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DNAJC12, a type III member of the HSP40/DNAJ family, has been identified as the specific co‐chaperone of phenylalanine hydroxylase (PAH) and the other aromatic amino acid hydroxylases. DNAJ proteins work together with molecular chaperones of the HSP70 family to assist in proper folding and maintenance of intracellular stability of their clients. Autosomal recessive mutations in DNAJC12 were found to reduce PAH levels, leading to hyperphenylalaninemia (HPA) in patients without mutations in PAH. In this work, we investigated the interaction of normal wild‐type DNAJC12 with mutant PAH in cells expressing several PAH variants associated with HPA in humans, as well as in the Enu1/1 mouse model, homozygous for the V106A‐Pah variant, which leads to severe protein instability, accelerated PAH degradation and mild HPA. We found that mutant PAH exhibits increased ubiquitination, instability, and aggregation compared with normal PAH. In mouse liver lysates, we showed that DNAJC12 interacts with monoubiquitin‐tagged PAH. This form represented a major fraction of PAH in the Enu1/1 but was also present in liver of wild‐type PAH mice. Our results support a role of DNAJC12 in the processing of misfolded ubiquitinated PAH by the ubiquitin‐dependent proteasome/autophagy systems and add to the evidence that the DNAJ proteins are important players both for proper folding and degradation of their clients. DNAJC12 has been identified as the specific co‐chaperone of phenylalanine hydroxylase (PAH) and mutations in DNAJC12 have been associated with hyperphenylalaninemia (HPA). In this work we demonstrate a strong reduction of PAH‐like immunoreactivity and an increased ubiquitination of mutant PAH in the liver of HPA Enu1/1 mice compared with wild‐type (Wt) mice. Our results also reveal the interaction of DNAJC12 with mono‐ubiquitin‐tagged PAH, supporting a role of DNAJC12 in the processing of misfolded PAH. [ABSTRACT FROM AUTHOR]

Key Clinical Message Primary cutaneous plasmacytoma should be in the differential diagnosis in case of solitary or multiple erythematous-violaceous nodules or papules. The diagnosis relies on clinical, histological, and immunochemical findings, without underlying evidence of multiple myeloma. Treatment should be individualized, and agents such as bortezomib or lenalidomide have shown to be effective. [ABSTRACT FROM AUTHOR]

Methylmalonic aciduria ( MMA) cblB type is caused by mutations in the MMAB gene, which codes for the enzyme adenosine triphosphate ( ATP): cobalamin adenosyltransferase ( ATR). This study reports differences in the metabolic and disease outcomes of two pairs of siblings with MMA cblB type, respectively harbouring the novel changes p. His183Leu/p.Arg190dup ( P1 and P2) and the previously described mutations p. Ile96Thr/p.Ser174fs ( P3 and P4). Expression analysis showed p. His183Leu and p.Arg190dup to be destabilizing mutations. Both were associated with reduced ATR stability and a shorter half-life than wild-type ATR. Analysis of several parameters related to oxidative stress and mitochondrial function showed an increase in reactive oxygen species ( ROS) content, a decrease in mitochondrial respiration and changes in mitochondria morphology and structure in patient-derived fibroblasts compared to control cells. The impairment in energy production and the presence of oxidative stress and fission of the mitochondrial reticulum suggested mitochondrial dysfunction in cblB patients' fibroblasts. The recovery of mitochondrial function should be a goal in efforts to improve the clinical outcome of MMA cblB type. [ABSTRACT FROM AUTHOR]

ATP:cob(I)alamin adenosyltransferase (ATR, E.C.2.5.1.17) converts reduced cob(I)alamin to the adenosylcobalamin cofactor. Mutations in the MMAB gene encoding ATR are responsible for the cblB type methylmalonic aciduria. Here we report the functional analysis of five cblB mutations to determine the underlying molecular basis of the dysfunction. The transcriptional profile along with minigenes analysis revealed that c.584G>A, c.349-1G>C, and c.290G>A affect the splicing process. Wild-type ATR and the p.I96T (c.287T>C) and p.R191W (c.571C>T) mutant proteins were expressed in a prokaryote and a eukaryotic expression systems. The p.I96T protein was enzymatically active with a K M for ATP and K D for cob(I)alamin similar to wild-type enzyme, but exhibited a 40% reduction in specific activity. Both p.I96T and p.R191W mutant proteins are less stable than the wild-type protein, with increased stability when expressed under permissive folding conditions. Analysis of the oligomeric state of both mutants showed a structural defect for p.I96T and also a significant impact on the amount of recovered mutant protein that was more pronounced for p.R191W that, along with the structural analysis, suggest they might be misfolded. These results could serve as a basis for the implementation of pharmacological therapies aimed at increasing the residual activity of this type of mutations. Hum Mutat 31:1033-1042, 2010. © 2010 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Development of pseudoexon exclusion therapies by antisense modification of pre-mRNA splicing represents a type of personalized genetic medicine. Here we present the cellular antisense therapy and the cell-based splicing assays to investigate the effect of two novel deep intronic changes c.1957-898A>G and c.1957-920C>A identified in the methylmalonyl-coenzyme A (CoA) mutase (MUT) gene. The results show that the nucleotide change c.1957-898A>G is a pathological mutation activating pseudoexon insertion and that antisense morpholino oligonucleotide (AMO) treatment in patient fibroblasts leads to recovery of MUT activity to levels 25 to 100% of control range. On the contrary, the change c.1957-920C>A, identified in two fibroblasts cell lines in cis with c.1885A>G (p.R629G) or c.458T>A (p.D153V), appears to be a rare variant of uncertain clinical significance. The functional analysis of c.1885A>G and c.458T>A indicate that they are the disease-causing mutations in these two patients. The results presented here highlight the necessity of scanning the described intronic region for mutations in MUT-affected patients, followed by functional analyses to demonstrate the pathogenicity of the identified changes, and extend previous work of the applicability of the antisense approach in methylmalonic aciduria (MMAuria) for a novel intronic mutation. Hum Mutat 30:1-7, 2009. © 2009 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Methylmalonic aciduria (MMA) cobalamin deficiency type C ( cblC) with homocystinuria (MMACHC) is the most frequent genetic disorder of vitamin B12 metabolism. The aim of this work was to identify the mutational spectrum in a cohort of cblC-affected patients and the analysis of the cellular oxidative stress and apoptosis processes, in the presence or absence of vitamin B12. The mutational spectrum includes nine previously described mutations: c.3G>A (p.M1L), c.217C>T (p.R73X), c.271dupA (p.R91KfsX14), c.331C>T (p.R111X), c.394C>T (p.R132X), c.457C>T (p.R153X), c.481C>T (p.R161X), c.565C>A (p.R189S), and c.615C>G (p.Y205X), and two novel changes, c.90G>A (p.W30X) and c.81+2T>G (IVS1+2T>G). The most frequent change was the known c.271dupA mutation, which accounts for 85% of the mutant alleles characterized in this cohort of patients. Owing to its high frequency, a real-time PCR and subsequent high-resolution melting (HRM) analysis for this mutation has been established for diagnostic purposes. All cell lines studied presented a significant increase of intracellular reactive oxygen species (ROS) content, and also a high rate of apoptosis, suggesting that elevated ROS levels might induce apoptosis in cblC patients. In addition, ROS levels decreased in hydroxocobalamin-incubated cells, indicating that cobalamin might either directly or indirectly act as a scavenger of ROS. ROS production might be considered as a phenotypic modifier in cblC patients, and cobalamin supplementation or additional antioxidant drugs might suppress apoptosis and prevent cellular damage in these patients. Hum Mutat 30:1-9, 2009. © 2009 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

On the Back Cover: This cover image is based on the Research Article Phenylalanine hydroxylase variants interact with the co‐chaperone DNAJC12 by Kunwar Jung‐KC et al., Pages 483–494. DOI: 10.1002/humu.23712. [ABSTRACT FROM AUTHOR]

Photographs showing the pediatric dermatology condition of a congenital erythematous plaques and papules on the right arm of a 3-year old girl are presented.