Kathryn L. Berrier

CRIM-negative infantile Pompe disease: characterization of immune responses in patients treated with ERT monotherapy

Purpose:Enzyme replacement therapy (ERT) with recombinant human acid α-glucosidase (rhGAA) prolongs survival in infantile Pompe disease (IPD). However, the majority of cross-reactive immunologic material (CRIM)–negative (CN) patients have immune responses with significant clinical decline despite continued ERT. We aimed to characterize immune responses in CN patients with IPD receiving ERT monotherapy.Methods:A chart review identified 20 CN patients with IPD treated with ERT monotherapy for ≥6 months. Patients were stratified by anti-rhGAA antibody titers: high sustained antibody titers (HSAT; ≥51,200) at least twice; low titers (LT; <6,400) throughout treatment; or sustained intermediate titers (SIT; 6,400–25,600).Results:Despite early initiation of treatment, the majority (85%) of CN patients developed significant antibody titers, most with HSAT associated with invasive ventilation and death. Nearly all patients with HSAT had at least one nonsense GAA mutation, whereas the LT group exclusively carried splice-site or frameshift mutations. Only one patient in the HSAT group is currently alive after successful immune modulation in the entrenched setting.Conclusion:Immunological responses are a significant risk in CN IPD; thus induction of immune tolerance in the naive setting should strongly be considered. Further exploration of factors influencing immune responses is required, particularly with the advent of newborn screening for Pompe disease.Genet Med 17 11, 912–918.

National Down Syndrome Patient Database: Insights From the Development of a Multi-Center Registry Study

The Down Syndrome Study Group (DSSG) was founded in 2012 as a voluntary, collaborative effort with the goal of supporting evidenced‐based health care guidelines for individuals with Down syndrome (DS). Since then, 5 DS specialty clinics have collected prospective, longitudinal data on medical conditions that co‐occur with DS. Data were entered by clinical staff or trained designees into the National Down Syndrome Patient Database, which we created using REDCap software. In our pilot year, we enrolled 663 participants across the U.S., ages 36 days to 70 years, from multiple racial and ethnic backgrounds. Here we report: (i) the demographic distribution of participants enrolled, (ii) a detailed account of our database infrastructure, and (iii) lessons learned during our pilot year to assist future researchers with similar goals for other patient populations.

Sustained immune tolerance induction in enzyme replacement therapy–treated CRIM-negative patients with infantile Pompe disease

BACKGROUND Cross-reactive immunological material-negative (CRIM-negative) infantile Pompe disease (IPD) patients develop an immune response against enzyme replacement therapy (ERT) with alglucosidase alfa that nullifies ERT efficacy. Prophylactic immune tolerance induction (ITI) with rituximab, methotrexate, and IVIG successfully prevents development of deleterious rhGAA IgG antibodies; however, safety, likelihood of success, and long-term efficacy of ITI in a larger cohort remain unknown. METHODS Clinical data were analyzed for 19 CRIM-negative IPD patients who received ITI with rituximab, methotrexate, and IVIG in the ERT-naive setting (ERT+ITI) and compared to a historical cohort of 10 CRIM-negative IPD patients on ERT monotherapy. RESULTS ITI was safely tolerated, although infections were reported in 4 patients. Fourteen (74%) ERT+ITI patients were alive, with a median age of 44.2 months at their final assessment. The eldest survivor was 103.9 months old, with 100.2 months of follow-up after initiation of ERT+ITI. Death (n = 5) occurred at a median age of 29.2 months and was unrelated to the administration of ITI. Fifteen patients either did not seroconvert (n = 8) or maintained low titers (n = 7; defined as titers of ≤6,400 throughout the course of ERT) following ERT+ITI. Only one patient developed high and sustained antibody titers (defined as titers of ≥51,200 at or beyond 6 months on ERT). Left ventricular mass index (LVMI) decreased from a median of 248.5 g/m2 at baseline to 76.8 g/m2 at a median time from ERT+ITI initiation to 59 weeks. ERT+ITI significantly improved overall survival (P = 0.001), eliminated/reduced antibodies at values of ≤6,400 at week 52 on ERT (P = 0.0004), and improved LVMI at week 52 on ERT (P = 0.02) when compared with ERT monotherapy. CONCLUSION Evidence from this international cohort of CRIM-negative IPD patients further supports the safety, feasibility, and efficacy of ITI in the prevention of immune responses to ERT. TRIAL REGISTRATION Clinicaltrials.gov NCT01665326. FUNDING This research was supported in part by the Lysosomal Disease Network, a part of NIH Rare Diseases Clinical Research Network, and by a grant from Genzyme, a Sanofi company.

A Qualitative Study of Factors Influencing Decision-Making after Prenatal Diagnosis of down Syndrome

Previous research has identified twenty-six factors that may affect pregnancy management decisions following prenatal diagnosis of DS; however, there is no consensus about the relative importance or effects of these factors. In order to better understand patient decision-making, we conducted expansive cognitive interviews with nine former patients who received a prenatal diagnosis of DS. Our results suggest that patients attached unique meanings to factors influencing decision-making regardless of the pregnancy outcome. Nineteen of the twenty-six factors previously studied and four novel factors (rationale for testing, information quality, pregnancy experience, and perception of parenting abilities and goals) were found to be important to decision-making. We argue that qualitative studies can help characterize the complexity of decision-making following prenatal diagnosis of DS.

Thyroid dysfunction in patients with Down syndrome: Results from a multi-institutional registry study

The goals of this undertaking were to assess the outcomes of thyroid screening tests and adherence to thyroid screening guidelines across five Down syndrome (DS) specialty clinics in various states. Data related to thyroid screening were collected for 663 individuals across five clinics specializing in the comprehensive care of individuals with DS for a period of 1 year. Of the 663 participants, 47.7% of participants had a TSH and free T4 ordered at their DS specialty clinic visit. Approximately 19.0% (60/316) had a new thyroid disorder diagnosis made. We conclude that a sizable proportion of the patients with DS are not up‐to‐date on current guidelines when they present to a DS specialty clinic, while adherence to thyroid screening guidelines helps facilitate early diagnoses. Hypothyroidism is prevalent in the population, consistent with reported literature. DS specialty clinics can help patients stay current on screening guidelines.

Clinical laboratory experience of blood CRIM testing in infantile Pompe disease

Cross-reactive immunological material (CRIM) status is an important prognostic factor in patients with infantile Pompe disease (IPD) being treated with enzyme replacement therapy. Western blot analysis of cultured skin fibroblast lysates has been the gold standard for determining CRIM status. Here, we evaluated CRIM status using peripheral blood mononuclear cell (PBMC) protein. For 6 of 33 patients (18%) CRIM status determination using PBMC was either indeterminate or discordant with GAA genotype or fibroblast CRIM analysis results. While the use of PBMCs for CRIM determination has the advantage of a faster turnaround time, further evaluation is needed to ensure the accuracy of CRIM results.

Detecting celiac disease in patients with Down syndrome.

The main purposes of this undertaking were to determine how often patients with Down syndrome (DS) are screened for celiac disease (CD) across five DS specialty clinics, which symptoms of CD are most often reported to DS specialty providers at these clinics, and, how many individuals were diagnosed with CD by these clinics. This was accomplished by following 663 individuals with DS for 1 year, across five clinics in different states specializing in the comprehensive care of people with DS. Of the 663 participants, 114 individuals were screened for CD at their visit to a DS specialty clinic. Protracted constipation (43.2%) and refractory behavioral problems (23.7%) were symptoms most often reported to DS specialty providers. During the 1 year study period, 13 patients screened positive for CD by serology. Of those, eight underwent duodenal biopsy, and three were diagnosed with CD. We conclude that CD is an important consideration in the comprehensive care of individuals with DS. However, while symptoms are common, diagnoses are infrequent in DS specialty clinics.

Immunological Factors in Pompe Disease Management: Clinical Experience and Implications for Newborn Screening

Enzyme replacement therapy (ERT) with alglucosidase alfa has improved clinical outcomes and prolonged survival for patients with infantile Pompe disease (IPD). However, patients characterised as Cross-Reactive Immunological Material (CRIM)negative (CN) mount an immune response against ERT resulting in clinical decline and, ultimately, death. A prophylactic immune tolerance induction (ITI) protocol has been successful in preventing the development of antibody titres for these patients. A subset of (CP) patients also mount an immune response with poor clinical outcomes, these at-risk patients are diffi cult to identify. With the advent of newborn screening for Pompe disease, preventative treatment to circumvent an immune response is warranted; therefore, our study aimed to assess the safety and effi cacy of prophylactic ITI in the naive setting for both CP and CN IPD patients.