Utilization of extended temporomandibular joint replacements in patients with hemifacial microsomia

Hemifacial microsomia (HFM) patients may benefit from extended temporomandibular joint replacements (eTMJR) to improve function and quality of life. A cross-sectional survey was sent to surgeons who place alloplastic temporomandibular joints regarding their experience with and complications encountered when placing eTMJR in patients with HFM. Fifty-nine responded to the survey. Thirty-six (61.0%) reported treating patients with HFM and 30 (50.8%) of those reported placing an alloplastic temporomandibular joint (TMJ) prosthesis for patients with HFM. Twenty-three of the 30 surgeons (76.7%) placing alloplastic TMJ prostheses reported using an eTMJR in patients with HFM. The average maximum inter-incisal opening (MIO) after an eTMJR in HFM patients was repor ted as> 25 mm by 82.6% of the participants, and between 16 mm and 25 mm by 17.4%. No participants reported MIO < 15 mm. To avoid condylar sag and open bite changes postoperatively, over 70% reported using some form of modification to stabilize the occlusion. Respondents reported good functional outcomes for eTMJR in patients with HFM with relatively few complications. Therefore, eTMJR could be considered a viable option in the management of this patient population.

Pharmacogenetics of oral antidiabetes drugs: evidence for diverse signals at the IRS1 locus

To investigate the role of IRS1 locus on failure to oral antidiabetes drugs (OADs) we genotyped single-nucleotide polymorphisms (SNPs), rs2943641, rs7578326 (tagging all SNPs genome-wide associated with type 2 diabetes (T2D) and related traits at this locus) and rs1801278 (that is, the loss-of-function IRS1 G972R amino acid substitution) in 2662 patients with T2D. Although no association with OAD failure was observed for rs2943641 and rs7578326 SNPs (odds ratio (OR): 1.04, 95% confidence interval (CI): 0.93-1.16 and OR: 0.97, 95% CI: 0.87-1.09 respectively), a significant association was observed for rs1801278 (OR: 1.34, 95% CI: 1.08-1.66). When meta-analyzed with previous published data, an allelic OR of 1.41 (1.15-1.72; P=0.001) was obtained, so that homozygous R972R individuals have >80% higher risk of failing to OADs as compared with their G972G counterparts. In all, though further studies are needed for confirming this finding, our present data point to IRS1 rs1801278 as a potential biomarker for pursuing the goal of stratified medicine in the field of antihyperglycemic treatment in T2D.

The SH2B1 obesity locus and abnormal glucose homeostasis: lack of evidence for association from a meta-analysis in individuals of European ancestry

BACKGROUND/AIMS

The development of type 2 diabetes (T2D) is influenced both by environmental and by genetic determinants. Obesity is an important risk factor for T2D, mostly mediated by obesity-related insulin resistance. Obesity and insulin resistance are also modulated by the genetic milieu; thus, genes affecting risk of obesity and insulin resistance might also modulate risk of T2D. Recently, 32 loci have been associated with body mass index (BMI) by genome-wide studies, including one locus on chromosome 16p11 containing the SH2B1 gene. Animal studies have suggested that SH2B1 is a physiological enhancer of the insulin receptor and humans with rare deletions or mutations at SH2B1 are obese with a disproportionately high insulin resistance. Thus, the role of SH2B1 in both obesity and insulin resistance makes it a strong candidate for T2D. However, published data on the role of SH2B1 variability on the risk for T2D are conflicting, ranging from no effect at all to a robust association.

METHODS

The SH2B1 tag SNP rs4788102 (SNP, single nucleotide polymorphism) was genotyped in 6978 individuals from six studies for abnormal glucose homeostasis (AGH), including impaired fasting glucose, impaired glucose tolerance or T2D, from the GENetics of Type 2 Diabetes in Italy and the United States (GENIUS T2D) consortium. Data from these studies were then meta-analyzed, in a Bayesian fashion, with those from DIAGRAM+ (n = 47,117) and four other published studies (n = 39,448).

RESULTS

Variability at the SH2B1 obesity locus was not associated with AGH either in the GENIUS consortium (overall odds ratio (OR) = 0.96; 0.89-1.04) or in the meta-analysis (OR = 1.01; 0.98-1.05).

CONCLUSION

Our data exclude a role for the SH2B1 obesity locus in the modulation of AGH.

Two new severe mutations causing guanidinoacetate methyltransferase deficiency

Primary disorders of creatine metabolism have been only recently described. We report new molecular and biochemical findings obtained from a child affected by guanidinoacetate methyltransferase deficiency. This patient presented with neurological regression, epilepsy, and a movement disorder during the first year of life. HPLC analysis showed high concentrations of guanidinoacetic acid in urine, plasma, and CSF. Molecular analyses of cDNA and genomic DNA revealed two novel mutations, a G insertion following nucleotide 491 of the cDNA (c.491insG) in exon 5 and a transversion at nt -3 in intron 5 (IVS5-3C>G). The c.491insG mutation causes a frameshift and a premature stop codon at the end of the exon. The IVS5-3C>G mutation prevents the splicing of the last exon of the gene precluding the complete maturation of the transcript and, most likely, causes rapid degradation of the mRNA.