Two Novel Mutations in the BCKDK (Branched‐Chain Keto‐Acid Dehydrogenase Kinase) Gene Are Responsible for a Neurobehavioral Deficit in Two Pediatric Unrelated Patients. Issue 4 (5th March 2014)

• Record Type: Journal Article
• Authors: García‐Cazorla, Angels; Oyarzabal, Alfonso; Fort, Joana; Robles, Concepción; Castejón, Esperanza; Ruiz‐Sala, Pedro; Bodoy, Susanna; Merinero, Begoña; Lopez‐Sala, Anna; Dopazo, Joaquín; Nunes, Virginia; Ugarte, Magdalena; Artuch, Rafael; Palacín, Manuel; Rodríguez‐Pombo, Pilar; Alcaide, Patricia; Navarrete, Rosa; Sanz, Paloma; Font‐Llitjós, Mariona; Vilaseca, Ma Antonia; Ormaizabal, Aida; Pristoupilova, Anna; Agulló, Sergi Beltran
• Is Part Of: Human mutation. Volume 35:Issue 4(2014:Apr.)
• Page Start: 470
• Page End: 477
• Publication Date: 2014-03-05
• Subjects: Human chromosome abnormalities -- Periodicals; Mutation (Biology) -- Periodicals; 616.04205
• DOI: 10.1002/humu.22513
• Languages: English
• ISSNs: 1059-7794

Abstract

<abstract abstract-type="main"> <title>ABSTRACT</title> <p>Inactivating mutations in the <italic>BCKDK</italic> gene, which codes for the kinase responsible for the negative regulation of the branched‐chain α‐keto acid dehydrogenase complex (BCKD), have recently been associated with a form of autism in three families. In this work, two novel exonic <italic>BCKDK</italic> mutations, c.520C>G/p.R174G and c.1166T>C/p.L389P, were identified at the homozygous state in two unrelated children with persistently reduced body fluid levels of branched‐chain amino acids (BCAAs), developmental delay, microcephaly, and neurobehavioral abnormalities. Functional analysis of the mutations confirmed the missense character of the c.1166T>C change and showed a splicing defect r.[520c>g;521_543del]/p.R174Gfs1*, for c.520C>G due to the presence of a new donor splice site. Mutation p.L389P showed total loss of kinase activity. Moreover, patient‐derived fibroblasts showed undetectable (p.R174Gfs1*) or barely detectable (p.L389P) levels of BCKDK protein and its phosphorylated substrate (phospho‐E1α), resulting in increased BCKD activity and the very rapid BCAA catabolism manifested by the patients' clinical phenotype. Based on these results, a protein‐rich diet plus oral BCAA supplementation was implemented in the patient homozygous for p.R174Gfs1*. This treatment normalized plasma BCAA levels and improved growth, developmental and behavioral variables. Our results demonstrate that <italic>BCKDK</italic> mutations can result in neurobehavioral deficits in humans and support the rationale for dietary intervention.</p> </abstract>