Critical assessment of chitotriosidase analysis in the rational laboratory diagnosis of children with Gaucher disease and Niemann-Pick disease type A/B and C.

Laboratory diagnosis of lysosomal storage disorders, especially sphingomyelinase deficiency (Niemann-Pick disease type A/B) and Niemann-Pick disease type C (NPC) can be challenging. We therefore aimed to analyse the feasibility of first-step screening with specific chitotriosidase cut-off values in children

IgA nephropathy in two adolescent sisters heterozygous for Fabry disease.

We report a 16-year-old girl and her one-year-younger sister, both heterozygous for the c.34del24 mutation of the GLA (alpha-galactosidase A) gene, which they inherited from their father who is affected by Fabry disease (FD). Both girls presented with macrohematuria and rapidly progressing proteinuria. Urine analysis revealed glomerular hematuria and a nephrotic range of proteinuria suggesting a concomitant glomerulonephritis. Light microscopy of kidney biopsy was characteristic of IgA nephropathy (IgA deposits in mesangial areas and glomerular capillary loops, and mesangial hypercellularity), whereas electron microscopy showed changes typical of Fabry disease (multiple osmiophilic inclusions in the subendothelial and mesangial areas). These two cases and similar reports in the literature suggest that IgA nephropathy in FD is not merely coincidental.

Chronic renal failure and proteinuria in adulthood: Fabry disease predominantly affecting the kidneys.

The prognosis of Fabry disease has changed since enzyme-replacement treatment was introduced. Therefore, early diagnosis is instrumental. We describe a family presenting with chronic renal failure and proteinuria in which classic skin and neurological features were absent and the diagnosis of Fabry disease was difficult and not established until a second family member developed renal abnormalities. A 35-year-old man was admitted because he was overweight and had hypertension, with a serum creatinine level of 1.3 mg/dL (115 micromol/L) and protein excretion of 870 mg/d. Because 1 brother, who died years ago at the age of 32 years of acute myeloid leukemia, also had chronic renal failure and proteinuria, the diagnosis of Fabry disease was entertained. In the index patient, acroparesthesia, hypohidrosis, pain, angiokeratomas of the skin, and cornea verticillata suggesting Fabry disease were absent. Conversely, renal biopsy showed typical globotriaosylceramide deposits, and leukocyte alpha-galactosidase (alpha-GLA) A activity was decreased. Analysis of the alpha-GLA gene showed the mutation E66K. The mutation also was found in another asymptomatic 30-year-old brother who also had chronic renal failure and proteinuria, but normal extrarenal findings. In the brother who died, Fabry disease, missed at autopsy because of cancer-related findings, could be confirmed after repeated review of histological slides. Mutation carriers also included the mother, a sister (both without abnormalities), and a nephew (with episodic pains in his feet). We conclude that familial chronic renal failure combined with proteinuria is suggestive of Fabry disease, and such specific mutations as E66K predominantly may affect the kidneys.

Pediatric Fabry disease.

BACKGROUND: Fabry disease is an underdiagnosed, treatable, X-linked, multisystem disorder. OBJECTIVES: To test the hypothesis that quality of life and sweating are decreased among pediatric patients with Fabry disease, compared with control subjects, and to provide quantitative natural history data and novel clinical end points for therapeutic trials. DESIGN: Prospective, cross-sectional, observational study. SETTING: Referral to the National Institutes of Health. PARTICIPANTS: Twenty-five male children with Fabry disease (mean age: 12.3 +/- 3.5 years) and 21 age-matched control subjects. MAIN OUTCOME MEASURES: Quality of life (measured with the Child Health Questionnaire) and sweating (assessed with the quantitative sudomotor axon reflex test). RESULTS: Quality of life scores for pediatric patients <10 years of age with Fabry disease, compared with published normative values, were 55 +/- 17 vs 83 +/- 19 for bodily pain and 62 +/- 19 vs 80 +/- 13 for mental health. Bodily pain scores for patients > or =10 years of age were 54 +/- 22 vs 74 +/- 23. Sweat volume in the Fabry disease group was 0.41 +/- 0.46 microL/mm2, compared with 0.65 +/- 0.44 microL/mm2 in the control group. Renal function, urinary protein excretion, and cardiac function and structure were normal for the majority of patients. The 3 patients with residual alpha-galactosidase A activity > or =1.5% of normal values were free of cornea verticillata and had normal serum and urinary globotriaosylceramide levels. All other children had glycolipid levels comparable to those of adult patients with Fabry disease. Acroparesthesia and cardiac abnormalities were generally present before anhidrosis and proteinuria. Mapping of the missense mutations on the crystallographic structure of alpha-galactosidase A revealed that the mutations were partially surface-exposed and distal to the active site among individuals with residual enzyme activity. Mutations associated with left ventricular hypertrophy (defined as left ventricular mass index of >51 g/m2.7) were localized near the catalytic site of the enzyme. CONCLUSIONS: Despite the absence of major organ dysfunction, Fabry disease demonstrates significant morbidity already in childhood. We have identified important, potentially correctable or preventable, outcome measures for future therapeutic trials. Prevention of complications involving major organs should be the goal for long-term specific therapy.