RESUMO
BACKGROUND: Approximately 7-10% of Parkinson's disease (PD) patients carry a GBA (Glucocerebrosidase) mutation (GBA-PD patients), which may influence the disease's clinical course. OBJECTIVES: This study aimed to explore the patient experience of GBA-PD and identify the most important symptoms and impacts to inform clinical trial measurement strategies. METHODS: Twenty PD patients (n = 15 GBA-PD; n = 5 idiopathic-PD) participated in qualitative interviews which explored concepts spontaneously reported or identified through a literature review. Telephone interviews with five expert clinicians included discussion of a preliminary conceptual model derived from literature. Verbatim transcripts were thematically analysed. RESULTS: Thirty symptoms reported by patients were categorized as motor, non-motor, and cognitive/psychiatric. Tremor (n = 13), memory loss (n = 13), rigidity/stiffness (n = 11), and speech problems (n = 11) were considered the most important and impactful symptoms by GBA-PD patients, although other symptoms were also relevant to the majority of patients. Key impacts included: sleep disturbances (n = 13), handwriting changes (n = 13), reduced social interaction (n = 12), dyskinesia (n = 10), depressed mood (n = 9), and fear of falling (n = 8). Key symptoms and impacts reported by GBA-PD patients were consistent with those reported by idiopathic-PD patients. Clinician interview results supported the patient findings, although some clinicians indicated that cognitive/psychiatric symptoms may present earlier in GBA-PD patients. The concepts emerging from the research informed updates to a conceptual model of GBA-PD patients' disease experience. CONCLUSIONS: The findings provide in-depth understanding of the patient experience of GBA-PD. The findings confirm that the concepts relevant to assess in GBA-PD are consistent with those relevant to assess in idiopathic-PD; however, greater consideration of cognitive/psychiatric symptoms may be warranted in GBA-PD populations.
RESUMO
BACKGROUND: Mental retardation and other disabilities (including ectopia lentis, osteoporosis, and thromboembolism) in patients who have homocystinuria as a result of a deficiency of cystathionine beta-synthase can be prevented by the screening of newborns with measurement of blood methionine, followed by the early treatment of affected infants. Many infants with this disorder, however, are not identified by screening and have irreversible brain damage. METHODS: We reviewed the results of neonatal screening for homocystinuria over a period of 32 years in New England. Additional specimens were requested for repeated analysis when blood methionine measurements were at or above the established cutoff level. Homocystinuria due to cystathionine beta-synthase deficiency was confirmed by quantitative amino acid analyses. RESULTS: For the first 23.5 years of the review period, the blood methionine cutoff value was 2 mg per deciliter (134 micromol per liter). Among the 2.2 million infants screened during that period, 8 with homocystinuria were identified (1:275,000). In 1990, the cutoff value was reduced to 1 mg per deciliter (67 micromol per liter). Among the 1.1 million infants screened in the subsequent 8.5 years, 7 with the disorder were identified (1:157,000). During the latter period, the specimens were collected from six of the seven infants when they were two days of age or less; five of the six had blood methionine concentrations below 2 mg per deciliter. Use of the reduced cutoff level increased the false positive rate from 0.006 percent to 0.03 percent. CONCLUSIONS: A cutoff level for blood methionine of 1 mg per deciliter in neonatal screening tests for homocystinuria should identify affected infants who have only slightly elevated concentrations of methionine and reduce the frequency of false negative results.