The phenotypic spectrum in patients with arginine to cysteine mutations in the COL2A1 gene.

BACKGROUND: The majority of COL2A1 missense mutations are substitutions of obligatory glycine residues in the triple helical domain. Only a few non-glycine missense mutations have been reported and among these, the arginine to cysteine substitutions predominate. OBJECTIVE: To investigate in more detail the phenotype resulting from arginine to cysteine mutations in the COL2A1 gene. METHODS: The clinical and radiographic phenotype of all patients in whom an arginine to cysteine mutation in the COL2A1 gene was identified in our laboratory, was studied and correlated with the abnormal genotype. The COL2A1 genotyping involved DHPLC analysis with subsequent sequencing of the abnormal fragments. RESULTS: Six different mutations (R75C, R365C, R519C, R704C, R789C, R1076C) were found in 11 unrelated probands. Each mutation resulted in a rather constant and site-specific phenotype, but a perinatally lethal disorder was never observed. Spondyloarthropathy with normal stature and no ocular involvement were features of patients with the R75C, R519C, or R1076C mutation. Short third and/or fourth toes was a distinguishing feature of the R75C mutation and brachydactyly with enlarged finger joints a key feature of the R1076C substitution. Stickler dysplasia with brachydactyly was observed in patients with the R704C mutation. The R365C and R789C mutations resulted in classic Stickler dysplasia and spondyloepiphyseal dysplasia congenita (SEDC), respectively. CONCLUSIONS: Arginine to cysteine mutations are rather infrequent COL2A1 mutations which cause a spectrum of phenotypes including classic SEDC and Stickler dysplasia, but also some unusual entities that have not yet been recognised and described as type II collagenopathies.

Comparison between the in vitro cytokine production of mononuclear cells of young asthmatics with and without immunotherapy (IT)

BACKGROUND: The underlying mechanisms of immunotherapy (IT) are still unknown but may be related to modifications of cytokine production of T lymphocytes. OBJECTIVE: In this study we determined the in vitro allergen-induced production of IL-2, IL-4, IL-5, IL-12 and IFNgamma of peripheral blood mononuclear cells (PBMC) of eight young asthmatics, aged 15+/-2 years, receiving IT (IT group) and of eight comparable asthmatics, aged 13+/-3.5 years, who never received IT (non-IT group). METHODS: All patients suffered from perennial asthma and were allergic to house dust mite (HDM). They were selected if they showed a positive stimulation index (SI) of PBMC after in vitro incubation with HDM (i.e. SI > 2). Cells were incubated with and without HDM (10 microg/mL) during 24 h, 48 h and 7 days. Cytokines were determined in the supernatant at the three time points and are expressed as median values in pg/mL. RESULTS: In the IT group the secretion of IL-2 was lower compared with the non-IT group after 7 days incubation of PBMC with HDM (0 vs 33.2, P = 0.008). In both groups maximal secretion of IL-2 was observed after 48 h. In the non-IT group a high value of IL-2 persisted after 7 days, whereas in the IT group a significant decline of IL-2 occurred after 7 days. Although IL-4 secretion was low in all subjects, more patients of the non-IT group showed detectable IL-4 in the HDM cultures after 24 h and 48 h, although the difference was not statistically significant (P = 0.08 and P = 0.28, respectively). Furthermore, IL-4 secretion was lower in the HDM cultures after 24 h in the IT group (1.75 vs 4.1, P = 0.011) and 48 h (2.2 vs 4.1, P=0.035). IL-5 secretion was lower in the HDM cultures after 24h (12.4 vs 47.6, P = 0.035) and 48 h (26.8 vs 135, P = 0.046) in the IT group than in the non-IT group. After 7 days of incubation with HDM there was no difference between the groups. There was no difference between both groups in secretion of IFNgamma and IL-12. CONCLUSIONS: These results show a difference in vitro cytokine secretion of PBMC of asthmatics receiving IT compared with asthmatics who never received IT. PBMC of patients receiving IT secrete less IL-2 and IL-5 after in vitro incubation with HDM and show a tendency to secrete less IL-4. The efficacy of IT may be attributed to a modified cytokine secretion of PBMC.