Your institution is subscribed to Read Institutional Edition. Log in or Sign Up to read full text articles.


Maple syrup urine disease: it has come a long way

D T Chuang
Journal of Pediatrics 1998, 132 (3 Pt 2): S17-23
Maple syrup urine disease (MSUD) was first described in 1954 by Menkes et al. as a progressive neurologic degenerative disorder. In 1960, Dancis et al. established that the metabolic block in MSUD is at the decarboxylation of branched-chain alpha-ketoacids derived from leucine, isoleucine, and valine. The multienzyme complex affected in MSUD, the mitrochondrial branched-chain alpha-ketoacid (BCKD) dehydrogenase complex was purified in 1978 to homogeneity in Reed's laboratory. This led to the later cloning of cDNAs and genes for subunits of the human BCKD complex. Genetic heterogeneity in MSUD is now explained by the various mutations that occur in the E1 alpha, E1 beta, E2, and E3 loci of the BCKD complex. Recently, we found that bacterial chaperonins GroEL and GroES promote folding and assembly of E1 decarboxylase component of the BCKD complex in Escherichia coli. Pulse-chase labeling in this system showed that a subset of E1 alpha mutations, notably the homozygous Y393N-alpha in Mennonite MSUD patients, impedes the assembly of the mutant E1 alpha subunit with normal E1 beta. The assembly defect is associated with a rapid degradation of the normal E1 beta subunit in MSUD cells. Retrovirus-mediated transduction of lymphoblasts from a Mennonite MSUD patient with a normal E1 alpha cDNA resulted in a complete restoration of BCKD activity. This was accompanied by a stabilization of the normal E1 beta subunit through assembly with recombinant E1 alpha. The results demonstrated the feasibility of stable correction of E1 alpha-deficient (type IA) MSUD and provided a basis for the development of gene therapy.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Trending Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"

We want to hear from doctors like you!

Take a second to answer a survey question.