American College of Rheumatology Guidance for the Management of Pediatric Rheumatic Disease During the COVID-19 Pandemic: Version 2.

OBJECTIVE: To provide clinical guidance to rheumatology providers who treat children with pediatric rheumatic disease (PRD) in the context of the coronavirus disease 2019 (COVID-19) pandemic. METHODS: The task force, consisting of 7 pediatric rheumatologists, 2 pediatric infectious disease physicians, 1 adult rheumatologist, and 1 pediatric nurse practitioner, was convened on May 21, 2020. Clinical questions and subsequent guidance statements were drafted based on a review of the queries posed by the patients as well as the families and healthcare providers of children with PRD. An evidence report was generated and disseminated to task force members to assist with 3 rounds of asynchronous, anonymous voting by email using a modified Delphi approach. Voting was completed using a 9-point numeric scoring system with predefined levels of agreement (categorized as disagreement, uncertainty, or agreement, with median scores of 1-3, 4-6, and 7-9, respectively) and consensus (categorized as low, moderate, or high). To be approved as a guidance statement, median vote ratings were required to fall into the highest tertile for agreement, with either moderate or high levels of consensus. RESULTS: To date, 39 guidance statements have been approved by the task force. Those with similar recommendations were combined to form a total of 33 final guidance statements, all of which received median vote ratings within the highest tertile of agreement and were associated with either moderate consensus (n = 5) or high consensus (n = 28). CONCLUSION: These guidance statements have been generated based on review of the available literature, indicating that children with PRD do not appear to be at increased risk for susceptibility to SARS-CoV-2 infection. This guidance is presented as a "living document," recognizing that the literature on COVID-19 is rapidly evolving, with future updates anticipated.

American College of Rheumatology Guidance for the Management of Pediatric Rheumatic Disease During the COVID-19 Pandemic: Version 1.

OBJECTIVE: To provide clinical guidance to rheumatology providers who treat children with pediatric rheumatic disease (PRD) in the context of the coronavirus disease 2019 (COVID-19) pandemic. METHODS: The task force, consisting of 7 pediatric rheumatologists, 2 pediatric infectious disease physicians, 1 adult rheumatologist, and 1 pediatric nurse practitioner, was convened on May 21, 2020. Clinical questions and subsequent guidance statements were drafted based on a review of the queries posed by the patients as well as the families and healthcare providers of children with PRD. An evidence report was generated and disseminated to task force members to assist with 3 rounds of asynchronous, anonymous voting by email using a modified Delphi approach. Voting was completed using a 9-point numeric scoring system with predefined levels of agreement (categorized as disagreement, uncertainty, or agreement, with median scores of 1-3, 4-6, and 7-9, respectively) and consensus (categorized as low, moderate, or high). To be approved as a guidance statement, median vote ratings were required to fall into the highest tertile for agreement, with either moderate or high levels of consensus. RESULTS: The task force drafted 33 guidance statements, which were voted upon during the second and third rounds of voting. Of these 33 statements, all received median vote ratings within the highest tertile of agreement and were associated with either moderate consensus (n = 6) or high consensus (n = 27). Statements with similar recommendations were combined, resulting in 27 final guidance statements. CONCLUSION: These guidance statements have been generated based on review of the available literature, indicating that children with PRD do not appear to be at increased risk for susceptibility to SARS-CoV-2 infection. This guidance is presented as a "living document," recognizing that the literature on COVID-19 is rapidly evolving, with future updates anticipated.

Healthcare Use Patterns and Economic Burden of Chronic Musculoskeletal Pain in Children before Diagnosis.

OBJECTIVES: To evaluate the healthcare use and costs of amplified musculoskeletal pain syndrome (AMPS) in children before diagnosis. STUDY DESIGN: We performed a retrospective study in children with AMPS at a pediatric rheumatology clinic between 2010 and 2014. Data were abstracted on 80 patients after primary rheumatic diseases were excluded. Healthcare visits, medications and diagnostic testing that occurred in the years before diagnosis were collected. The Medical Expenditure Panel Survey was used to estimate visit costs. RESULTS: Patients were adolescent females (89%) and white (86%). The median time to diagnosis was 10.2 months. The median pain score was 6.5 and the median Childhood Health Assessment Questionnaire score was 1.1. In this cohort, 29% had at least 1 ED visit and 5% were hospitalized. All patients saw a rheumatologist and 41% had visited another specialist, typically orthopedics and sports medicine. More than one-half had at least 1 radiographic study and 21% had at least 1 magnetic resonance imaging. The total cost for office, emergency department, and hospital visits for AMPS in all 80 patients was $152 853. The mean cost per patient over the entire study period (2008-2014) was $1911 ± $3808, and 43% of costs were outpatient visits. CONCLUSIONS: Children with AMPS have high levels of disability and take a long time to be diagnosed. As a result, even before diagnosis, they have high levels of healthcare use, diagnostic testing, and medical costs. Early recognition of disability and quicker referral to trained subspecialists may improve the prognosis, reduce unnecessary testing, and reduce the overall costs of healthcare.

Barriers to Adherence in Juvenile Idiopathic Arthritis: A Multicenter Collaborative Experience and Preliminary Results.

OBJECTIVE: Nonadherence is currently an underrecognized and potentially modifiable obstacle to care in juvenile idiopathic arthritis (JIA). The purpose of our study was to design and implement a standardized approach to identifying adherence barriers for youth with JIA across 7 pediatric rheumatology clinics through the Pediatric Rheumatology Care and Outcomes Improvement Network (PR-COIN) and to assess the frequency of adherence barriers in patients and their caregivers across treatment modalities. METHODS: An iterative process using coproduction among parents and providers of patients with JIA was used to design the Barriers Assessment Tool to screen for adherence barriers across 4 treatment modalities (i.e., oral medications, injectable medications, infusions, and physical/occupational therapy). This tool was implemented in 7 rheumatology clinics across the United States and patient responses were collected for analysis. RESULTS: Data were collected from 578 parents and 99 patients (n = 44 parent-child dyads). Seventy-seven percent (n = 444) of caregivers and 70% (n = 69) of patients reported at least 1 adherence barrier across all treatment components. The most commonly reported adherence barriers included worry about future consequences of therapy, pain, forgetting, side effects, and embarrassment related to the therapy. There was no significant difference between endorsement of barriers between parents and adolescents. CONCLUSION: Implementing a standardized tool assessing adherence barriers in the JIA population across multiple clinical settings is feasible. Systematic screening sheds light on the factors that make adherence difficult in JIA and identifies targets for future adherence interventions in clinical practice.

2015 American College of Rheumatology Workforce Study: Supply and Demand Projections of Adult Rheumatology Workforce, 2015-2030.

OBJECTIVE: To describe the character and composition of the 2015 US adult rheumatology workforce, evaluate workforce trends, and project supply and demand for clinical rheumatology care for 2015-2030. METHODS: The 2015 Workforce Study of Rheumatology Specialists in the US used primary and secondary data sources to estimate the baseline adult rheumatology workforce and determine demographic and geographic factors relevant to workforce modeling. Supply and demand was projected through 2030, utilizing data-driven estimations regarding the proportion and clinical full-time equivalent (FTE) of academic versus nonacademic practitioners. RESULTS: The 2015 adult workforce (physicians, nurse practitioners, and physician assistants) was estimated to be 6,013 providers (5,415 clinical FTE). At baseline, the estimated demand exceeded the supply of clinical FTE by 700 (12.9%). By 2030, the supply of rheumatology clinical providers is projected to fall to 4,882 providers, or 4,051 clinical FTE (a 25.2% decrease in supply from 2015 baseline levels). Demand in 2030 is projected to exceed supply by 4,133 clinical FTE (102%). CONCLUSION: The adult rheumatology workforce projections reflect a major demographic and geographic shift that will significantly impact the supply of the future workforce by 2030. These shifts include baby-boomer retirements, a millennial predominance, and an increase of female and part-time providers, in parallel with an increased demand for adult rheumatology care due to the growing and aging US population. Regional and innovative strategies will be necessary to manage access to care and reduce barriers to care for rheumatology patients.

Design and implementation of a decision aid for juvenile idiopathic arthritis medication choices.

BACKGROUND: Randomized trials have demonstrated the efficacy of patient decision aids to facilitate shared decision making in clinical situations with multiple medically reasonable options for treatment. However, little is known about how best to implement these tools into routine clinical practice. In addition, reliable implementation of decision aids has been elusive and spread within pediatrics has been slow. We sought to develop and reliably implement a decision aid for treatment of children with juvenile idiopathic arthritis. METHODS: To design our decision aid, we partnered with patient, parent, and clinician stakeholders from the Pediatric Rheumatology Care and Outcomes Improvement Network. Six sites volunteered to use quality improvement methods to implement the decision aid. Four of these sites collected parent surveys following visits to assess outcomes. Parents reported on clinician use of the decision aid and the amount of shared decision making and uncertainty they experienced. We used chi-square tests to compare eligible visits with and without use of the decision aid on the experience of shared decision making and uncertainty. RESULTS: After 18 rounds of testing and revision, stakeholders approved the decision aid design for regular use. Qualitative feedback from end-users was positive. During the implementation project, the decision aid was used in 35% of visits where starting or switching medication was discussed. Clinicians used the decision aid as intended in 68% of these visits. The vast majority of parents reported high levels of shared decision making following visits with (64/76 = 84%) and without (80/95 = 84%) use of the decision aid (p = 1). Similarly, the vast majority of parents reported no uncertainty following visits with (74/76 = 97%) and without (91/95 = 96%) use of the decision aid (p = 0.58). CONCLUSIONS: Although user acceptability of the decision aid was high, reliable implementation in routine clinical care proved challenging. Our parsimonious approach to outcome assessment failed to detect a difference between visits with and without use of our aid. Innovative approaches are needed to facilitate use of decision aids and the assessment of outcomes.

Effects of Complement C4 Gene Copy Number Variations, Size Dichotomy, and C4A Deficiency on Genetic Risk and Clinical Presentation of Systemic Lupus Erythematosus in East Asian Populations.

OBJECTIVE: Human complement C4 is complex, with multiple layers of diversity. The aims of this study were to elucidate the copy number variations (CNVs) of C4A and C4B in relation to disease risk in systemic lupus erythematosus (SLE), and to compare the basis of race-specific C4A deficiency between East Asians and individuals of European descent. METHODS: The East Asian study population included 999 SLE patients and 1,347 healthy subjects. Variations in gene copy numbers (GCNs) of total C4, C4A, and C4B, as well as C4-Long and C4-Short genes, were determined and validated using independent genotyping technologies. Genomic regions with C4B96 were investigated to determine the basis of the most basic C4B protein occurring concurrently with C4A deficiency. RESULTS: In East Asians, high GCNs of total C4 and C4A were strongly protective against SLE, whereas low and medium GCNs of total C4 and C4A, and the absence of C4-Short genes, were risk factors for SLE. Homozygous C4A deficiency was infrequent in East Asian subjects, but had an odds ratio (OR) of 12.4 (P = 0.0015) for SLE disease susceptibility. Low serum complement levels were strongly associated with low GCNs of total C4 (OR 3.19, P = 7.3 × 10(-7) ) and C4B (OR 2.53, P = 2.5 × 10(-5) ). Patients with low serum complement levels had high frequencies of anti-double-stranded DNA antibodies (OR 4.96, P = 9.7 × 10(-17) ), hemolytic anemia (OR 3.89, P = 3.6 × 10(-10) ), and renal disease (OR 2.18, P = 8.5 × 10(-6) ). The monomodular-Short haplotype found to be prevalent in European Americans with C4A deficiency, which was in linkage disequilibrium with HLA-DRB1*0301, was scarce in East Asians. Instead, most East Asian subjects with C4A deficiency were found to have a recombinant haplotype with bimodular C4-Long and C4-Short genes, encoding C4B1 and C4B96, which was linked to HLA-DRB1*1501. DNA sequencing revealed an E920K polymorphism in C4B96. CONCLUSION: C4 CNVs and deficiency of C4A both play an important role in the risk and manifestations of SLE in East Asian and European populations.

Gene copy-number variations (CNVs) of complement C4 and C4A deficiency in genetic risk and pathogenesis of juvenile dermatomyositis.

OBJECTIVE: Complement-mediated vasculopathy of muscle and skin are clinical features of juvenile dermatomyositis (JDM). We assess gene copy-number variations (CNVs) for complement C4 and its isotypes, C4A and C4B, in genetic risks and pathogenesis of JDM. METHODS: The study population included 105 patients with JDM and 500 healthy European Americans. Gene copy-numbers (GCNs) for total C4, C4A, C4B and HLA-DRB1 genotypes were determined by Southern blots and qPCRs. Processed activation product C4d bound to erythrocytes (E-C4d) was measured by flow cytometry. Global gene-expression microarrays were performed in 19 patients with JDM and seven controls using PAXgene-blood RNA. Differential expression levels for selected genes were validated by qPCR. RESULTS: Significantly lower GCNs and differences in distribution of GCN groups for total C4 and C4A were observed in JDM versus controls. Lower GCN of C4A in JDM remained among HLA DR3-positive subjects (p=0.015). Homozygous or heterozygous C4A-deficiency was present in 40.0% of patients with JDM compared with 18.2% of controls (OR=3.00 (1.87 to 4.79), p=8.2×10(-6)). Patients with JDM had higher levels of E-C4d than controls (p=0.004). In JDM, C4A-deficient subjects had higher levels of E-C4d (p=0.0003) and higher frequency of elevated levels of multiple serum muscle enzymes at diagnosis (p=0.0025). Microarray profiling of blood RNA revealed upregulation of type I interferon-stimulated genes and lower abundance of transcripts for T-cell and chemokine function genes in JDM, but this was less prominent among C4A-deficient or DR3-positive patients. CONCLUSIONS: Complement C4A deficiency appears to be an important factor for the genetic risk and pathogenesis of JDM, particularly in patients with a DR3-positive background.

Quantitative evaluation of a pediatric rheumatology transition program.

BACKGROUND: Transition from pediatric to adult care can be a challenging process which leaves young people vulnerable to interruptions of care and worsening disease status. Efforts to improve transition processes and outcomes have included development of individualized transition plans, creation of transition clinics, and utilization of transition coordinators. Few interventions have assessed transition outcomes quantitatively. METHODS: We assessed transition outcome and satisfaction of a social worker-centered transition program in a pediatric rheumatology clinic. The social worker met with patients who were 16 years or older and their families, provided transition education materials, assisted patients in developing an individualized transition plan, assisted in making appointments with an adult rheumatologist at time of transfer of care, and followed up with patients to assess transition outcomes. Patients were contacted 6-8 months after initial appointment with the adult rheumatologist to assess whether they remained in the care of the adult provider. Participants then completed a questionnaire to rate their satisfaction with the transition program. RESULTS: 210 adolescents and young adults participated in the transition program. Twenty-six similarly aged patients were eligible for transition services but did not participate in the program and were used as controls. Of the patients who participated in the program, 42% were considered to have transitioned successfully to adult care compared to 23% of controls (p-value = 0.002) of all patients. In the survey of satisfaction, 81% of participants said that they were satisfied with the transition process. CONCLUSIONS: This study shows that a social worker transition coordinator can significantly improve the rate of pediatric rheumatology patients who successfully transition to adult care. Furthermore, patients are largely satisfied with this process.

Choosing Wisely: the American College of Rheumatology's Top 5 for pediatric rheumatology.

OBJECTIVE: To create a pediatric rheumatology Top 5 list as part of the American Board of Internal Medicine Foundation's Choosing Wisely campaign. METHODS: Delphi surveys of a core group of representative pediatric rheumatology providers from across North America generated candidate Top 5 items. Items with high content agreement and perceived to be of prevalent use and of high impact were included in a survey of all American College of Rheumatology (ACR) members who identified themselves as providing care to pediatric patients. Items with the highest ratings were subjected to literature review and further evaluation. RESULTS: A total of 121 candidate items were proposed in the initial Delphi survey and were reduced to 28 items in subsequent surveys. These 28 items were sent to 1,198 rheumatology providers who care for pediatric patients, and 397 (33%) responded. Based upon survey data and literature review, the Top 5 items were identified. These items focused on testing for antinuclear antibodies, autoantibody panels, Lyme disease, methotrexate toxicity monitoring, and use of routine radiographs. CONCLUSION: The ACR pediatric rheumatology Top 5 is one of the first pediatric subspecialty-specific Choosing Wisely Top 5 lists and provides an opportunity for patients and providers to discuss appropriate use of health care in pediatric rheumatology.

Ultrasound-guided corticosteroid injection therapy for juvenile idiopathic arthritis: 12-year care experience.

BACKGROUND: Intra-articular corticosteroid injections are a safe and effective treatment for patients with juvenile idiopathic arthritis. The potential scope of care in ultrasound-guided corticosteroid therapy in children and a joint-based corticosteroid dose protocol designed to optimize interdisciplinary care are not found in the current literature. OBJECTIVE: The purpose of this study was to report the spectrum of care, technique and safety of ultrasound-guided corticosteroid injection therapy in patients with juvenile idiopathic arthritis and to propose an age-weight-joint-based corticosteroid dose protocol. MATERIALS AND METHODS: A retrospective analysis was performed of 198 patients (ages 21 months to 28 years) referred for treatment of juvenile idiopathic arthritis with corticosteroid therapy. Symptomatic joints and tendon sheaths were treated as prescribed by the referring rheumatologist. An age-weight-joint-based dose protocol was developed and utilized for corticosteroid dose prescription. RESULTS: A total of 1,444 corticosteroid injections (1,340 joints, 104 tendon sheaths) were performed under US guidance. Injection sites included small, medium and large appendicular skeletal joints (upper extremity 497, lower extremity 837) and six temporomandibular joints. For patients with recurrent symptoms, 414 repeat injections were performed, with an average time interval of 17.7 months (range, 0.5-101.5 months) between injections. Complications occurred in 2.6% of injections and included subcutaneous tissue atrophy, skin hypopigmentation, erythema and pruritis. CONCLUSION: US-guided corticosteroid injection therapy provides dynamic, precise and safe treatment of a broad spectrum of joints and tendon sheaths throughout the entire pediatric musculoskeletal system. An age-weight-joint-based corticosteroid dose protocol is effective and integral to interdisciplinary care of patients with juvenile idiopathic arthritis.

Anakinra as first-line disease-modifying therapy in systemic juvenile idiopathic arthritis: report of forty-six patients from an international multicenter series.

OBJECTIVE: To examine the safety and efficacy of the interleukin-1 (IL-1) receptor antagonist anakinra as first-line therapy for systemic juvenile idiopathic arthritis (JIA). METHODS: Patients with systemic JIA receiving anakinra as part of initial disease-modifying antirheumatic drug (DMARD) therapy were identified from 11 centers in 4 countries. Medical records were abstracted using a standardized instrument, and resulting data were analyzed to characterize concomitant therapies, clinical course, adverse events, and predictors of outcome. RESULTS: Among 46 patients meeting inclusion criteria, anakinra monotherapy was used in 10 patients (22%), while 67% received corticosteroids and 33% received additional DMARDs. Outcomes were evaluated at a median followup interval of 14.5 months. Fever and rash resolved within 1 month in >95% of patients, while C-reactive protein and ferritin normalized within this interval in >80% of patients. Active arthritis persisted at 1 month in 39% of patients, at 3 months in 27%, and at >6 months of followup in 11%. Approximately 60% of patients, including 8 of 10 receiving anakinra monotherapy, attained a complete response without escalation of therapy. Disease characteristics and treatment were similar in partial and complete responders, except that partial responders were markedly younger at onset (median age 5.2 years versus 10.2 years; P = 0.004). Associated adverse events included documented bacterial infection in 2 patients and hepatitis in 1 patient. Tachyphylaxis was not observed. CONCLUSION: Anakinra as first-line therapy for systemic JIA was associated with rapid resolution of systemic symptoms and prevention of refractory arthritis in almost 90% of patients during the interval examined. These results justify further study of IL-1 inhibition as first-line, rather than rescue, therapy in systemic JIA.

Gene copy-number variation and associated polymorphisms of complement component C4 in human systemic lupus erythematosus (SLE): low copy number is a risk factor for and high copy number is a protective factor against SLE susceptibility in European Americans.

Interindividual gene copy-number variation (CNV) of complement component C4 and its associated polymorphisms in gene size (long and short) and protein isotypes (C4A and C4B) probably lead to different susceptibilities to autoimmune disease. We investigated the C4 gene CNV in 1,241 European Americans, including patients with systemic lupus erythematosus (SLE), their first-degree relatives, and unrelated healthy subjects, by definitive genotyping and phenotyping techniques. The gene copy number (GCN) varied from 2 to 6 for total C4, from 0 to 5 for C4A, and from 0 to 4 for C4B. Four copies of total C4, two copies of C4A, and two copies of C4B were the most common GCN counts, but each constituted only between one-half and three-quarters of the study populations. Long C4 genes were strongly correlated with C4A (R=0.695; P<.0001). Short C4 genes were correlated with C4B (R=0.437; P<.0001). In comparison with healthy subjects, patients with SLE clearly had the GCN of total C4 and C4A shifting to the lower side. The risk of SLE disease susceptibility significantly increased among subjects with only two copies of total C4 (patients 9.3%; unrelated controls 1.5%; odds ratio [OR] = 6.514; P=.00002) but decreased in those with > or =5 copies of C4 (patients 5.79%; controls 12%; OR=0.466; P=.016). Both zero copies (OR=5.267; P=.001) and one copy (OR=1.613; P=.022) of C4A were risk factors for SLE, whereas > or =3 copies of C4A appeared to be protective (OR=0.574; P=.012). Family-based association tests suggested that a specific haplotype with a single short C4B in tight linkage disequilibrium with the -308A allele of TNFA was more likely to be transmitted to patients with SLE. This work demonstrates how gene CNV and its related polymorphisms are associated with the susceptibility to a human complex disease.

Normal scores for nine maneuvers of the Childhood Myositis Assessment Scale.

OBJECTIVE: To document and evaluate the scores that normal, healthy children achieve when performing 9 maneuvers of the Childhood Myositis Assessment Scale (CMAS). METHODS: A total of 303 healthy children, 4-9 years of age, were scored as they performed 9 CMAS maneuvers. The data were then evaluated to determine whether normal scores for some maneuvers are age and sex dependent. RESULTS: All children were able to achieve maximum possible scores for the supine to prone, supine to sit, floor sit, floor rise, and chair rise maneuvers. All but 2 4-year-olds achieved a maximum possible score for the arm raise/duration maneuver. Performance of the head lift and sit-up maneuvers varied significantly, depending primarily on age. Children in all age groups had less difficulty performing the leg lift than the head lift or sit-up. CONCLUSION: The normative data generated by this study are of value for interpreting the serial CMAS scores of children with idiopathic inflammatory myopathies.

Determining the one, two, three, or four long and short loci of human complement C4 in a major histocompatibility complex haplotype encoding C4A or C4B proteins.

The complex genetics of human complement C4 with unusually frequent variations in the size and number of C4A and C4B, as well as their neighboring genes, in the major histocompatibility complex has been a hurdle for accurate epidemiological studies of diseases associated with C4. A comprehensive series of novel or improved techniques has been developed to determine the total gene number of C4 and the relative dosages of C4A and C4B in a diploid genome. These techniques include (1) definitive genomic restriction-fragment-length polymorphisms (RFLPs) based on the discrete duplication patterns of the RCCX (RP-C4-CYP21-TNX) modules and on the specific nucleotide changes for C4A and C4B isotypes; (2) module-specific PCR to give information on the total number of C4 genes by comparing the relative quantities of RP1- or TNXB-specific fragments with TNXA-RP2 fragments; (3) labeled-primer single-cycle DNA polymerization procedure of amplified C4d genomic DNA for diagnostic RFLP analysis of C4A and C4B; and (4) a highly reproducible long-range-mapping method that employs PmeI-digested genomic DNA for pulsed-field gel electrophoresis, to yield precise information on the number of long and short C4 genes in a haplotype. Applications of these vigorously tested techniques may clarify the roles that human C4A and C4B gene-dosage variations play in infectious and autoimmune diseases.

Genetic sophistication of human complement components C4A and C4B and RP-C4-CYP21-TNX (RCCX) modules in the major histocompatibility complex.

Human populations are endowed with a sophisticated genetic diversity of complement C4 and its flanking genes RP, CYP21, and TNX in the RCCX modules of the major histocompatibility complex class III region. We applied definitive techniques to elucidate (a) the complement C4 polymorphisms in gene sizes, gene numbers, and protein isotypes and (b) their gene orders. Several intriguing features are unraveled, including (1) a trimodular RCCX haplotype with three long C4 genes expressing C4A protein only, (2) two trimodular haplotypes with two long (L) and one short (S) C4 genes organized in LSL configurations, (3) a quadrimodular haplotype with four C4 genes organized in a SLSL configuration, and (4) another quadrimodular structure, with four long C4 genes (LLLL), that has the human leukocyte antigen haplotype that is identical to ancestral haplotype 7.2 in the Japanese population. Long-range PCR and PshAI-RFLP analyses conclusively revealed that the short genes from the LSL and SLSL haplotypes are C4A. In four informative families, an astonishingly complex pattern of genetic diversity for RCCX haplotypes with one, two, three and four C4 genes is demonstrated; each C4 gene may be long or short, encoding a C4A or C4B protein. Such diversity may be related to different intrinsic strengths among humans to defend against infections and susceptibilities to autoimmune diseases.