The challenges of managing coexistent disorders with phenylketonuria: 30 cases.

INTRODUCTION: The few published case reports of co-existent disease with phenylketonuria (PKU) are mainly genetic and familial conditions from consanguineous marriages. The clinical and demographic features of 30 subjects with PKU and co-existent conditions were described in this multi-centre, retrospective cohort study. METHODS: Diagnostic age of PKU and co-existent condition, treatment regimen, and impact of co-existent condition on blood phenylalanine (Phe) control and PKU management were reported. RESULTS: 30 patients (11 males and 19 females), with PKU and a co-existent condition, current median age of 14 years (range 0.4 to 40 years) from 13 treatment centres from Europe and Turkey were described. There were 21 co-existent conditions with PKU; 9 were autoimmune; 6 gastrointestinal, 3 chromosomal abnormalities, and 3 inherited conditions. There were only 5 cases of parental consanguinity. Some patients required conflicting diet therapy (n=5), nutritional support (n=7) and 5 children had feeding problems. There was delayed diagnosis of co-existent conditions (n=3); delayed treatment of PKU (n=1) and amenorrhea associated with Grave's disease that masked a PKU pregnancy for 12 weeks. Co-existent conditions adversely affected blood Phe control in 47% (n=14) of patients. Some co-existent conditions increased the complexity of disease management and increased management burden for patients and caregivers. CONCLUSIONS: Occurrence of co-existent disease is not uncommon in patients with PKU and so investigation for co-existent disorders when the clinical history is not completely consistent with PKU is essential. Integrating care of a second condition with PKU management is challenging.

Niemann-Pick Type C-2 Disease: Identification by Analysis of Plasma Cholestane-3ß,5α,6ß-Triol and Further Insight into the Clinical Phenotype.

INTRODUCTION: Niemann-Pick type C disease is a rare disorder caused by impaired intracellular lipid transport due to mutations in either the NPC1 or the NPC2 gene. Ninety-five % of NPC patients show mutations in the NPC1 gene. A much smaller number of patients suffer from NPC2 disease and present respiratory failure as one of the most frequent symptoms. Several plasma oxysterols are highly elevated in NPC1 and can be used as a biomarker in the diagnosis of NPC1. METHODS: Plasma cholestane-3ß,5α,6ß-triol was evaluated as biomarker for NPC2 by GC/MS and LC-MS/MS analysis. The diagnosis was confirmed by Sanger sequencing and filipin staining. RESULTS: We report three NPC2 patients with typical respiratory problems and a detailed description of the nature of the lung disease in one of them. All patients had elevated levels of plasma cholestane-3ß,5α,6ß-triol. In two of these patients, the positive oxysterol result led to a rapid diagnosis of NPC2 by genetic analysis. The phenotype of the third patient has been described previously. In this patient a cholestane-3ß,5α,6ß-triol concentration markedly above the reference range was found. CONCLUSIONS: Measurement of plasma cholestane-3ß,5α,6ß-triol enables to discriminate between controls and NPC1 and NPC2 patients, making it a valuable biomarker for the rapid diagnosis not only for NPC1 but also for NPC2 disease.The measurement of oxysterols should be well kept in mind in the differential diagnosis of lysosomal diseases, as the elevation of oxysterols in plasma may speed up the diagnosis of NPC1 and NPC2.

Clinical onset and course, response to treatment and outcome in 24 patients with the cblE or cblG remethylation defect complemented by genetic and in vitro enzyme study data.

BACKGROUND: The cobalamin E (cblE) (MTRR, methionine synthase reductase) and cobalamin G (cblG) (MTR, methionine synthase) defects are rare inborn errors of cobalamin metabolism leading to impairment of the remethylation of homocysteine to methionine. METHODS: Information on clinical and laboratory data at initial full assessment and during the course of the disease, treatment, outcome and quality of life was obtained in a survey-based, retrospective study from physicians caring for patients with the CblE or CblG defect. In addition, data on enzyme studies in cultured skin fibroblasts and mutations in the MTRR and MTR gene were analysed. RESULTS: In 11 cblE and 13 cblG patients, failure to thrive, feeding problems, delayed milestones, muscular hypotonia, cognitive impairment and macrocytic anaemia were the most frequent symptoms. Delay in diagnosis depended on age at first symptom and clinical pattern at presentation and correlated significantly with impaired communication abilities at follow-up. Eighteen/22 patients presented with brain atrophy or white matter disease. Biochemical response to treatment with variable combinations of betaine, cobalamin, folate was significant. The overall course was considered improving (n = 8) or stable (n = 15) in 96% of patients, however the average number of CNS symptoms per patient increased significantly over time and 16 of 23 patients were classified as developmentally delayed or severely handicapped. In vitro enzyme analysis data showed no correlation with outcome. Predominantly private mutations were detected and no genotype- phenotype correlations evident. CONCLUSIONS: The majority of patients with the cblE and cblG defect show limited clinical response to treatment and have neurocognitive impairment.