@article {910, title = {Pathogenic Variants in CEP85L Cause Sporadic and Familial Posterior Predominant Lissencephaly.}, journal = {Neuron}, volume = {106}, year = {2020}, month = {2020 04 22}, pages = {237-245.e8}, abstract = {

Lissencephaly (LIS), denoting a "smooth brain," is characterized by the absence of normal cerebral convolutions with abnormalities of cortical thickness. Pathogenic variants in over 20 genes are associated with LIS. The majority of posterior predominant LIS is caused by pathogenic variants in LIS1~(also known as PAFAH1B1), although a significant fraction remains without a known genetic etiology. We now implicate CEP85L as an important cause of~posterior predominant LIS, identifying 13 individuals with rare, heterozygous CEP85L variants, including 2 families with autosomal dominant inheritance. We show that CEP85L is a centrosome protein localizing to the pericentriolar material, and knockdown of Cep85l causes a neuronal migration defect in mice. LIS1 also localizes to the centrosome, suggesting that this organelle is key to the mechanism of posterior predominant LIS.

}, keywords = {Adolescent, Adult, Age of Onset, Animals, Centrosome, Child, Child, Preschool, Chromosome Aberrations, Classical Lissencephalies and Subcortical Band Heterotopias, Cytoskeletal Proteins, Female, Gene Knockdown Techniques, Genetic Variation, Heterozygote, Humans, Infant, Magnetic Resonance Imaging, Male, Mice, Mutation, Oncogene Proteins, Fusion, Pedigree, Seizures, Young Adult}, issn = {1097-4199}, doi = {10.1016/j.neuron.2020.01.027}, author = {Tsai, Meng-Han and Muir, Alison M and Wang, Won-Jing and Kang, Yi-Ning and Yang, Kun-Chuan and Chao, Nian-Hsin and Wu, Mei-Feng and Chang, Ying-Chao and Porter, Brenda E and Jansen, Laura A and Sebire, Guillaume and Deconinck, Nicolas and Fan, Wen-Lang and Su, Shih-Chi and Chung, Wen-Hung and Almanza Fuerte, Edith P and Mehaffey, Michele G and Ng, Ching-Ching and Chan, Chung-Kin and Lim, Kheng-Seang and Leventer, Richard J and Lockhart, Paul J and Riney, Kate and Damiano, John A and Hildebrand, Michael S and Mirzaa, Ghayda M and Dobyns, William B and Berkovic, Samuel F and Scheffer, Ingrid E and Tsai, Jin-Wu and Mefford, Heather C} } @article {582, title = {Cerebral hypomyelination associated with biallelic variants of FIG4.}, journal = {Hum Mutat}, volume = {40}, year = {2019}, month = {2019 05}, pages = {619-630}, abstract = {

The lipid phosphatase gene FIG4 is responsible for Yunis-Var{\'o}n syndrome and Charcot-Marie-Tooth disease Type 4J, a peripheral neuropathy. We now describe four families with FIG4 variants and prominent abnormalities of central nervous system (CNS) white matter (leukoencephalopathy), with onset in early childhood, ranging from severe hypomyelination to mild undermyelination, in addition to peripheral neuropathy. Affected individuals inherited biallelic FIG4 variants from heterozygous parents. Cultured fibroblasts exhibit enlarged vacuoles characteristic of FIG4 dysfunction. Two unrelated families segregate the same G > A variant in the +1 position of intron 21 in the homozygous state in one family and compound heterozygous in the other. This mutation in the splice donor site of exon 21 results in read-through from exon 20 into intron 20 and truncation of the final 115 C-terminal amino acids of FIG4, with retention of partial function. The observed CNS white matter disorder in these families is consistent with the myelination defects in the FIG4 null mouse and the known role of FIG4 in oligodendrocyte maturation. The families described here the expanded clinical spectrum of FIG4 deficiency to include leukoencephalopathy.

}, issn = {1098-1004}, doi = {10.1002/humu.23720}, author = {Lenk, Guy M and Berry, Ian R and Stutterd, Chloe A and Blyth, Moira and Green, Lydia and Vadlamani, Gayatri and Warren, Daniel and Craven, Ian and Fanjul-Fernandez, Miriam and Rodriguez-Casero, Victoria and Lockhart, Paul J and Vanderver, Adeline and Simons, Cas and Gibb, Susan and Sadedin, Simon and White, Susan M and Christodoulou, John and Skibina, Olga and Ruddle, Jonathan and Tan, Tiong Y and Leventer, Richard J and Livingston, John H and Meisler, Miriam H} } @article {728, title = {Pathogenic Variants in GPC4 Cause Keipert Syndrome.}, journal = {Am J Hum Genet}, volume = {104}, year = {2019}, month = {2019 May 02}, pages = {914-924}, abstract = {

Glypicans are a family of cell-surface heparan sulfate proteoglycans that regulate growth-factor signaling during development and are thought to play a role in the regulation of morphogenesis. Whole-exome sequencing of the Australian family that defined Keipert syndrome (nasodigitoacoustic syndrome) identified a hemizygous truncating variant in the gene encoding glypican 4 (GPC4). This variant, located in the final exon of GPC4, results in premature termination of the protein 51 amino acid residues prior to the stop codon, and in concomitant loss of functionally important N-linked glycosylation (Asn514) and glycosylphosphatidylinositol (GPI) anchor (Ser529) sites. We subsequently identified seven affected males from five additional kindreds with novel and predicted pathogenic variants in GPC4. Segregation analysis and X-inactivation studies in carrier females provided supportive evidence that the GPC4 variants caused the condition. Furthermore, functional studies of recombinant protein suggested that the truncated proteins p.Gln506 and p.Glu496 were less stable than the wild type. Clinical features of Keipert syndrome included a prominent forehead, a flat midface, hypertelorism, a broad nose, downturned corners of mouth, and digital abnormalities, whereas cognitive impairment and deafness were variable features. Studies of Gpc4 knockout mice showed evidence of the two primary features of Keipert syndrome: craniofacial abnormalities and digital abnormalities. Phylogenetic analysis demonstrated that GPC4 is most closely related to GPC6, which is associated with a bone dysplasia that has a phenotypic overlap with Keipert syndrome. Overall, we have shown that pathogenic variants in GPC4 cause a loss of function that results in Keipert syndrome, making GPC4 the third human glypican to be linked to a genetic syndrome.

}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2019.02.026}, author = {Amor, David J and Stephenson, Sarah E M and Mustapha, Mirna and Mensah, Martin A and Ockeloen, Charlotte W and Lee, Wei Shern and Tankard, Rick M and Phelan, Dean G and Shinawi, Marwan and de Brouwer, Arjan P M and Pfundt, Rolph and Dowling, Cari and Toler, Tomi L and Sutton, V Reid and Agolini, Emanuele and Rinelli, Martina and Capolino, Rossella and Martinelli, Diego and Zampino, Giuseppe and Dumi{\'c}, Miroslav and Reardon, William and Shaw-Smith, Charles and Leventer, Richard J and Delatycki, Martin B and Kleefstra, Tjitske and Mundlos, Stefan and Mortier, Geert and Bahlo, Melanie and Allen, Nicola J and Lockhart, Paul J} } @article {258, title = {Expanding the phenotypic spectrum of ARID1B-mediated disorders and identification of altered cell-cycle dynamics due to ARID1B haploinsufficiency.}, journal = {Orphanet J Rare Dis}, volume = {9}, year = {2014}, month = {2014 Mar 27}, pages = {43}, abstract = {

BACKGROUND: Mutations in genes encoding components of the Brahma-associated factor (BAF) chromatin remodeling complex have recently been shown to contribute to multiple syndromes characterised by developmental delay and intellectual disability. ARID1B mutations have been identified as the predominant cause of Coffin-Siris syndrome and have also been shown to be a frequent cause of nonsyndromic intellectual disability. Here, we investigate the molecular basis of a patient with an overlapping but distinctive phenotype of intellectual disability, plantar fat pads and facial dysmorphism.

METHODS/RESULTS: High density microarray analysis of the patient demonstrated a heterozygous deletion at 6q25.3, which resulted in the loss of four genes including AT Rich Interactive Domain 1B (ARID1B). Subsequent quantitative real-time PCR analysis revealed ARID1B haploinsufficiency in the patient. Analysis of both patient-derived and ARID1B knockdown fibroblasts after serum starvation demonstrated delayed cell cycle re-entry associated with reduced cell number in the S1 phase. Based on the patient{\textquoteright}s distinctive phenotype, we ascertained four additional patients and identified heterozygous de novo ARID1B frameshift or nonsense mutations in all of them.

CONCLUSIONS: This study broadens the spectrum of ARID1B associated phenotypes by describing a distinctive phenotype including plantar fat pads but lacking the hypertrichosis or fifth nail hypoplasia associated with Coffin-Siris syndrome. We present the first direct evidence in patient-derived cells that alterations in cell cycle contribute to the underlying pathogenesis of syndromes associated with ARID1B haploinsufficiency.

}, keywords = {Abnormalities, Multiple, Cell Cycle, Chromatin Assembly and Disassembly, DNA-Binding Proteins, Face, Female, Hand Deformities, Congenital, Haploinsufficiency, Humans, Intellectual Disability, Male, Micrognathism, Neck, Transcription Factors}, issn = {1750-1172}, doi = {10.1186/1750-1172-9-43}, author = {Sim, Joe C H and White, Susan M and Fitzpatrick, Elizabeth and Wilson, Gabrielle R and Gillies, Greta and Pope, Kate and Mountford, Hayley S and Torring, Pernille M and McKee, Shane and Vulto-van Silfhout, Anneke T and Jhangiani, Shalini N and Muzny, Donna M and Leventer, Richard J and Delatycki, Martin B and Amor, David J and Lockhart, Paul J} } @article {226, title = {Somatic mutations in cerebral cortical malformations.}, journal = {N Engl J Med}, volume = {371}, year = {2014}, month = {2014 Aug 21}, pages = {733-43}, abstract = {

BACKGROUND: Although there is increasing recognition of the role of somatic mutations in genetic disorders, the prevalence of somatic mutations in neurodevelopmental disease and the optimal techniques to detect somatic mosaicism have not been systematically evaluated.

METHODS: Using a customized panel of known and candidate genes associated with brain malformations, we applied targeted high-coverage sequencing (depth, >=200{\texttimes}) to leukocyte-derived DNA samples from 158 persons with brain malformations, including the double-cortex syndrome (subcortical band heterotopia, 30 persons), polymicrogyria with megalencephaly (20), periventricular nodular heterotopia (61), and pachygyria (47). We validated candidate mutations with the use of Sanger sequencing and, for variants present at unequal read depths, subcloning followed by colony sequencing.

RESULTS: Validated, causal mutations were found in 27 persons (17\%; range, 10 to 30\% for each phenotype). Mutations were somatic in 8 of the 27 (30\%), predominantly in persons with the double-cortex syndrome (in whom we found mutations in DCX and LIS1), persons with periventricular nodular heterotopia (FLNA), and persons with pachygyria (TUBB2B). Of the somatic mutations we detected, 5 (63\%) were undetectable with the use of traditional Sanger sequencing but were validated through subcloning and subsequent sequencing of the subcloned DNA. We found potentially causal mutations in the candidate genes DYNC1H1, KIF5C, and other kinesin genes in persons with pachygyria.

CONCLUSIONS: Targeted sequencing was found to be useful for detecting somatic mutations in patients with brain malformations. High-coverage sequencing panels provide an important complement to whole-exome and whole-genome sequencing in the evaluation of somatic mutations in neuropsychiatric disease. (Funded by the National Institute of Neurological Disorders and Stroke and others.).

}, keywords = {Cerebral Cortex, Classical Lissencephalies and Subcortical Band Heterotopias, DNA Mutational Analysis, Humans, Lissencephaly, Magnetic Resonance Imaging, Malformations of Cortical Development, Mutation, Periventricular Nodular Heterotopia}, issn = {1533-4406}, doi = {10.1056/NEJMoa1314432}, author = {Jamuar, Saumya S and Lam, Anh-Thu N and Kircher, Martin and D{\textquoteright}Gama, Alissa M and Wang, Jian and Barry, Brenda J and Zhang, Xiaochang and Hill, Robert Sean and Partlow, Jennifer N and Rozzo, Aldo and Servattalab, Sarah and Mehta, Bhaven K and Topcu, Meral and Amrom, Dina and Andermann, Eva and Dan, Bernard and Parrini, Elena and Guerrini, Renzo and Scheffer, Ingrid E and Berkovic, Samuel F and Leventer, Richard J and Shen, Yiping and Wu, Bai Lin and Barkovich, A James and Sahin, Mustafa and Chang, Bernard S and Bamshad, Michael and Nickerson, Deborah A and Shendure, Jay and Poduri, Annapurna and Yu, Timothy W and Walsh, Christopher A} }