Urine organic acid as the first clue towards aromatic L-amino acid decarboxylase (AADC) deficiency in a high prevalence area.

BACKGROUND: Aromatic L-amino acid decarboxylase deficiency is a rare neurometabolic disease due to impaired decarboxylation of neurotransmitter precursors to its active form. CASE: We retrospectively reviewed 8 cases from 2008 to 2019 with cerebrospinal fluid neurotransmitter analysis performed at our centre. All cases had an elevated urine vanillactic acid and, in most cases, with N-acetylvanilalanine detected. Cerebrospinal fluid analysis showed low downstream metabolites vanillylmandelic acid, homovanillic acid but high 3-O-methyl-L-DOPA, 5-hydroxytryptophan. Cerebrospinal fluid pterins were normal. Genotyping in DDC confirms the diagnosis. Urine organic acid analysis provided the first clue to diagnosis in four of the cases, which then triggered cerebrospinal fluid neurotransmitter and genetic analysis. We also developed a diagnostic decision support system to assist the interpretation of the mass spectrometry data from urine organic acids. CONCLUSIONS: Urine organic acid could be essential in guiding subsequent investigations for the diagnosis of aromatic L-amino acid decarboxylase deficiency. We propose to screen suspected cases first with urine organic acids, specifically looking for vanillactic acid and N-acetylvanilalanine. Suggestive findings should be followed with target analysis for c.714 + 4A > T in ethnically Chinese patients. The assistive tool allowed expedite interpretation of profile data generated from urine organic acids analysis. It may also reduce interpreter's bias when peaks of interest are minor peaks in the spectrum.

Erratum to: Mutational analysis of 65 Wilson disease patients in Hong Kong Chinese: Identification of 17 novel mutations and its genetic heterogeneity.

The correct name of the eighth author should be given as Sik-To Lai, not Jak-Yiu Lai.

Is there an accurate method to measure metabolic requirement of institutionalized children with spastic cerebral palsy?

OBJECTIVES: This study hypothesized that there is no difference between energy expenditure measured by indirect calorimetry (IC) and that estimated by predicted formulas compared with the actual intake of children with spastic cerebral palsy (CP). METHODS: Fifteen children aged 3 to 18 years with spastic CP and associated complications were recruited. IC was used to measure mean energy expenditure (MEE) compared with 3 predicted equations for energy expenditure (PEE), including body surface area (BSA), the recommended daily allowance (RDA), and an equation designed specifically for patients with CP. Friedman and paired t tests were used to examine the variance between PEE and MEE. Intraclass correlation coefficient (ICC) was used to explore the correlation between MEE and PEE. The pretest and posttest core temperatures were compared using the Wilcoxon signed rank test. RESULTS: Mean ± standard deviation MEE was 800.5 ± 295.7 kcal/d; BSA was 1,213.4 ± 171.2 kcal/d; RDA was 1,928.1 ± 341.0 kcal/d; and CP was 1,603.1 ± 215.8 kcal/d. The actual diet intake provided 935.3 ± 222.9 kcal/d. Post hoc analysis revealed a significant difference between mean MEE and PEE (P < .001) but not mean actual intake (P = .128). In addition, the ICC of MEE vs PEE was 0.635 at a 95% confidence interval, indicating a weak correlation. In addition, mean pretest body temperature was 36.4°C ± 1°C, and mean posttest body temperature was 35.8°C ± 2°C. CONCLUSIONS: The study showed that MEE was significantly different from PEE, but not from actual intake. This warrants further exploration to develop a population-specific PEE for children with spastic CP.

Mutational analysis of 65 Wilson disease patients in Hong Kong Chinese: identification of 17 novel mutations and its genetic heterogeneity.

Wilson disease (WD), an autosomal recessive disorder of copper transport, is the most common inherited liver disorder in Hong Kong Chinese. This was the first local study to elucidate the molecular basis and establish an effective DNA-based diagnostic protocol. The ATP7B genes of 65 patients were amplified by polymerase chain reaction (PCR) and sequenced. Haplotype analysis was performed using D13S301, D13S314, and D13S316. The p.L770L/p.R778L status in 660 subjects was determined to estimate WD prevalence. Allele age of p.R778L was determined by the smallest homozygosity region between D13S301 and D13S270. We identified 42 different mutations with 17 being novel. p.R778L (17.3%) was the most prevalent. Exons 2, 8, 12, 13, and 16 harbored 70% mutations. Thirty-two haplotypes were associated with WD chromosomes. The estimated prevalence rate was 1 in 5,400. Three out of 660 normal subjects had p.L770L/p.R778L. In the remaining 657 individuals, neither p.L770L nor p.R778L was found. We characterized a Hong Kong Chinese-specific ATP7B mutation spectrum with great genetic diversity. Exons 2, 8, 12, 13, and 16 should be screened first. The perfect linkage disequilibrium suggested that p.R778L and its private polymorphism p.L770L originated from a single ancestor. This East-Asian-specific mutation p.R778L/p.L770L is aged at least 5,500 years.

A patient with novel ABCB11 gene mutations with phenotypic transition between BRIC2 and PFIC2.

We describe a PFIC2 patient with a good response to ursodeoxycholic acid for 9 years. We found two novel ABCB11 gene mutations in the patient, i.e. I498T and 2098delA. The correlation of the patient's genotypes with the clinical course supports the existence of a phenotypic continuum between BRIC2 and PFIC2.

Esophageal eosinophilia in children with dysphagia.

OBJECTIVES: Children occasionally have dysphagia in the absence of an apparent primary cause. Esophageal eosinophilia is sometimes seen in these patients at the time of upper endoscopy but its significance is not clear. Although eosinophilia is regarded by some as a histologic hallmark of childhood reflux esophagitis, it may in fact signal a primary eosinophilic esophagitis in children with dysphagia. Our aim was to evaluate esophagitis, acid reflux determined by pH probe, and esophageal eosinophilia in children with the primary complaint of dysphagia. METHODS: A retrospective study was performed in 42 children, admitted for investigation of dysphagia, in whom no primary cause could be found. Twenty-one children (mean age +/- SD, 10.1 +/- 4.0 years) had esophageal eosinophilia and 21 children (8.3 +/- 4.7 years) did not. Clinical, endoscopic, manometric and esophageal pH parameters in these two groups were compared. RESULTS: Patients with esophageal eosinophilia were more often male (p<0.01) with a history of allergy (p<0.001) and food bolus obstruction (p<0.05) requiring endoscopic removal. Their esophageal mucosa appeared wrinkled and thickened at endoscopy with basal cell proliferation, and large numbers of eosinophils in esophageal mucosal biopsies. Continuous esophageal pH records and motility studies, when obtained, were similar in both groups and were within normal values. CONCLUSION: Children with dysphagia who have esophageal eosinophilia are unlikely to have pathologic gastroesophageal reflux.