Abstract Background Pathogenic variants in WDR45 are associated with iron deposits in the basal ganglia. We aimed to determine iron levels in tears of patients with WDR45 X-linked optic atrophy compared to healthy controls. Methods The study group included two brothers aged 26 and 32 years and a 3-year-old girl from another family diagnosed with optic atrophy, all of whom harbored a novel pathogenic variant in WDR45. Tear samples were collected from the inferior fornix using Schirmer filter strips and analyzed for trace elements using a particle-induced X-ray emission (PIXE) technique and a Fast X123 SDD70 (C2) detector. Concentrations were calculated as the difference from unused Schirmer strips. Findings were compared with 28 healthy subjects, 21 females and 7 males, aged 18–50 years (mean 28.5 ± 9.09 years). Results All three patients with WDR45 X-linked optic atrophy exhibited elevated iron levels in their tears compared to healthy controls. No differences from the control group were detected for other trace elements. Conclusions This is the first study to show higher-than-normal iron levels in the tears of patients with X-linked optic atrophy due to a variant in WDR45. The findings broaden our understanding of the role of the WDR45 gene in disorders related to abnormal iron pathophysiology. PIXE analysis is a highly sensitive technique for measuring trace elements in tears. Further clinical studies are needed to investigate potentially novel genotype-phenotype correlations. The application of these findings in clinical practice may benefit patient care.

Clinical Implications In this large population-based cohort, FMF was associated with a higher prevalence of atopic disorders, not supporting a protective Th1-driven effect. Atopic comorbidity should be considered during routine clinical assessment and follow-up of patients with FMF.

CDK20, also known as CCRK, is a cyclin-dependent kinase that regulates cell growth, primary cilium structure, and Sonic Hedgehog signaling. CDK20 has not yet been associated with a known human disorder. In this report, we present a cohort of seven individuals from five unrelated families with bi-allelic variants in CDK20 and an overlapping phenotype of ventriculomegaly or hydrocephalus, midline brain anomalies, abnormal nose, midline cleft lip and/or palate, cryptophthalmos or anophthalmia, postaxial polydactyly, and a sandal toe gap. Immunoblot analysis of fibroblasts derived from two affected fetuses with a homozygous CDK20 c.687+6T>C (p.?) variant demonstrated reduced CDK20 levels. Fibroblasts derived from these affected fetuses were also significantly deficient in cilium formation and function, with abnormal cilium morphology and significantly decreased Hedgehog responsiveness. Our findings support that bi-allelic loss-of-function variants in CDK20 cause a severe ciliopathy with midline brain and facial anomalies.

Background: Variants in the ryanodine receptor 1 (RYR1) gene have been linked to a range of disorders, from congenital myopathy to adult-onset manifestations, with phenotypes varying from mild to severe. Methods: A retrospective review was conducted on an Israeli cohort of 36 individuals with RYR1 variants, identified through genetic testing as part of a national collaboration among multiple pediatric and adult neuromuscular clinics. Clinical features, molecular data, laboratory results, electromyographic findings, and muscle histology were analyzed. Each variant was classified according to its respective domain within the RYR1 gene. Results: Thirty-six cases were included in the analysis; 31 were from 11 unrelated families, and 5 were sporadic. Nine individuals were asymptomatic with normal CK levels. Most of the 27 affected patients presented with variable degrees of perinatal weakness, often accompanied by respiratory impairment or arthrogryposis. Weakness was predominantly proximal, with clinical courses that included deterioration, improvement, or stabilization. Three cases of King-Denborough syndrome were identified. Additional presentations included malignant hyperthermia and, in isolated cases, periodic paralysis. Muscle biopsies demonstrated considerable histologic heterogeneity, including fiber-size variation, internal nuclei, multiminicores, and fibrosis or dystrophic features. The pathogenic RYR1 variants included five compound-heterozygous genotypes, two homozygous variants, and two heterozygous variants. There was a positive correlation between variants located in the Bsol domain and disease severity. Conclusions: This cohort confirms and expands the clinical and histological diversity associated with RYR1 variants in Israel. Variants in the Bsol domain appear to be indicative of disease severity.

Inborn errors of selenoprotein expression arise from deleterious variants in genes encoding selenoproteins or selenoprotein biosynthetic factors, some of which are associated with neurodegenerative disorders. This study shows that bi-allelic selenocysteine tRNA-specific eukaryotic elongation factor (EEFSEC) variants cause selenoprotein deficiency, leading to progressive neurodegeneration. EEFSEC deficiency, an autosomal recessive disorder, manifests with global developmental delay, progressive spasticity, ataxia, and seizures. Cerebral MRI primarily demonstrated a cerebellar pathology, including hypoplasia and progressive atrophy. Exome or genome sequencing identified six different bi-allelic EEFSEC variants in nine individuals from eight unrelated families. These variants showed reduced EEFSEC function in vitro, leading to lower levels of selenoproteins in fibroblasts. In line with the clinical phenotype, an eEFSec-RNAi Drosophila model displays progressive impairment of motor function, which is reflected in the synaptic defects in this model organisms. This study identifies EEFSEC deficiency as an inborn error of selenocysteine metabolism. It reveals the pathophysiological mechanisms of neurodegeneration linked to selenoprotein metabolism, suggesting potential targeted therapies.

Short-read genome sequencing (GS) is a powerful technique for investigating the genetic etiologies of rare diseases, capturing diverse genetic variations that are challenging to approach with exome sequencing (ES). We performed GS on 260 families with intellectual disability/developmental delay. GS detected potentially disease-related variants in 55 of the 260 families, with structural resolution by long-read sequencing or optical genome mapping, and functional assessment by RNA sequencing. Excluding 31 theoretically ES-resolvable cases, GS yielded likely pathogenic variants in 17 of 229 as well as variants of unknown significance in 7 of 229, totaling 10.5%. These variants implicated several new etiological mechanisms: a microduplication syndrome involving ATP6V0C; disturbed interactions of TBL1XR1 and NR2F1 with putative cis-regulatory elements by chromosomal rearrangements; and a CCG repeat expansion near the CHD3 transcription start site. This study highlights the critical role of GS in clinical diagnostics and its potential to advance understanding of genetic disorders.

Phelan–McDermid syndrome (PMS) is a neurodevelopmental disorder, caused by haploinsufficiency of the SHANK3 gene. In addition to global developmental delay (GDD)/intellectual disability (ID) and autism spectrum disorder (ASD), PMS is characterized by multiple neurologic, behavioral and multisystemic manifestations. We aimed to establish a database of individuals with PMS in Israel. All participants underwent a detailed evaluation at a single medical center, and demographic, clinical, and genetic data were collected. Seventeen unrelated individuals with PMS (mean age 10 ± 8.2 years; range, 2.5–36 years) were enrolled (10 females, 59

Aim To examine the accuracy of prenatal counselling at a multidisciplinary fetal neurology clinic (FNC) that led to termination of pregnancy (TOP), to improve the quality of future consultations.Method This retrospective diagnostic cohort study compared the imaging (neurosonography and intrauterine magnetic resonance imaging) of fetuses evaluated at our FNC between 2009 and 2019, which underwent TOP because of brain anomalies, to the autopsy reports for concordance. The degrees of concordance were full, partial, and discordant.Results We identified 114 fetuses aborted because of brain anomalies, which underwent autopsy. All consultations were provided at the late stages of pregnancy, with 70% given in the third trimester and a mean gestational age of 29 weeks (range = 18-39, SD = 5). The imaging and autopsy results were fully or partially concordant in 96% of cases. Discordance was found in four fetuses, but termination was considered unjustified in only one. Microscopic evaluation of the fetal brain provided valuable information in 41% of fetuses and changed the diagnosis in 13%.Interpretation We found excellent concordance between the imaging and autopsy findings. We suggest that an autopsy is crucial for learning and delivering correct consultations to patients and planning their subsequent pregnancies.

The accurate removal of intronic sequences from pre-mRNA by the spliceosome is essential for correct gene expression, with small nuclear RNAs (snRNAs) such as U4 playing structural and regulatory roles in catalyzing this. De novo variants in the highly constrained critical region including the T-loop region of RNU4-2 have been linked to ReNU syndrome, a neurodevelopmental disorder, but the broader mutational spectrum remains uncharacterized. Here, we show that, in a cohort of unresolved cases with neurodevelopmental disorder, monoallelic and biallelic RNU4-2 variants were identified in 16 affected individuals, expanding the genetic basis beyond the critical region: 12 with de novo T-loop variants and 4 from two families with compound heterozygous variants in non-critical regions (stem II, the k-turn, and the Sm-binding site). Previously reported functional mapping by saturation genome editing confirmed that most of the variant positions in this study are highly functionally constrained. Clinically, individuals with biallelic variants exhibited developmental delay and intellectual disability that were similar to but milder than those with monoallelic variants, notably lacking extracerebral organ involvement. These results suggest that pathogenic RNU4-2 variants act in both dominant and recessive manners, and that non-critical regions may also harbor disease-causing variants. More broadly, this study underscores the diagnostic importance of non-coding RNA genes in neurodevelopmental disorders and demonstrates the need to distinguish pathogenic variants from benign ones, together with their inheritance patterns.

AIM:To evaluate the role of parental magnetic resonance imaging (MRI) in assessing fetuses with suspected brain anomalies and its use in prenatal counselling. METHOD:A retrospective, multicentre chart review was conducted on fetuses who underwent brain MRI because of suspected brain abnormalities between January 2008 and December 2022, with one or both parents who underwent brain MRI (MRI-Trio) as part of prenatal counselling. Clinical and demographic data were collected, including fetal and parental MRI findings, prenatal counselling outcomes, genetic testing results, family and previous pregnancy history, neurological examinations of the born children up to 24 months of age, and autopsy reports of fetuses from terminated pregnancies. MRI-Trio concordance was defined as at least one abnormal brain feature identified with similarity in the fetus and the parents. The live-born children were assessed postnatally through either neurodevelopmental evaluations or telephone interviews. RESULTS:Sixty pregnancies were included (41.7% with concordant and 58.3% with discordant MRI-Trio). Forty-two children were born (70%) and 17 pregnancies were terminated (28.3%). One case of in utero fetal death (1.7%) was reported. The most common brain findings were multiple anomalies (n = 26, 43.3%), isolated disorders of the corpus callosum (n = 17, 28.3%), atypical periventricular pseudocysts (n = 6, 10%), and anomalies of the anterior complex (n = 4, 6.7%). MRI-Trio enabled better prognostication. When MRI-Trio was concordant, counselling was more favourable (n = 22, 36.6%) and the majority of live-born children exhibited typical development (p < 0.001). INTERPRETATION:MRI-Trio is a valuable tool for identifying dominantly inherited brain anomalies that may not hold developmental significance or are associated with favourable outcomes, acknowledging the potential for variable penetrance, which may result in more severe presentations. Concordant MRI-Trio findings can enhance the accuracy of prenatal counselling, potentially reducing the incidence of termination of pregnancy.

We describe 2 families with 5 members from 2 generations whose clinical and laboratory characteristics over up to 15 years were consistent with dysglycemia/impaired glucose tolerance. In both families (2 probands and 3 family members), long-term follow-up excluded diabetes type 1 and type 2. Diabetes type 1 antibodies were persistently negative and C-peptide levels were normal. In Family 1, the proband, during a follow-up of 7 years (10.3-17.5 years of age), exhibited persistently high HbA1c (>5.7%) with fasting blood glucose levels mostly higher than 100 mg/dl and postprandial glucose levels up to 180 mg/dl. She eventually required oral anti-diabetics with an improvement in glycemic balance. The father and sister also had persistent mild hyperglycemia with borderline high HbA1c (mostly > 5.7%) levels over 15 and 6.2 years respectively. In Family 2, the proband exhibited borderline high fasting hyperglycemia (>100 mg/dl) at age 16.2 years with increasing HbA1c levels (from 5.6%–5.9%) and impaired glucose tolerance at age 18.3 years (2 h blood glucose 156 mg/dl after 75 g glucose). His sister also exhibited borderline hyperglycemia with borderline high HbA1c over 2 years (13.6-15.4 years). These subjects shared a unique phenotype. They are tall and slim with decreased BMI. Three subjects from Generation II failed to thrive during infancy. In view of the data from 2 generations suggesting maturity-onset diabetes of the young (MODY) with autosomal dominant inheritance, we sought to analyze the MODY genes. In Family 1, the molecular analysis by the MODY panel including 11 genes and whole exome sequencing did not detect any mutation in the proband. In Family 2, the MODY panel was also negative in the proband’s sister. These families may represent a hitherto unidentified syndrome. Unique features described in this report may help to reveal additional families with similar characteristics and to decipher the molecular basis of this syndrome. In selected cases, oral antidiabetics in adolescents may improve the glycemic balance.

Microcephaly is a sign, not a diagnosis. Its incidence varies widely due to the differences in the definition and the population being studied. It is strongly related to neurodevelopmental disorders. Differences in definitions and measurement techniques between fetuses and newborns pose a great challenge for the diagnosis and prognostication of fetal microcephaly. A false positive diagnosis can result (in countries where it is legal) in erroneous termination of pregnancy, where a false negative diagnosis might lead to the birth of a microcephalic newborn. Microcephaly in growth restricted fetuses deserves special attention and separate evaluation as it is an important prognostic factor, and not necessarily part of the general growth retardation. Several genetic syndromes incorporating microcephaly and intrauterine growth retardation (IUGR) are discussed. Deceleration of the head circumference (HC) growth rate even when the HC is still within normal limits might be the only clue for developing microcephaly and should be considered during fetal head growth follow up. Combining additional parameters such as a positive family history, associated anomalies, and new measurement parameters can improve prediction in about 50% of cases, and thus should be part of the prenatal workup. Advances in imaging modalities and in prenatal genetic investigation along with the emergence of new growth charts can also improve diagnostic accuracy. In this article, we review the different definitions and etiologies of fetal microcephaly, discuss difficulties in diagnosis, investigate the reasons for the low yield of prenatal diagnosis, and provide improvement suggestions. Finally, we suggest an updated algorithm that will aid in the diagnosis and management of fetal microcephaly.

The biallelic variants of the POP1 gene are associated with the anauxetic dysplasia (AAD OMIM 607095), a rare skeletal dysplasia, characterized by prenatal rhizomelic shortening of limbs and generalized joint hypermobility. Affected individuals usually have normal neurodevelopmental milestones. Here we present three cases from the same family with likely pathogenic homozygous POP1 variant and a completely novel phenotype: a girl with global developmental delay and autism, microcephaly, peculiar dysmorphic features and multiple congenital anomalies. Two subsequent pregnancies were terminated due to multiple congenital malformations. Fetal DNA samples revealed the same homozygous variant in the POP1 gene. Expression of the RMRP was reduced in the proband compared with control and slightly reduced in both heterozygous parents, carriers for this variant. To our knowledge, this is the first report of this new phenotype, associated with a novel likely pathogenic variant in POP1. Our findings expand the phenotypic spectrum of POP1-related disorders.

There are scarce reports of riboflavin-responsive lipid storage myopathy in elderly patients with onset in their sixties. We describe three elderly patients with riboflavin-responsive lipid-storage myopathy. All three patients (aged 67-71 years on first examination) had subacute onset of neck extensors and proximal limb weakness progressing to inability to rise from a sitting position or to walk. Muscle biopsies showed vacuoles with lipid content, mainly in type 1 fibers. Genetic analysis failed to identify any pathogenic variant in one patient, identified a heterozygous variant of uncertain significance c.812 A > G; p.Tyr271Cys in the ETFDH gene in the second patient, and revealed a heterozygote likely pathogenic variant c.1286-2 A > C in the ETFDH gene pre-dicted to cause abnormal splicing in the third patient. All patients responded to treatment with riboflavin and carnitine, and regained normal strength. This report emphasizes the importance of muscle biopsy in revealing treatable lipid storage myopathy in elderly patients with progressive myopathy of unidentifiable cause.

ObjectiveTo develop novel fetal reference ranges for the characterization of the normal appearance of the Sylvian fissures (SF) along gestation and to apply them to fetuses with cortical abnormalities affecting the SF. MethodsIn this cross-sectional study, we used three-dimensional sonographic multiplanar reformatting (3D-MPR) to examine the fetal SF. Normal development was assessed in the second and third trimesters. SF parameters were evaluated in predefined axial and coronal planes: insular height and length, SF depth, and the extent of the coverage of the insula by the frontal and temporal lobes. Intra-observer variability and inter-rater reliability for the studied parameters were evaluated. The new reference charts were applied to 19 fetuses with cortical abnormalities involving the SF who had appropriate sonographic volumes for 3D-MPR analysis. Their diagnoses were confirmed by autopsy, fetal or postnatal MRI, genetic findings related to cortical malformations, or an abnormal cortical imaging pattern with similar MRI findings in an affected sibling. We applied the two previously published references for the evaluation of fetal SF development to these cases and compared the ability of the references to correctly detect SF abnormalities. ResultsThe study included 189 fetuses of low-risk singleton pregnancies between 24 and 34 gestational weeks. The insular length or height increased with gestational age in the axial and coronal planes with adjusted R-2 = 0.621, p R-2 = 0.384, p < 0.0001, respectively. The SF depth also increased with gestational age in the axial and coronal planes with adjusted R-2 = 0.695, p R-2 = 0.219, p = 0.008, respectively. The extent of the coverage of the insula by the frontal and temporal lobes in the coronal plane increased with gestational age (adjusted R-2 = 0.627, p R-2 = 0.589, p < 0.0001, respectively). The interclass correlation coefficients of the intra- and inter-rater reliability of the studied parameters ranged between 0.71 and 0.97. The cortical anomalies in the 19 fetuses were polymicrogyria (7), simplified gyral pattern (3), dysgyria (3), lissencephaly (2), cortical malformation related to tubulinopathy (1), brain atrophy (1), cortical dysplasia (1), and cobblestone malformation (1). Three of the fetuses had multiple cortical anomalies. In 17 of 19 (89%) cases, at least one of our 6 SF parameters was found to be out of the normal range. In the coronal plane, SF height and depth were measured below 2SD in 9 (47%) and 4 (21%) cases, respectively. In the axial plane, SF length and depth were out of the normal ranges in six (31.5%) and four (21%), correspondingly. In the coronal plane, the opercular coverage by the frontal and temporal lobes was below 2 SD in 10 (52%) and 11 (57%), respectively. The scoring of the SF operculization by Quarello et al. was abnormal in 8 cases (42%). The measurement of the SF angle according to Poon et al. was abnormal in 14 cases (74%). ConclusionsThe fetal SF is a complex developing structure that can be reliably characterized by sonographic parameters. One abnormal parameter is sufficient to raise the suspicion of SF malformation. Our new SF parameters might facilitate the detection of prenatal cortical abnormalities affecting the SF.

BACKGROUND AND PURPOSE:Medullary tegmental cap dysplasia is a rare brainstem malformation, first described and defined by James Barkovich in his book Pediatric Neuroimaging from 2005 as an anomalous mass protruding from the posterior medullary surface. We describe the neuroimaging, clinical, postmortem, and genetic findings defining this unique malformation.MATERIALS AND METHODS:This is a multicenter, international, retrospective study. We assessed the patients' medical records, prenatal ultrasounds, MR images, genetic findings, and postmortem results. We reviewed the medical literature for all studies depicting medullary malformations and evaluated cases in which a dorsal medullary protuberance was described.RESULTS:We collected 13 patients: 3 fetuses and 10 children. The medullary caps had multiple characteristics. Associated brain findings were a rotated position of the medulla, a small and flat pons, cerebellar anomalies, a molar tooth sign, and agenesis of the corpus callosum. Systemic findings included the following: polydactyly, hallux valgus, large ears, and coarse facies. Postmortem analysis in 3 patients revealed that the cap contained either neurons or white matter tracts. We found 8 publications describing a dorsal medullary protuberance in 27 patients. The syndromic diagnosis was Joubert-Boltshauser syndrome in 11 and fibrodysplasia ossificans progressiva in 14 patients.CONCLUSIONS:This is the first study to describe a series of 13 patients with medullary tegmental cap dysplasia. The cap has different shapes: distinct in Joubert-Boltshauser syndrome and fibrodysplasia ossificans progressive. Due to the variations in the clinical, imaging, and postmortem findings, we conclude that there are multiple etiologies and pathophysiology. We suggest that in some patients, the pathophysiology might be abnormal axonal guidance.

The fetal neurology clinic (FNC) is a multidisciplinary clinic that utilises the advancements in prenatal imaging (US and MRI) and genetic testing to identify brain anomalies and prognosticate the neurodevelopmental outcome of fetuses to provide consultation to couples regarding pregnancy management in cases with suspected severe outcomes. In high-risk cases, termination of pregnancy (TOP) is permitted according to the law. Only a few studies compared the concordance between prenatal imaging and the autopsy report; most were done in the early stages of pregnancy. A retrospective cohort in which pathology reports were compared to imaging studies in all fetuses screened in our fetal neurology clinic and underwent TOP due to brain anomaly between 2009 and 2019. The rate of concordance was rated on a scale. We identified 113 cases of TOP due to brain malformations. All consultations were given from the second trimester onward and most in the third trimester. We found an agreement in 94% of cases: Full agreement was found in 56% and partial in 38%. In the partial agreement group, in 80% of the cases, the autopsy added information that would not have changed the final consultation. Disagreement between the imaging and the autopsy results was seen in only 8 cases. In 6 of them, the TOP was justified, and in only 2 cases, the TOP was unjustified. This is the largest study comparing pathology findings to prenatal imaging in fetuses screened in the advanced stages of pregnancy. We found high agreement rates between the imaging and the autopsy findings, and even in cases of disagreement, TOP was justified in most of them. The autopsy report added valuable information that enabled more accurate consultation. Despite the high concordance rate in our study, we conclude that the postmortem examination is of great significance. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Purpose: Pathogenic variants in genes involved in the epigenetic machinery are an emerging cause of neurodevelopment disorders (NDDs). Lysine-demethylase 2B (KDM2B) encodes an epigenetic regulator and mouse models suggest an important role during development. We set out to determine whether KDM2B variants are associated with NDD.Methods: Through international collaborations, we collected data on individuals with hetero-zygous KDM2B variants. We applied methylation arrays on peripheral blood DNA samples to determine a KDM2B associated epigenetic signature.Results: We recruited a total of 27 individuals with heterozygous variants in KDM2B. We present evidence, including a shared epigenetic signature, to support a pathogenic classification of 15 KDM2B variants and identify the CxxC domain as a mutational hotspot. Both loss-of -function and CxxC-domain missense variants present with a specific subepisignature. Moreover, the KDM2B episignature was identified in the context of a dual molecular diagnosis in multiple individuals. Our efforts resulted in a cohort of 21 individuals with heterozygous (likely) pathogenic variants. Individuals in this cohort present with developmental delay and/or intellectual disability; autism; attention deficit disorder/attention deficit hyperactivity disorder; congenital organ anomalies mainly of the heart, eyes, and urogenital system; and subtle facial dysmorphism.Conclusion: Pathogenic heterozygous variants in KDM2B are associated with NDD and a specific epigenetic signature detectable in peripheral blood.(c) 2022 The Authors. Published by Elsevier Inc. on behalf of American College of Medical Genetics and Genomics. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

BACKGROUND:Leukodystrophies are monogenic disorders primarily affecting the white matter. We aimed to evaluate the utility of genetic testing and time-to-diagnosis in a retrospective cohort of children with suspected leukodystrophy. METHODS:Medical records of patients who attended the leukodystrophy clinic at the Dana-Dwek Children's Hospital between June 2019 and December 2021 were retrieved. Clinical, molecular, and neuroimaging data were reviewed, and the diagnostic yield was compared across genetic tests. RESULTS:Sixty-seven patients (Female/Male ratio 35/32) were included. Median age at symptom onset was 9 months (interquartile range (IQR) 3-18 months), and median length of follow-up was 4.75 years (IQR 3-8.5). Time from symptom onset to a confirmed genetic diagnosis was 15months (IQR 11-30). Pathogenic variants were identified in 60/67 (89.6%) patients; classic leukodystrophy (55/67, 82.1%), leukodystrophy mimics (5/67, 7.5%). Seven patients (10.4%) remained undiagnosed. Exome sequencing showed the highest diagnostic yield (34/41, 82.9%), followed by single-gene sequencing (13/24, 54%), targeted panels (3/9, 33.3%) and chromosomal microarray (2/25, 8%). Familial pathogenic variant testing confirmed the diagnosis in 7/7 patients. A comparison between patients who presented before (n = 31) and after (n = 21) next-generation sequencing (NGS) became clinically available in Israel revealed that the time-to-diagnosis was shorter in the latter group with a median of 12months (IQR 3.5-18.5) vs. a median of 19 months (IQR 13-51) (p = 0.005). CONCLUSIONS:NGS carries the highest diagnostic yield in children with suspected leukodystrophy. Access to advanced sequencing technologies accelerates speed to diagnosis, which is increasingly crucial as targeted treatments become available.