Primary ALS deficiency due to IGFALS mutations should be considered as a possible cause of postnatal growth deficit in IGF-I-deficient patients in the absence of GH deficiency or insensitivity. Determination of serum ALS levels and basal insulinemia can be helpful in the differential diagnosis of patients with idiopathic IGF-I deficiency.

The purpose of this study was to determine whether long-term modulation of inflammatory activity by tumor necrosis factor (TNF)-α inhibitors has some influence on insulin resistance (IR). 16 active rheumatoid arthritis (RA) patients without CV risk factors treated with anti-TNF-α agents were included in this study. RA activity by disease activity score 28, IR by HOMA2-IR, body composition by impedance analysis, physical activity by accelerometry, abdominal fat distribution by magnetic resonance imaging, and serum level of key adipokines by ELISA were measured at baseline and during a 1-year follow-up period. Patient body mass index increased significantly (26.94 ± 3.88 vs. 28.06 ± 4.57 kg/m2, p=0.02) after 1 year of treatment. Body composition, in terms of fat and fat-free mass, remained unchanged except for a significant elevation in body cell mass (25.50 ± 4.60 vs. 26.60 ± 3.17 kg, p=0.02). Basal levels of IR in the RA patients included in this study were significantly higher than healthy controls (1.6 ± 0.8 vs. 1.11 ± 0.56, p=0.011) but did not change during the follow-up. Nor did basal concentrations of adiponectin, visfatin, leptin, ghrelin, resistin, and apelin in response to anti-TNF-α treatment; only retinol-binding protein 4, showed a significant increase (51.7 ± 32.7 vs. 64.9 ± 28.4 μg/ml, p=0.03) at the end of the study. IR, adiposity distribution, and serum levels of most adipokines are not significantly affected by long-term inhibition of TNF-α in RA patients. Our data suggest that although systemic blockade of TNF-α exerts an anticachectic effect in RA patients, it does not seem to play a major role in IR.

BackgroundC-type natriuretic peptide (CNP), its endogenous receptor, natriuretic peptide receptor-B (NPR-B), as well as its downstream mediator, cyclic guanosine monophosphate (cGMP) dependent protein kinase II (cGKII), have been shown to play a pivotal role in chondrogenic differentiation and endochondral bone growth. In humans, biallelic variants in NPR2, encoding NPR-B, cause acromesomelic dysplasia, type Maroteaux, while heterozygous variants in NPR2 (natriuretic peptide receptor 2) and NPPC (natriuretic peptide precursor C), encoding CNP, cause milder phenotypes. In contrast, no variants in cGKII, encoded by the protein kinase cGMP-dependent type II gene (PRKG2), have been reported in humans to date, although its role in longitudinal growth has been clearly demonstrated in several animal models.MethodsExome sequencing was performed in two girls with severe short stature due to acromesomelic limb shortening, brachydactyly, mild to moderate platyspondyly and progressively increasing metaphyseal alterations of the long bones. Functional characterisation was undertaken for the identified variants.ResultsTwo homozygous PRKG2 variants, a nonsense and a frameshift, were identified. The mutant transcripts are exposed to nonsense-mediated decay and the truncated mutant cGKII proteins, partially or completely lacking the kinase domain, alter the downstream mitogen activation protein kinase signalling pathway by failing to phosphorylate c-Raf 1 at Ser43 and subsequently reduce ERK1/2 activation in response to fibroblast growth factor 2. They also downregulate COL10A1 and upregulate COL2A1 expression through SOX9.ConclusionIn conclusion, we have clinically and molecularly characterised a new acromesomelic dysplasia, acromesomelic dysplasia, PRKG2 type (AMDP).