a practical approach could improve its management and limit the indications of brain biopsy to very specific situations.

Sustained-released fampridine in multiple sclerosis: effects on gait parameters, arm function, fatigue, and quality of life.

Sustained-release fampridine (fampridine-SR) improves gait velocity and self-perceived capacities in people with multiple sclerosis (MS). However, little is known about the treatment's effect on temporospatial gait parameters, walking endurance, general fatigue, hand function and quality of life (QoL). We therefore sought to evaluate these parameters in a real-world setting: 120 consecutive, eligible patients with MS were evaluated at baseline (D0) and after two weeks (D14) of fampridine-SR. Lastly, D14 responders were again evaluated after three months (M3). Response to treatment was defined as a 15% improvement in at least one of the following tests: the Timed 25-Foot-Walk (T25FW), the 2-min walk test (2MWT) and the Multiple Sclerosis Walking Scale (MSWS-12). Eighty-three patients (74%) were found to be responders. The response rate was lower when assessed as a 20% improvement in the T25FW (50.9%), and this difference was particularly marked for fast-walking subjects (i.e. T25FW <8 s at baseline). Responders displayed mean improvements (at D14 and M3, respectively) of 34.5 and 35.5% in the T25FW, 39 and 36.7% in the 2MWT and 19 and 11.6% in the MSWS-12. The increase in gait velocity was due to both a higher cadence and a greater step length. Responders showed also significant, lasting reductions in fatigue (visual analogue scale and the Fatigue Severity Scale; p < 10(-4) at D14 and <0.01 at M3) and significant, lasting improvements in hand function (9 Hole Peg Test; p < 0.05) and QoL (SF-12; p < 0.01). In conclusion, several MS-induced symptoms other than gait velocity may be improved by fampridine-SR, even if this remains to be more specifically evaluated in future studies.

Distinctive Patterns of Transthyretin Amyloid in Salivary Tissue: A Clinicopathologic Study of 92 Patients With Amyloid-containing Minor Salivary Gland Biopsies.

Accurate typing of amyloidosis is still a major issue for pathologists and clinicians. Besides clinical data and immunohistochemistry, the histologic distribution of amyloid could represent a useful tool to prevent typing errors, such as the misdiagnosis of hereditary and senile amyloidosis as light chain-related amyloidosis (AL). Minor salivary gland biopsy (MSGB) is a widely performed procedure for amyloidosis diagnosis and typing. In the largest clinicopathologic series of amyloid-containing MSGB specimens to date, we investigated for the first time whether amyloidosis subtypes can be distinguished according to their pattern of salivary amyloid deposition. The histologic distribution and semiquantification of amyloid within salivary tissue were thoroughly reassessed for each case using Congo red-fluorescence. Clinical data were retrospectively collected. The cohort included 92 patients with amyloid-containing minor salivary gland biopsies. The type of amyloidosis was AL in 51 patients (55.4%), non-V30M mutant ATTR in 10 (10.9%), V30M mutant ATTR in 8 (8.7%), serum amyloid A-derived amyloidosis (AA) in 6 (6.5%), wild-type ATTR in 4 (4.3%), gelsolin in 3 (3.3%), and unclassified in 10 (10.9%). Amyloid was more abundant in AL and AA compared with ATTR amyloidosis, because of more extensive basement membranes and vascular deposits. Conversely, non-V30M mutant ATTR and wt-ATTR were strongly associated with peculiar amyloid nodules located in close contact with salivary excretory ducts, with a specificity of 91.7%. In conclusion, our study suggests for the first time that MSGB, in addition to its high sensitivity for amyloidosis diagnosis, is a simple and effective tool for the recognition of ATTR amyloidosis.