1. Academic Validation
  2. Deficiency of asparagine synthetase causes congenital microcephaly and a progressive form of encephalopathy

Deficiency of asparagine synthetase causes congenital microcephaly and a progressive form of encephalopathy

  • Neuron. 2013 Oct 16;80(2):429-41. doi: 10.1016/j.neuron.2013.08.013.
Elizabeth K Ruzzo 1 José-Mario Capo-Chichi Bruria Ben-Zeev David Chitayat Hanqian Mao Andrea L Pappas Yuki Hitomi Yi-Fan Lu Xiaodi Yao Fadi F Hamdan Kimberly Pelak Haike Reznik-Wolf Ifat Bar-Joseph Danit Oz-Levi Dorit Lev Tally Lerman-Sagie Esther Leshinsky-Silver Yair Anikster Edna Ben-Asher Tsviya Olender Laurence Colleaux Jean-Claude Décarie Susan Blaser Brenda Banwell Rasesh B Joshi Xiao-Ping He Lysanne Patry Rachel J Silver Sylvia Dobrzeniecka Mohammad S Islam Abul Hasnat Mark E Samuels Dipendra K Aryal Ramona M Rodriguiz Yong-Hui Jiang William C Wetsel James O McNamara Guy A Rouleau Debra L Silver Doron Lancet Elon Pras Grant A Mitchell Jacques L Michaud David B Goldstein
Affiliations

Affiliation

  • 1 Center for Human Genome Variation, Duke University School of Medicine, Durham, NC 27708, USA.
Abstract

We analyzed four families that presented with a similar condition characterized by congenital microcephaly, intellectual disability, progressive cerebral atrophy, and intractable seizures. We show that recessive mutations in the ASNS gene are responsible for this syndrome. Two of the identified missense mutations dramatically reduce ASNS protein abundance, suggesting that the mutations cause loss of function. Hypomorphic Asns mutant mice have structural brain abnormalities, including enlarged ventricles and reduced cortical thickness, and show deficits in learning and memory mimicking aspects of the patient phenotype. ASNS encodes asparagine synthetase, which catalyzes the synthesis of asparagine from glutamine and aspartate. The neurological impairment resulting from ASNS deficiency may be explained by asparagine depletion in the brain or by accumulation of aspartate/glutamate leading to enhanced excitability and neuronal damage. Our study thus indicates that asparagine synthesis is essential for the development and function of the brain but not for that of other organs.

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