Lysosomal Storage Disorders in Egyptian Children.

OBJECTIVE: To describe the spectrum, relative prevalence and molecular background of lysosomal storage disorders in Egypt. METHODS: The authors evaluated the selective screening program for the diagnosis of lysosomal storage disorders in Egyptian children presenting to the inherited metabolic disease unit at Cairo University Children's Hospital, the largest tertiary care pediatric hospital in Egypt, over a six-year period (April 2008 through April 2014). During this period, 1,065 suspected children were assessed clinically, biochemically and some genetically. RESULTS: Two hundred and eleven children (aged 44 ± 32 mo; 56 % boys, 82 % with consanguineous parents) were confirmed with 21 different lysosomal disorders. The diagnostic gap ranged between 2 mo and 14 y (average 25 mo). Mucopolysaccharidoses were the most common group of diseases diagnosed (44.5 %), while Maroteaux-Lamy, Gaucher and nephropathic cystinosis were the most commonly detected syndromes (17.1, 14.7 and 13.7 %, respectively). Eighty mutant alleles and 17 pathogenic mutations were detected in 48 genetically assessed confirmed patients (30 Gaucher, 16 cystinosis and two Niemann-Pick type C patients). CONCLUSIONS: This report is the first to describe relative frequency and spectrum of clinical and molecular data in a large cohort of Egyptian lysosomal patients. The crude estimate denotes that over 80 % of Egyptian lysosomal patients do not have access to optimal diagnosis. Upgrading diagnostic and genetic services for lysosomal storage disorders in Egypt is absolutely necessary.

Inborn errors of metabolism detectable by tandem mass spectrometry in Egypt: The first newborn screening pilot study.

OBJECTIVES: To estimate the burden of metabolic disorders detectable by tandem mass spectrometry in Egypt, through a pilot expanded newborn screening programme at Cairo University Children's Hospital in 2008, and examining the results of 3,900 clinically at-risk children, investigated at Cairo University Children's Hospital for the same disorders over the past 7 years using the same technology. METHODS: Dried blood spots of 25,276 healthy newborns from three governorates in Upper, Middle, and Lower Egypt were screened, to give a representative sample of the Egyptian newborn population. Based on the pilot study outcomes and the results of clinically suspected children, we estimated the total birth prevalence of tandem mass spectrometry detectable metabolic disorders, and the relative frequency of several individual disorders. RESULTS: Among the healthy newborns, 13 metabolic disorder cases (five phenylketonuria [1:5,000], two methylmalonic acidemia, and isovaleric acidemia [1:12,500], one each of maple syrup urine disease, propionic acidemia, ß-ketothiolase deficiency, and primary carnitine deficiency [1:25,000]) were confirmed, giving a total birth prevalence of 1:1944 live births. Among the clinically suspected children, 235 cases were diagnosed, representing a much wider disease spectrum. CONCLUSIONS: Egypt has one of the highest reported birth prevalence rates for metabolic disorders detectable by tandem mass spectrometry. Early diagnosis and management are crucial for the survival and well-being of affected children. A nationwide NBS programme by tandem mass spectrometry is recommended.

Clinical utility of chitotriosidase enzyme activity in nephropathic cystinosis.

BACKGROUND: Nephropathic cystinosis is an inherited autosomal recessive lysosomal storage disorder characterized by the pathological accumulation and crystallization of cystine inside different cell types. WBC cystine determination forms the basis for the diagnosis and therapeutic monitoring with the cystine depleting drug (cysteamine). The chitotriosidase enzyme is a human chitinase, produced by activated macrophages. Its elevation is documented in several lysosomal storage disorders. Although, about 6% of Caucasians have enzyme deficiency due to homozygosity of 24-bp duplication mutation in the chitotriosidase gene, it is currently established as a screening marker and therapeutic monitor for Gaucher's disease. METHODS: Plasma chitotriosidase activity was measured in 45 cystinotic patients, and compared with 87 healthy controls and 54 renal disease patients with different degrees of renal failure (CKD1-5). Chitotriosidase levels were also correlated with WBC cystine in 32 treated patients. Furthermore, we incubated control human macrophages in-vitro with different concentrations of cystine crystals and monitored the response of tumor necrosis factor-alpha (TNF-α) and chitotriosidase activity. We also compared plasma chitotriosidase activity in cystinotic knocked-out (n = 10) versus wild-type mice (n = 10). RESULTS: Plasma chitotriosidase activity in cystinotic patients (0-3880, median 163 nmol/ml/h) was significantly elevated compared to healthy controls (0-90, median 18 nmol/ml/h) and to CKD patients (0-321, median 52 nmol/ml/h), P < 0.001 for both groups. Controls with decreased renal function had mild to moderate chitotriosidase elevations; however, their levels were significantly lower than in cystinotic patients with comparable degree of renal insufficiency. Chitotriosidase activity positively correlated with WBC cystine content for patients on cysteamine therapy (r = 0.8), P < 0.001. In culture, human control macrophages engulfed cystine crystals and released TNF-α into culture supernatant in a crystal concentration dependent manner. Chitotriosidase activity was also significantly increased in macrophage supernatant and cell-lysate. Furthermore, chitotriosidase activity was significantly higher in cystinotic knocked-out than in the wild-type mice, P = 0.003. CONCLUSIONS: This study indicates that cystine crystals are potent activators of human macrophages and that chitotriosidase activity is a useful marker for this activation and a promising clinical biomarker and therapeutic monitor for nephropathic cystinosis.

Molecular copro-prevalence of Cryptosporidium in Egyptian children and evaluation of three diagnostic methods.

OBJECTIVE: To determine molecular prevalence of Cryptosporidium in a cohort of Egyptian children and compare three diagnostic tests. METHODS: Stool samples from children with diarrhea (n=150) and from apparently healthy children (n=100) were examined for Cryptosporidium using microscopy, enzyme linked immuosorbant assay (ELISA) and nested polymerase chain reaction (nPCR). RESULTS: nPCR detected Cryptosporidium in 22.4% of children. Acid-fast stain and ELISA showed false negativity but 100% specificity with nPCR as gold standard. CONCLUSION: Cryptosporidium is a common cause of diarrhea in children in Egypt.

Selective screening for inborn errors of metabolism by tandem mass spectrometry in Egyptian children: a 5 year report.

OBJECTIVE: In order to enhance awareness and promote registry for inborn errors of metabolism (IEMs) in Egypt, we aimed to evaluate the prevalence and main clinical findings of IEMs detectable by tandem mass spectrometry (MS/MS) among high risk pediatric patients presenting to our tertiary care facility at Cairo University Children's Hospital over a period of 5 years and to compare the disease burden in Egypt in the absence of a national screening program for inherited metabolic disorders with other populations. METHODS: During this period 3380 Egyptian children were suspected of having IEMs based on clinical/laboratory presentation and were analyzed by MS/MS. Confirmatory testing was performed according to flagged analyte by MS/MS using a different sample type such as plasma or urine or by a different technique such as GC/MS. RESULTS: A relatively high number of patients (203/3380 (6%)) were confirmed with 17 different types of IEMs. Averages for age at diagnosis for different disorders ranged from 2.5 months to 6.6 years with general developmental delay and irreversible neurological damage being the most common presenting features (75.9% and 65.5%, respectively). Amino acid disorders (127/203 (62.6%)), mainly phenylketonuria (100/203 (49.3%)), were the most encountered, followed by organic acidemias (69/203 (34%)), while fatty acid oxidation defects (7/203 (3.4%)) were relatively rare. 88% of patients were born to consanguineous parents. CONCLUSIONS: The development of a nationwide screening program for IEMs is mandatory for early detection of these potentially treatable disorders, prompt and properly timed therapeutic intervention and prevention of the devastating neurological outcomes.