Neurologic phenotypes associated with COL4A1/2 mutations

Objective: To characterize the neurologic phenotypes associated with COL4A1/2 mutations and to seek genotype–phenotype correlation. Methods: We analyzed clinical, EEG, and neuroimaging data of 44 new and 55 previously reported patients with COL4A1/COL4A2 mutations. Results: Childhood-onset focal seizures, frequently complicated by status epilepticus and resistance to antiepileptic drugs, was the most common phenotype. EEG typically showed focal epileptiform discharges in the context of other abnormalities, including generalized sharp waves or slowing. In 46.4% of new patients with focal seizures, porencephalic cysts on brain MRI colocalized with the area of the focal epileptiform discharges. In patients with porencephalic cysts, brain MRI frequently also showed extensive white matter abnormalities, consistent with the finding of diffuse cerebral disturbance on EEG. Notably, we also identified a subgroup of patients with epilepsy as their main clinical feature, in which brain MRI showed nonspecific findings, in particular periventricular leukoencephalopathy and ventricular asymmetry. Analysis of 15 pedigrees suggested a worsening of the severity of clinical phenotype in succeeding generations, particularly when maternally inherited. Mutations associated with epilepsy were spread across COL4A1 and a clear genotype–phenotype correlation did not emerge. Conclusion: COL4A1/COL4A2 mutations typically cause a severe neurologic condition and a broader spectrum of milder phenotypes, in which epilepsy is the predominant feature. Early identification of patients carrying COL4A1/COL4A2 mutations may have important clinical consequences, while for research efforts, omission from large-scale epilepsy sequencing studies of individuals with abnormalities on brain MRI may generate misleading estimates of the genetic contribution to the epilepsies overall

Effects of eight neuropsychiatric copy number variants on human brain structure

Many copy number variants (CNVs) confer risk for the same range of neurodevelopmental symptoms and psychiatric conditions including autism and schizophrenia. Yet, to date neuroimaging studies have typically been carried out one mutation at a time, showing that CNVs have large effects on brain anatomy. Here, we aimed to characterize and quantify the distinct brain morphometry effects and latent dimensions across 8 neuropsychiatric CNVs. We analyzed T1-weighted MRI data from clinically and non-clinically ascertained CNV carriers (deletion/duplication) at the 1q21.1 (n = 39/28), 16p11.2 (n = 87/78), 22q11.2 (n = 75/30), and 15q11.2 (n = 72/76) loci as well as 1296 non-carriers (controls). Case-control contrasts of all examined genomic loci demonstrated effects on brain anatomy, with deletions and duplications showing mirror effects at the global and regional levels. Although CNVs mainly showed distinct brain patterns, principal component analysis (PCA) loaded subsets of CNVs on two latent brain dimensions, which explained 32 and 29% of the variance of the 8 Cohen’s d maps. The cingulate gyrus, insula, supplementary motor cortex, and cerebellum were identified by PCA and multi-view pattern learning as top regions contributing to latent dimension shared across subsets of CNVs. The large proportion of distinct CNV effects on brain morphology may explain the small neuroimaging effect sizes reported in polygenic psychiatric conditions. Nevertheless, latent gene brain morphology dimensions will help subgroup the rapidly expanding landscape of neuropsychiatric variants and dissect the heterogeneity of idiopathic conditions

Germline and Mosaic Variants in PRKACA and PRKACB Cause a Multiple Congenital Malformation Syndrome

PRKACA and PRKACB code for two catalytic subunits (Cα and Cβ) of cAMP-dependent protein kinase (PKA), a pleiotropic holoenzyme that regulates numerous fundamental biological processes such as metabolism, development, memory, and immune response. We report seven unrelated individuals presenting with a multiple congenital malformation syndrome in whom we identified heterozygous germline or mosaic missense variants in PRKACA or PRKACB. Three affected individuals were found with the same PRKACA variant, and the other four had different PRKACB mutations. In most cases, the mutations arose de novo, and two individuals had offspring with the same condition. Nearly all affected individuals and their affected offspring shared an atrioventricular septal defect or a common atrium along with postaxial polydactyly. Additional features included skeletal abnormalities and ectodermal defects of variable severity in five individuals, cognitive deficit in two individuals, and various unusual tumors in one individual. We investigated the structural and functional consequences of the variants identified in PRKACA and PRKACB through the use of several computational and experimental approaches, and we found that they lead to PKA holoenzymes which are more sensitive to activation by cAMP than are the wild-type proteins. Furthermore, expression of PRKACA or PRKACB variants detected in the affected individuals inhibited hedgehog signaling in NIH 3T3 fibroblasts, thereby providing an underlying mechanism for the developmental defects observed in these cases. Our findings highlight the importance of both Cα and Cβ subunits of PKA during human development.This work was partially supported by funding from the Spanish Ministry of Science, Innovation and Universities (SAF2016-75434-R [AEI/FEDER, UE] and PID2019-105620RB-I00/AEI/10.13039/501100011033) to V.L.R.-P. S.S.T. was supported by NIH grant R03TR002947, E.M.F.M. by Kassel graduate school “Clocks”, and A.D.L. by the Italian Ministry of Health (RC-2019). The University of Antwerp supported G.M. and W.V.H. with Methusalem funding (FFB190208) and S.P. with a predoctoral grant. E.B. was supported by The Research Foundation Flanders with a postdoctoral grant (12A3814N). The study was also funded by a National Health and Medical Research Council Program Grant (1091593) to I.E.S., a Practitioner Fellowship (1006110) to I.E.S., a Senior Research Fellowship (1102971) to M.B., and an R.D. Wright Career Development Fellowship (1063799) to M.S.H. B.S.S. and G.L. were supported by Throne Holst Foundation UiO (2019-2021) and Strategic PhD fund by UiO/IMB

Data from: Neurologic phenotypes associated with COL4A1/2 mutations: expanding the spectrum of disease

Objective: To characterize the neurological phenotypes associated with COL4A1/2 mutations and to seek genotype-phenotype correlation. Methods We analyzed clinical, EEG and neuroimaging data of 44 new, and 55 previously reported patients with COL4A1/COL4A2 mutations. Results Childhood-onset focal seizures, frequently complicated by status epilepticus and resistance to anti-epileptic drugs, was the most common phenotype. EEG typically showed focal epileptiform discharges in the context of other abnormalities, including generalized sharp waves or slowing. In 46.4% of new patients with focal seizures, porencephalic cysts on brain MRI co-localized with the area of the focal epileptiform discharges. In patients with porencephalic cysts, brain MRI frequently also showed extensive white matter abnormalities, consistent with the finding of diffuse cerebral disturbance on EEG. Notably, we also identified a subgroup of patients with epilepsy as their main clinical feature, in which brain MRI showed non-specific findings, in particular periventricular leukoencephalopathy and ventricular asymmetry. Analysis of fifteen pedigrees suggested a worsening of the severity of clinical phenotype in succeeding generations, particularly when maternally inherited. Mutations associated with epilepsy were spread across COL4A1 and a clear genotype-phenotype correlation did not emerge. Conclusions COL4A1/COL4A2 mutations typically cause a severe neurological condition and a broader spectrum of milder phenotypes, in which epilepsy is the predominant feature. Early identification of patients carrying COL4A1/COL4A2 mutations may have important clinical consequences, whilst for research efforts, omission from large-scale epilepsy sequencing studies of individuals with abnormalities on brain MRI may generate misleading estimates of the genetic contribution to the epilepsies overall

Figure 5

Figure 5. Family pedigrees from published cases. Fig.5a. COL4A2 c. 2399 G>A; p. G800E. Ref. Ha et al., 2016. Fig.5b. COL4A2 c. 3455 G>A; p. G1152D. Ref. Yoneda et al., 2012. Fig.5c. COL4A1 c. 1249G>C; p.G417R. Ref. Giorgio et al., 2015. Fig.5d. COL4A1 c.3796G>C; p.G1266R. Ref. Shah et al., 2012. Fig.5e: COL4A1 c.2662G>C; p.G888R. Ref. Giorgio et al., 2015. Fig.5f: COL4A1 p.G562E. Ref. Vahedi et al., 2003 and Vahedi et al., 2007. Fig.5g.: COL4A1 p. G749S. Ref. Gasparini et al., 2006. Fig.5h: COL4A1 c.3389G>A; p.G1130D. Ref. Breedved et al. 2006 Fig.5i: COL4A1 c.2159G>A. Ref. Tonduti et al., 2012. Fig.5j: COL4A1 c.3715G>A; p.G1239R. Ref. Takenouchi et al., 2015. Fig.5k: COL4A1 c. 2645G>A. Ref. Shah et al., 2012. Fig.5l: COL4A1 c.1973 G>A. Ref. Livingston et al., 2011. Fig.5m: COL4A1 c.4031G>C; p.G1344A. Ref. Leung et al., 2012. Fig.5n: COL4A2 c.3455G>A; p.G1152D. Ref. Yoneda et al., 2012. Fig.5o: COL4A1 c.2085del; p. G696fs. Ref. Lemmens et al., 2013. wt/m: wild-type/mutated

Additional material

Table 1 summarizes the methods of identification of COL4A1/2 mutations in the cohort of new patients. Table 2 reports the phenotypes of previously-published patients with COL4A1/2 mutations and epilepsy. Tables 3a/b describes the clinical, EEG and brain MRI data of the new cohort of patients with COL4A1/2 mutations. Additional Method describes immunohistochemistry performed from consented surplus resected tissue from 1 case

Developmental trajectories of neuroanatomical alterations associated with the 16p11.2 Copy Number Variations

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