Mulibrey nanism is an autosomal recessive prenatal-onset growth disorder of 
unknown pathogenesis. The main clinical features are pre- and postnatal growth 
failure, characteristic dysmorphic craniofacial features, heart disease, and 
hepatomegaly. Five truncating mutations in the TRIM37 gene have previously been 
reported in Mulibrey nanism patients. The TRIM37 protein encodes a novel protein 
of unknown function. It contains a tripartite motif (TRIM, also denoted the 
RING-B-box-Coiled-coil or RBCC domain) and a TRAF (tumor necrosis 
factor-receptor associated factor) domain. TRIM37 localizes to peroxisomes 
classifying Mulibrey nanism as a peroxisomal disorder. Here we have 
characterized the genomic structure of the TRIM37 gene, which has 24 exons 
spanning approximately 109 kb of genomic DNA. Further, we report six novel 
disease-associated mutations, five of which predict a truncated protein: 
c.745C>T (p.Gln249X), c.1411C>T (p.Arg471X), c.2056C>T (p.Arg686X), and an 8.6 
kb genomic deletion (c.1314+507_1668-207del resulting in p.Arg439fsX4). The 
sixth mutation (c.965G>T) is the first missense mutation (p.Gly322Val) 
associated with Mulibrey nanism. It affects the TRAF domain of TRIM37 and 
results in altered subcellular localization of the mutant TRIM37 protein, 
further suggesting that it is pathogenic.