Genet Med. 2024 Oct 10:101252. doi: 10.1016/j.gim.2024.101252. Online ahead of print. ABSTRACT PURPOSE: This study aimed to identify phenotypic factors associated with genetic diagnoses in patients with neurodevelopmental disorders and generate a decision tree to assist clinicians in identifying patients most likely to receive a positive result on genetic testing. METHODS: We retrospectively reviewed the charts of 316 patients evaluated in a neurodevelopmental clinic between 2014 and 2019. Patients were categorized based on genetic test results. Analyses were performed to identify variables that discriminate between patients with and without a genetic diagnosis. RESULTS: Patients with a genetic diagnosis were more likely to be female and have a history of motor delay, hypotonia, congenital heart disease, and early intervention. Classification and regression tree analysis revealed that 75% of patients with motor delay had a genetic diagnosis. In patients without motor delay, hypotonia, age of walking, and age at initial evaluation were important indicators of a genetic diagnosis. CONCLUSION: Our findings suggest that motor delay and hypotonia are associated with genetic diagnoses in children with neurodevelopmental disorders. The decision tree highlights patient subsets at greater risk and suggests possible phenotypic screens. Future studies could develop validated decision trees based on phenotypic data to assist clinicians in stratifying patients for genetic testing. PMID:39395029 | DOI:10.1016/j.gim.2024.101252

J Mol Neurosci. 2024 Oct 5;74(4):93. doi: 10.1007/s12031-024-02266-8. ABSTRACT Collagen VI-related dystrophies (COL6-RD) display a wide spectrum of disease severity and genetic variability ranging from mild Bethlem myopathy (BM) to severe Ullrich congenital muscular dystrophy (UCMD) and the intermediate severities in between with dual modes of inheritance, dominant and recessive. In the current study, next-generation sequencing demonstrated potential variants in the genes coding for the three alpha chains of collagen VI (COL6A1, COL6A2, or COL6A3) in a cohort of Egyptian patients with progressive muscle weakness (n = 23). Based on the age of disease onset and the patient clinical course, subjects were diagnosed as follows: 12 with UCMD, 8 with BM, and 3 with intermediate disease form. Fourteen pathogenic variants, including 5 novel alterations, were reported in the enrolled subjects. They included 3 missense, 3 frameshift, and 6 splicing variants in 4, 3, and 6 families, respectively. In addition, a nonsense variant in a single family and an inframe variant in 3 different families were also detected. Recessive and dominant modes of inheritance were recorded in 9 and 8 families, respectively. According to ACMG guidelines, variants were classified as pathogenic (n = 7), likely pathogenic (n = 4), or VUS (n = 3) with significant pathogenic potential. To our knowledge, the study provided the first report of the clinical and genetic findings of a cohort of Egyptian patients with collagen VI deficiency. Inter- and intra-familial clinical variability was evident among the study cohort. PMID:39367186 | DOI:10.1007/s12031-024-02266-8

Genet Med. 2024 Sep 20:101278. doi: 10.1016/j.gim.2024.101278. Online ahead of print. ABSTRACT PURPOSE: Biallelic INPP4A variants have recently been associated with severe neurodevelopmental disease in single case reports. Here, we expand and elucidate the clinical-genetic spectrum and provide a pathomechanistic explanation for genotype-phenotype correlations. METHODS: Clinical and genomic investigations of 30 individuals were undertaken alongside molecular and in silico modelling and translation reinitiation studies. RESULTS: We characterize a clinically variable disorder with cardinal features including global developmental delay, severe-profound intellectual disability, microcephaly, limb weakness, cerebellar signs and short stature. A more severe presentation associated with biallelic INPP4A variants downstream of exon 4 has additional features of (ponto)cerebellar hypoplasia, reduced cerebral volume, peripheral spasticity, contractures, intractable seizures and cortical visual impairment. Our studies identify the likely pathomechanism of this genotype-phenotype correlation entailing translational reinitiation in exon 4 resulting in an N-terminal truncated INPP4A protein retaining partial functionality, associated with less severe disease. We also identified identical reinitiation site conservation in Inpp4a-/- mouse models displaying similar genotype-phenotype correlation. Additionally, we show fibroblasts from a single affected individual exhibit disrupted endocytic trafficking pathways, indicating the potential biological basis of the condition. CONCLUSION: Our studies comprehensively characterise INPP4A-related neurodevelopmental disorder and suggest genotype-specific clinical assessment guidelines. We propose the potential mechanistic basis of observed genotype-phenotype correlations entails exon 4 translation reinitiation. PMID:39315527 | DOI:10.1016/j.gim.2024.101278

Genet Med. 2024 Sep 10:101251. doi: 10.1016/j.gim.2024.101251. Online ahead of print. ABSTRACT PURPOSE: This study aims to comprehensively delineate the phenotypic spectrum of ACTL6B-related disorders, previously associated with both autosomal recessive and autosomal dominant neurodevelopmental disorders. Molecularly, the role of the nucleolar protein ACTL6B in contributing to the disease has remained unclear. METHODS: We identified 105 affected individuals, including 39 previously reported cases, and systematically analysed detailed clinical and genetic data for all individuals. Additionally, we conducted knockdown experiments in neuronal cells to investigate the role of ACTL6B in ribosome biogenesis. RESULTS: Biallelic variants in ACTL6B are associated with severe-to-profound global developmental delay/intellectual disability (GDD/ID), infantile intractable seizures, absent speech, autistic features, dystonia, and increased lethality. De novo monoallelic variants result in moderate-to-severe GDD/ID, absent speech, and autistic features, while seizures and dystonia were less frequently observed. Dysmorphic facial features and brain abnormalities, including hypoplastic corpus callosum, parenchymal volume loss/atrophy, are common findings in both groups. We reveal that in the nucleolus, ACTL6B plays a crucial role in ribosome biogenesis, in particular in pre-rRNA processing. CONCLUSION: This study provides a comprehensive characterization of the clinical spectrum of both autosomal recessive and dominant forms of ACTL6B-associated disorders. It offers a comparative analysis of their respective phenotypes provides a plausible molecular explanation and suggests their inclusion within the expanding category of ‘ribosomopathies’. PMID:39275948 | DOI:10.1016/j.gim.2024.101251

JAMA Pediatr. 2024 Sep 9. doi: 10.1001/jamapediatrics.2024.3033. Online ahead of print. ABSTRACT IMPORTANCE: Sudden infant death syndrome (SIDS) is a major cause of infant death in the US. Previous research suggests that inborn errors of metabolism may contribute to SIDS, yet the relationship between SIDS and biomarkers of metabolism remains unclear. OBJECTIVE: To evaluate and model the association between routinely measured newborn metabolic markers and SIDS in combination with established risk factors for SIDS. DESIGN, SETTING, AND PARTICIPANTS: This was a case-control study nested within a retrospective cohort using data from the California Office of Statewide Health Planning and Development and the California Department of Public Health. The study population included infants born in California between 2005 and 2011 with full metabolic data collected as part of routine newborn screening (NBS). SIDS cases were matched to controls at a ratio of 1:4 by gestational age and birth weight z score. Matched data were split into training (2/3) and testing (1/3) subsets. Data were analyzed from January 2005 to December 2011. EXPOSURES: Metabolites measured by NBS and established risk factors for SIDS. MAIN OUTCOMES AND MEASURES: The primary outcome was SIDS. Logistic regression was used to evaluate the association between metabolic markers combined with known risk factors and SIDS. RESULTS: Of 2 276 578 eligible infants, 354 SIDS (0.016%) cases (mean [SD] gestational age, 38.3 [2.3] weeks; 220 male [62.1%]) and 1416 controls (mean [SD] gestational age, 38.3 [2.3] weeks; 723 male [51.1%]) were identified. In multivariable analysis, 14 NBS metabolites were significantly associated with SIDS in a univariate analysis: 17-hydroxyprogesterone, alanine, methionine, proline, tyrosine, valine, free carnitine, acetyl-L-carnitine, malonyl carnitine, glutarylcarnitine, lauroyl-L-carnitine, dodecenoylcarnitine, 3-hydroxytetradecanoylcarnitine, and linoleoylcarnitine. The area under the receiver operating characteristic curve for a 14-marker SIDS model, which included 8 metabolites, was 0.75 (95% CI, 0.72-0.79) in the training set and was 0.70 (95% CI, 0.65-0.76) in the test set. Of 32 infants in the test set with model-predicted probability greater than 0.5, a total of 20 (62.5%) had SIDS. These infants had 14.4 times the odds (95% CI, 6.0-34.5) of having SIDS compared with those with a model-predicted probability less than 0.1. CONCLUSIONS AND RELEVANCE: Results from this case-control study showed an association between aberrant metabolic analytes at birth and SIDS. These findings suggest that we may be able to identify infants at increased risk for SIDS soon after birth, which could inform further mechanistic research and clinical efforts focused on monitoring and prevention. PMID:39250160 | DOI:10.1001/jamapediatrics.2024.3033

Cancer Rep (Hoboken). 2024 Sep;7(9):e2119. doi: 10.1002/cnr2.2119. ABSTRACT BACKGROUND: Cancer predisposition syndromes (CPS) impact about 10% of patients with pediatric cancer. Genetic testing (CPS-GT) has multiple benefits, but few studies have described parent and child knowledge and attitudes regarding CPS-GT decision-making. This study examined parent and patient CPS-GT decision-making knowledge and attitudes. PROCEDURE: English- or Spanish-speaking parents of children with pediatric cancer and patients with pediatric cancer ages 15-18 within 12 months of diagnosis or relapse were eligible to participate. Seventy-five parents and 19 parent-patient dyads (N = 94 parents, 77.7% female, 43.6% Latino/a/Hispanic; 19 patients, 31.6% female) completed surveys measuring CPS-GT-related beliefs. Independent samples t-tests compared parent responses across sociodemographic characteristics and parent-patient responses within dyads. RESULTS: Spanish-speaking parents were significantly more likely than English-speaking parents to believe that CPS-GT not being helpful (p < .001) and possibly causing personal distress (p = .002) were important considerations for deciding whether to obtain CPS-GT. Parents with less than four-year university education, income less than $75,000, or Medicaid (vs. private insurance) were significantly more likely to endorse that CPS-GT not being helpful was an important consideration for deciding whether to obtain CPS-GT (p < .001). Parents felt more strongly than patients that they understood what CPS-GT was (p = .01) and that parents should decide whether patients under 18 should receive CPS-GT (p = .002). CONCLUSIONS: Spanish-speaking parents and parents with lower socioeconomic statuses were more strongly influenced by the potential disadvantages of CPS-GT in CPS-GT decision-making. Parents felt more strongly than patients that parents should make CPS-GT decisions. Future studies should investigate mechanisms behind these differences and how to best support CPS-GT knowledge and decision-making. PMID:39233650 | DOI:10.1002/cnr2.2119

EBioMedicine. 2024 Aug 26;107:105297. doi: 10.1016/j.ebiom.2024.105297. Online ahead of print. ABSTRACT BACKGROUND: NOTCH3 encodes a transmembrane receptor critical for vascular smooth muscle cell function. NOTCH3 variants are the leading cause of hereditary cerebral small vessel disease (SVD). While monoallelic cysteine-involving missense variants in NOTCH3 are well-studied in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), patients with biallelic variants in NOTCH3 are extremely rare and not well characterised. METHODS: In this study, we present clinical and genetic data from 25 patients with biallelic NOTCH3 variants and conduct a literature review of another 25 cases (50 patients in total). Brain magnetic resonance imaging (MRI) were analysed by expert neuroradiologists to better understand the phenotype associated with biallelic NOTCH3 variants. FINDINGS: Our systematic analyses verified distinct genotype-phenotype correlations for the two types of biallelic variants in NOTCH3. Biallelic loss-of-function variants (26 patients) lead to a neurodevelopmental disorder characterised by spasticity, childhood-onset stroke, and periatrial white matter volume loss resembling periventricular leukomalacia. Conversely, patients with biallelic cysteine-involving missense variants (24 patients) fall within CADASIL spectrum phenotype with early adulthood onset stroke, dementia, and deep white matter lesions without significant volume loss. White matter lesion volume is comparable between patients with biallelic cysteine-involving missense variants and individuals with CADASIL. Notably, monoallelic carriers of loss-of-function variants are predominantly asymptomatic, with only a few cases reporting nonspecific headaches. INTERPRETATION: We propose a NOTCH3-SVD classification depending on dosage and variant type. This study not only expands our knowledge of biallelic NOTCH3 variants but also provides valuable insight into the underlying mechanisms of the disease, contributing to a more comprehensive understanding of NOTCH3-related SVD. FUNDING: The Wellcome Trust, the MRC. PMID:39191170 | DOI:10.1016/j.ebiom.2024.105297

Nat Commun. 2024 Aug 22;15(1):7239. doi: 10.1038/s41467-024-51310-z. ABSTRACT Developmental and epileptic encephalopathies (DEEs) feature altered brain development, developmental delay and seizures, with seizures exacerbating developmental delay. Here we identify a cohort with biallelic variants in DENND5A, encoding a membrane trafficking protein, and develop animal models with phenotypes like the human syndrome. We demonstrate that DENND5A interacts with Pals1/MUPP1, components of the Crumbs apical polarity complex required for symmetrical division of neural progenitor cells. Human induced pluripotent stem cells lacking DENND5A fail to undergo symmetric cell division with an inherent propensity to differentiate into neurons. These phenotypes result from misalignment of the mitotic spindle in apical neural progenitors. Cells lacking DENND5A orient away from the proliferative apical domain surrounding the ventricles, biasing daughter cells towards a more fate-committed state, ultimately shortening the period of neurogenesis. This study provides a mechanism for DENND5A-related DEE that may be generalizable to other developmental conditions and provides variant-specific clinical information for physicians and families. PMID:39174524 | DOI:10.1038/s41467-024-51310-z

Nat Med. 2024 Aug 9. doi: 10.1038/s41591-024-03197-y. Online ahead of print. ABSTRACT KIF1A-associated neurological disorder (KAND) is a neurodegenerative and often lethal ultrarare disease with a wide phenotypic spectrum associated with largely heterozygous de novo missense variants in KIF1A. Antisense oligonucleotide treatments represent a promising approach for personalized treatments in ultrarare diseases. Here we report the case of one patient with a severe form of KAND characterized by refractory spells of behavioral arrest and carrying a p.Pro305Leu variant in KIF1A, who was treated with intrathecal injections of an allele-specific antisense oligonucleotide specifically designed to degrade the mRNA from the pathogenic allele. The first intrathecal administration was complicated by an epidural cerebrospinal fluid collection, which resolved spontaneously. Otherwise, the antisense oligonucleotide was safe and well tolerated over the 9-month treatment. Most outcome measures, including severity of the spells of behavioral arrest, number of falls and quality of life, improved. There was little change in the 6-min Walk Test distance, but qualitative changes in gait resulting in meaningful reductions in falls and increasing independence were observed. Cognitive performance was stable and did not degenerate over time. Our findings provide preliminary insights on the safety and efficacy of an allele-specific antisense oligonucleotide as a possible treatment for KAND. PMID:39122967 | DOI:10.1038/s41591-024-03197-y

Mov Disord. 2024 Aug 9. doi: 10.1002/mds.29905. Online ahead of print. ABSTRACT Acute presentation of severe motor disorders is a diagnostic and management challenge. We define severe acute motor exacerbations (SAME) as acute/subacute motor symptoms that persist for hours-to-days with a severity that compromise vital signs (temperature, breath, and heart rate) and bulbar function (swallowing/dysphagia). Phenomenology includes dystonia, choreoathetosis, combined movement disorders, weakness, and hemiplegic attacks. SAME can develop in diverse diseases and can be preceded by triggers or catabolic states. Recent descriptions of SAME in complex neurodevelopmental and epileptic encephalopathies have broadened appreciation of this presentation beyond inborn errors of metabolism. A high degree of clinical suspicion is required to identify appropriately targeted investigations and management. We conducted a comprehensive literature analysis of etiologies. Reported triggers are described and classified as per pathophysiological mechanism. A video of six cases displaying multiple SAME with diverse outcomes is provided. We identified 50 different conditions that manifest SAME, some associated with developmental regression. Etiologies include disorders of metabolism: energy substrate, amino acids, complex molecules, vitamins/cofactors, minerals, and neurotransmitters/synaptic vesicle cycling. Non-metabolic neurodegenerative and genetic disorders that present with movement disorders and epilepsy can additionally manifest SAME. A limited number of triggers are grouped here, together with an approach to investigations and general management strategies. Several neurogenetic and neurometabolic disorders manifest SAME. Identifying triggers can help in certain cases narrow the differential diagnosis and guide the expeditious application of targeted therapies to minimize adverse developmental and neurological consequences. This process may inform pathogenesis and eventually improve our understanding of the mechanisms that lead to the development of SAME. © 2024 International Parkinson and Movement Disorder Society. PMID:39119747 | DOI:10.1002/mds.29905