Thursday, March 2, 2017

Labrune syndrome

Courtesy of a colleague

Labrune P, Lacroix C, Goutières F, de Laveaucoupet J, Chevalier P, Zerah M, Husson B, Landrieu P. Extensive brain calcifications, leukodystrophy, and formation of parenchymal cysts: a new progressive disorder due to diffuse cerebral microangiopathy. Neurology. 1996 May;46(5):1297-301.

A new cerebral disorder, described in three unrelated children, has recognizable clinical, radiologic, and neuropathologic findings. The onset occurs from early infancy to adolescence with slowing of cognitive performance, rare convulsive seizures, and a mixture of extrapyramidal, cerebellar, and pyramidal signs. CT shows progressive calcifications in the basal and cerebellar gray nuclei and the central white matter. MRI reveals diffuse abnormal signals of the white matter on T2-weighted sequences. A special feature is the development of parenchymal cysts in the cerebellum and the supratentorial compartment, leading to compressive complications and surgical considerations. Neuropathologic examination of surgically removed pericystic samples reveals angiomatous-like rearrangements of the microvessels, together with degenerative secondary changes of other cellular elements. Both the anatomic findings and the course of the disease suggest a constitutional, diffuse cerebral microangiopathy resulting in microcystic, then macrocystic, parenchymal degeneration.

Nagae-Poetscher LM, Bibat G, Philippart M, Rosemberg S, Fatemi A, Lacerda MT, Costa MO, Kok F, Costa Leite C, Horská A, Barker PB, Naidu S. Leukoencephalopathy, cerebral calcifications, and cysts: new observations. Neurology. 2004 Apr 13;62(7):1206-9.

We describe three cases of the rare syndrome of leukoencephalopathy, brain calcifications, and cysts. Conventional MRI, proton spectroscopy, and diffusion-weighted imaging yielded additional information on the disease. Imaging findings favor increased water content rather than a demyelinating process in the pathophysiology of this disease. Clinical features of Coats disease and consanguinity were also encountered.

Jenkinson EM, Rodero MP, Kasher PR, Uggenti C, Oojageer A, Goosey LC, Rose Y, Kershaw CJ, Urquhart JE, Williams SG, Bhaskar SS, O'Sullivan J, Baerlocher GM, Haubitz M, Aubert G, Barañano KW, Barnicoat AJ, Battini R, Berger A, Blair EM, Brunstrom-Hernandez JE, Buckard JA, Cassiman DM, Caumes R, Cordelli DM, De Waele LM, Fay AJ, Ferreira P, Fletcher NA, Fryer AE, Goel H, Hemingway CA, Henneke M, Hughes I, Jefferson RJ, Kumar R, Lagae L, Landrieu PG, Lourenço CM, Malpas TJ, Mehta SG, Metz I, Naidu S, Õunap K, Panzer A, Prabhakar P, Quaghebeur G, Schiffmann R, Sherr EH, Sinnathuray KR, Soh C, Stewart HS, Stone J, Van Esch H, Van Mol CE, Vanderver A, Wakeling EL, Whitney A, Pavitt GD, Griffiths-Jones S, Rice GI, Revy P, van der Knaap MS, Livingston JH, O'Keefe RT, Crow YJ. Mutations in SNORD118 cause the cerebral microangiopathy leukoencephalopathy with calcifications and cysts. Nat Genet. 2016 Oct;48(10):1185-92.


Although ribosomes are ubiquitous and essential for life, recent data indicate that monogenic causes of ribosomal dysfunction can confer a remarkable degree of specificity in terms of human disease phenotype. Box C/D small nucleolar RNAs (snoRNAs) are evolutionarily conserved non-protein-coding RNAs involved in ribosome biogenesis. Here we show that biallelic mutations in the gene SNORD118, encoding the box C/D snoRNA U8, cause the cerebral microangiopathy leukoencephalopathy with calcifications and cysts (LCC), presenting at any age from early childhood to late adulthood. These mutations affect U8 expression, processing and protein binding and thus implicate U8 as essential in cerebral vascular homeostasis.

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