X Chromosome Dose and Sex Bias in Autoimmune Diseases: Increased Prevalence of 47,XXX in Systemic Lupus Erythematosus and Sjögren's Syndrome

OBJECTIVE

More than 80% of autoimmune disease predominantly affects females, but the mechanism for this female bias is poorly understood. We suspected that an X chromosome dose effect accounts for this, and we undertook this study to test our hypothesis that trisomy X (47,XXX; occurring in ∼1 in 1,000 live female births) would be increased in patients with female-predominant diseases (systemic lupus erythematosus [SLE], primary Sjögren's syndrome [SS], primary biliary cirrhosis, and rheumatoid arthritis [RA]) compared to patients with diseases without female predominance (sarcoidosis) and compared to controls.

METHODS

All subjects in this study were female. We identified subjects with 47,XXX using aggregate data from single-nucleotide polymorphism arrays, and, when possible, we confirmed the presence of 47,XXX using fluorescence in situ hybridization or quantitative polymerase chain reaction.

RESULTS

We found 47,XXX in 7 of 2,826 SLE patients and in 3 of 1,033 SS patients, but in only 2 of 7,074 controls (odds ratio in the SLE and primary SS groups 8.78 [95% confidence interval 1.67-86.79], P = 0.003 and odds ratio 10.29 [95% confidence interval 1.18-123.47], P = 0.02, respectively). One in 404 women with SLE and 1 in 344 women with SS had 47,XXX. There was an excess of 47,XXX among SLE and SS patients.

CONCLUSION

The estimated prevalence of SLE and SS in women with 47,XXX was ∼2.5 and ∼2.9 times higher, respectively, than that in women with 46,XX and ∼25 and ∼41 times higher, respectively, than that in men with 46,XY. No statistically significant increase of 47,XXX was observed in other female-biased diseases (primary biliary cirrhosis or RA), supporting the idea of multiple pathways to sex bias in autoimmunity.

The IRF5-TNPO3 association with systemic lupus erythematosus has two components that other autoimmune disorders variably share

Exploiting genotyping, DNA sequencing, imputation and trans-ancestral mapping, we used Bayesian and frequentist approaches to model the IRF5-TNPO3 locus association, now implicated in two immunotherapies and seven autoimmune diseases. Specifically, in systemic lupus erythematosus (SLE), we resolved separate associations in the IRF5 promoter (all ancestries) and with an extended European haplotype. We captured 3230 IRF5-TNPO3 high-quality, common variants across 5 ethnicities in 8395 SLE cases and 7367 controls. The genetic effect from the IRF5 promoter can be explained by any one of four variants in 5.7 kb (P-valuemeta = 6 × 10(-49); OR = 1.38-1.97). The second genetic effect spanned an 85.5-kb, 24-variant haplotype that included the genes IRF5 and TNPO3 (P-valuesEU = 10(-27)-10(-32), OR = 1.7-1.81). Many variants at the IRF5 locus with previously assigned biological function are not members of either final credible set of potential causal variants identified herein. In addition to the known biologically functional variants, we demonstrated that the risk allele of rs4728142, a variant in the promoter among the lowest frequentist probability and highest Bayesian posterior probability, was correlated with IRF5 expression and differentially binds the transcription factor ZBTB3. Our analytical strategy provides a novel framework for future studies aimed at dissecting etiological genetic effects. Finally, both SLE elements of the statistical model appear to operate in Sjögren's syndrome and systemic sclerosis whereas only the IRF5-TNPO3 gene-spanning haplotype is associated with primary biliary cirrhosis, demonstrating the nuance of similarity and difference in autoimmune disease risk mechanisms at IRF5-TNPO3.

Variants at multiple loci implicated in both innate and adaptive immune responses are associated with Sjögren's syndrome

Sjögren’s syndrome is a common autoimmune disease (~0.7% of European Americans) typically presenting as keratoconjunctivitis sicca and xerostomia. In addition to strong association within the HLA region at 6p21 (P_meta=7.65×10⁻¹¹⁴), we establish associations with IRF5-TNPO3 (P_meta=2.73×10⁻¹⁹), STAT4 (P_meta=6.80×10⁻¹⁵), IL12A (P_meta =1.17×10⁻¹⁰), FAM167A-BLK (P_meta=4.97×10⁻¹⁰), DDX6-CXCR5 (P_meta=1.10×10⁻⁸), and TNIP1 (P_meta=3.30×10⁻⁸). Suggestive associations with P_meta<5×10⁻⁵ were observed with 29 regions including TNFAIP3, PTTG1, PRDM1, DGKQ, FCGR2A, IRAK1BP1, ITSN2, and PHIP amongst others. These results highlight the importance of genes involved in both innate and adaptive immunity in Sjögren’s syndrome.

Telehealth in a rural school-based health center

Telehealth is a new technology for the delivery of health care that allows a provider to deliver health care to a client at a remote setting via full, real-time video and audio interaction (American Nurses' Association, 1996). Telehealth does not change traditional health care standards or practice. School-based health centers are designed specifically for children and offer a continuum of preventive and acute care interventions that few other health care entities can provide (School-Based Adolescent Health Care Program, 1993). Telehealth and a school-based health center were joined together in a pilot project to demonstrate the efficacy of primary care via telehealth and to determine the value of this technology to the school and community. The telehealth capability enhanced the role of the school nurse and increased access to primary care for the students. The students were quick to adapt to the technology. The role of the school nurse was essential to the success of this project.

Isolated atlantoaxial rotatory fixation in a child with seronegative spondyloarthropathy presenting with torticollis

Children presenting with torticollis demand thorough investigation. Atlantoaxial subluxation and rotatory fixation should be included in the differential diagnosis even in the absence of neurologic findings. We describe a 9-year-old boy with this condition associated with HLA-B27 positive seronegative spondyloarthropathy that went undiagnosed for 11 weeks. No other radiographic changes were seen, including no erosions. No neurologic findings were present. The child was treated with Halter head traction, which successfully reduced the atlantoaxial joint. This was followed by posterior C1-C2 fusion secondary to instability. Rheumatologists should be aware of this condition when examining a child presenting with torticollis.

Prazosin treatment of Raynaud's phenomenon: a double blind single crossover study

The efficacy of prazosin (Minipress) for the treatment of Raynaud's phenomenon (RP) was assessed by patient diary data and by objective measurements of digital vessel patency before and after cold challenge. Nine of the 14 patients with complete data reported fewer RP episodes during the 2 weeks in which they received prazosin than with placebo. Eight of 9 patients in Group 1 (systemic lupus erythematosus, mixed connective tissue disease or idiopathic RP) reported improvement during prazosin therapy (p less than 0.05) while only one of 5 patients with progressive systemic sclerosis (PSS, Group 2) reported benefit. Objective measurements indicated a significant decrease (p less than 0.02) in digital artery resistance with prazosin only in Group 1. These data predict that prazosin may be beneficial in the treatment of RP for patients who do not also have PSS.