Gavrilova, Ralitza

Importance TMEM106B is a frontotemporal lobar degeneration (FTLD) genetic susceptibility factor, and TMEM106B protein aggregates are a feature of aging and neurodegeneration. Whether TMEM106B protein levels are associated with clinical features is unknown. Objective To investigate the clinical associations of cerebrospinal fluid (CSF) TMEM106B in FTLD. Design, Setting, and Participants This cross-sectional study was conducted in 2 independent frontotemporal dementia (FTD) cohorts (recruitment from April 2009 through July 2023, with analyses from January 2025 through April 2026), with a 2-year follow up. This multicenter clinical study integrated clinical, genetic, biomarker, and neuroimaging data. Individuals were recruited through the University of California, San Francisco (n = 3733), or ALLFTD (n = 2343). Participants with available CSF were included. A discovery cohort (n = 271) included participants with sporadic neuropathology-confirmed FTLD; presymptomatic or symptomatic carriers of pathogenic variants in C9orf72 , GRN , or MAPT ; or controls. An independent validation cohort (n = 383) included participants with clinically diagnosed sporadic FTD, Alzheimer disease (AD), and controls. Exposures CSF samples for TMEM106B quantification with aptamer proteomics (SomaScan version 3.0 [discovery cohort] and SomaScan version 4.1 [validation cohort]). Main Outcomes and Measures Parametric tests compared the primary outcome, CSF TMEM106B, by disease severity, TMEM106B rs1990622 genotype, sex, clinical syndrome, pathological diagnosis, and pathogenic variant and determined associations with brain volume. Results In the discovery (n = 271; 136 women [51%]; median [IQR] age, 59 [38-80] years) and validation (n = 383; 183 women [48%]; median [IQR] age, 64 [50-78] years) cohorts, lower CSF TMEM106B was associated with more severe disease (β, −0.15; 95% CI, −0.24 to −0.04; P = .003), lower frontotemporal brain volumes (β, 0.42; 95% CI, 0.24-0.61; P < .001), and faster clinical progression (β, −2.21; 95% CI, −3.70 to −0.72; P = .001). Associations of TMEM106B with clinical disease severity were independent of those with neurofilament light chain. TMEM106B levels were influenced by TMEM106B rs1990622 genotype, where individuals with the protective G/G genotype had lower levels than the risk A/A genotype. CSF TMEM106B levels did not differentiate between FTLD subtypes or between FTLD and AD. Conclusions and Relevance Per the results of this cross-sectional study, TMEM106B is detectable in CSF and levels reflect disease severity in sporadic and genetic FTLD and AD, but levels are also influenced by the TMEM106B rs1990622 genotype. CSF TMEM106B could support further studies to understand the mechanisms of disease and develop clinical tools in FTLD and other neurodegenerative diseases.

Abstract Genome sequencing of the heterogeneous primary mitochondrial disorders (PMD) frequently reveals variants of uncertain significance that require functional tests for diagnosis, and does not identify variants in all patients. We analyzed mitochondrial enzyme assays, blue native polyacrylamide gel electrophoresis (BN-PAGE) with in-gel activity staining, complex I assembly blot, and select protein abundances in fibroblasts of a case series of 204 PMD patients divided into functional classes, in comparison to 51 controls and 53 differential diagnostic conditions. Overall, sensitivity and specificity for respiratory chain enzyme assays were 46% and 93% respectively, for BN-PAGE 40% and 98%, for complex I assembly assay 49% and 99%. The overall sensitivity of all tests was 76%, specificity 93%, with positive predictive value 96% and negative predictive value 67%. Categories with high sensitivity were isolated complex deficiencies, nuclear DNA-encoded mitochondrial protein synthesis defects, co-factor defects, and mitochondrial amino-acyl-tRNA synthetase conditions when aided by protein abundance. Mitochondrial DNA mutations and maintenance disorders showed poor sensitivities. Secondary dysfunctions were rare. A complete battery of functional tests showed strong diagnostic clinical utility in fibroblasts. One sentence summary A combination of four mitochondrial functional tests to identify or confirm suspected primary mitochondrial disease in fibroblasts had good sensitivity and excellent specificity, well beyond what was perceived using enzyme assays only.

Abstract Disclosure: L.J. Plaza Enriquez: None. R. ibrahim: None. L. Ayari: None. R. Gavrilova: None. Y. Kudva: None. Introduction: Mitochondrial diabetes(mtDB) is a rare disease; hence its prevalence and associated comorbidities are not well defined. The aim of this study is to describe prevalence, glycemic control, treatment used for diabetes and comorbidities associated with this condition using a Mayo Clinic cohort of patients with mitochondrial mutations. Methods: We identified 23 patients with diabetes from an institutional cohort of patients with, mitochondrial mutations. Genetic mutations included the classic MTTL1 m.3243A>G in 22 of the patients and MTND5m.13513G>A in one patient. Statistical analysis was performed using BlueSky Statistics version 10.3.4 software. Categorical variables were compared using Fisher’s exact test and continuous variables were compared using ANOVA. Kaplan Meier survival curves were created. Unless otherwise stated, value of p of <0.05 was considered significant. Results: The cohort consisted of predominantly females (14 vs 9). The mean age at initial diabetes diagnosis was 39.5 years (CI: 30.6–48.4) for females and 32.0 years (CI: 20.9–43.1) for males (p = 0.253). Over 75% of patients were initially diagnosed with type 2 diabetes (T2D). The mean age at mtDB diagnosis was 51.7 years (SD 11.9) for females and 46.0 years (SD 8.5) for males, reflecting a >15-year gap between T2D and mtDB diagnosis. The mean BMI at initial diagnosis was similar between males and females (26.0 (CI: -8.4, 60.4)), though it was higher than the average reported in the literature. Most patients had multiple comorbidities associated with mtDB, including retinopathy, macular defects, cerebrovascular disease, CVD, arrhythmias, nephropathy, and gastrointestinal conditions. Retinopathy and macular defects typically developed within 5-10 years of diabetes diagnosis, while cerebrovascular disease and CVD had a later onset, at a mean of 8.25 years (SD = 6.76) and 5.0 years (SD = 5.75), respectively. However, the difference in onset times between these comorbidities was not statistically significant (p = 0.3228).Regarding glycemic control, there was no significant difference in HbA1c levels at diagnosis or later (HbA1c < 8% in >90% of the cohort). Various treatment modalities (13 on insulin therapy vs 10 on non-insulin treatments) did not show significant differences in glycemic control (p = 0.463), with mean HbA1c of 6.59 (SD 1.36). Mortality rates increased 10-15 years after initial diagnosis of mtDB, with 3 patients dying from complications related to the mitochondrial disorder. Conclusion: mtDB is associated with significant comorbidities/complications that developed earlier compared to T2D or even T1D from the literature. Initial misdiagnosis of this condition as T2D remains high. Different treatment modalities (insulin vs non-insulin) did not differ in glycemic control hence consideration as first options of treatment should be given to oral hypoglycemics. Presentation: Saturday, July 12, 2025

Abstract Objective Biallelic pathogenic MBOAT7 variants are associated with neurodevelopmental disorders, intellectual disability (ID), epilepsy, and neuropsychiatric disorders such as attention‐deficit/hyperactivity disorder and autism spectrum disorders. We aimed to characterize the epilepsy phenotype in a cohort of patients affected by this syndrome. Methods We describe epilepsy features, electroencephalography, magnetic resonance imaging (MRI) findings, antiseizure treatment response, and neurodevelopment of 15 patients with biallelic MBOAT7 variants. Results All 15 patients had ID or developmental delay (DD). Twelve suffered from epilepsy, with mean age at seizure onset of 36 months (range = 2 months–6.5 years) and 10 of 12 showing signs of DD before seizure onset. Patients with epilepsy presented with focal motor seizures with impaired awareness ( n = 3), focal tonic–clonic seizures and epileptic spasms ( n = 1), focal to bilateral tonic–clonic seizures ( n = 1), unknown onset bilateral tonic–clonic seizures ( n = 2), myoclonic seizures ( n = 4), myoclonic–atonic seizures ( n = 1), atonic seizures ( n = 1), tonic seizures ( n = 1), and myoclonic absences ( n = 2). Seizure freedom was achieved in 66.7% (8/12), with variable antiseizure treatment regimes. We reviewed electroencephalograms of the patients with epilepsy. Background activity was normal in 64%, whereas 36% had either a generalized or a focal slowing. Interictal epileptiform discharges (IEDs) were reported in 83%. Generalized spikes/polyspikes were found in 53%, multifocal IEDs in 23%, and parasagittal focal IEDs in 26%. The most frequent abnormal brain MRI findings, reported in 58% of patients, included high‐intensity signal in T2 and fluid‐attenuated inversion recovery (FLAIR) sequences in dentate nuclei and globus pallidus. Biallelic missense variants seemed to be associated with better cognitive and motor outcomes compared to truncating variants and in‐frame deletions. Significance Biallelic MBOAT7 variants are associated with global developmental impairment in all affected patients and epilepsy in the majority. The seizure semiology is heterogenous. One third of our cohort had persistent seizures despite treatment. The most frequent MRI findings were hyperintensities in T2/FLAIR sequences in dentate nuclei and globus pallidus.

Bi-allelic disruptive variants (nonsense, frameshift, and splicing variants) in KDM5B have been identified as causative for autosomal recessive intellectual developmental disorder type 65. In contrast, dominant variants, usually disruptive as well, have been more difficult to implicate in a specific phenotype, since some of them have been found in unaffected controls or relatives. Here, we describe individuals with likely pathogenic variants in KDM5B, including eight individuals with dominant missense variants. This study is a retrospective case series of 21 individuals with variants in KDM5B. We performed deep phenotyping and collected the clinical information and molecular data of these individuals’ family members. We compared the phenotypes according to variant type and to those previously described in the literature. The most common features were developmental delay, impaired intellectual development, behavioral problems, autistic behaviors, sleep disorders, facial dysmorphism, and overgrowth. DD, ASD behaviors, and sleep disorders were more common in individuals with dominant disruptive KDM5B variants, while individuals with dominant missense variants presented more frequently with renal and skin anomalies. This study extends our understanding of the KDM5B-related neurodevelopmental disorder and suggests the pathogenicity of certain dominant KDM5B missense variants.

Purpose To document the association of CAD-related disorder (EIEE-50) with cortical visual impairment. Observations An 8-month-old Caucasian boy with whole genome sequencing confirming 2 variants in the gene CAD, who presented with severe seizures, microcephaly, hyperreflexia, hypotonia, anemia, and severe cortical visual impairment. Magnetic resonance imaging (MRI) of the brain noted thickened cortical gray matter along the right calcarine fissure as well as changes suggesting malformation of cortical development. Empiric uridine monophosphate supplementation has significantly improved seizure activity, hypotonia, and development and has led to resolution of anemia. Conclusions and Importance CAD-related disorder is treatable and may affect visual cortical development causing severe secondary cortical visual impairment, a newly described clinical manifestation.