Novel Sequence Variants in the NPC1 Gene in Egyptian Patients with Niemann-Pick Type C

BACKGROUND: Niemann-Pick disease type C (NPC) is a rare, autosomal recessive, progressive neuro-visceraldisease caused by biallelic mutations in either NPC1gene (95% of cases) or NPC2 gene. AIM: This caseseries study aimed at the molecular analysis of certain hot spots of NPC1 genein NPC Egyptian patients. METHODS: The study included 15 unrelated NPC patients and selected parents,as well as20 healthy controls of matched sex and age. Clinical investigations were performed according to well established clinical criteria. Assessment of the chitotriosidase level, as an initial screening tool for NPC, was done in all cases. Polymerase chain reaction amplification of NPC1 exons (17–25) encountering the hotspot residues (855–1098 and1038–1253) was carried out followed by direct sequencingfor mutational analysis. RESULTS: All includedpatients with mainly neurovisceral involvement were characterized. The onset of the disease varied from early-infantile (58.3%) to late-infantile (26.7%) and juvenile-onset (6.7%). Ahigh chitotriosidase level wasobservedin all patients. Molecular analysis of NPC1 (exons 17–25) confirmed 15 mutant alleles out of 30 studied ones. They included two novel homozygous missense variants (p.Ser1169Arg and p.Ser1197Phe) and previously reportedfour mutations (p.Arg958*, p.Gly910Ser, p.Ala927Glyfs*38, and andp.Cys1011*). CONCLUSION: The two studied amino acid residues (855–1098 and 1038–1253) could beconsidered aspotential hotspot regions in NPC1 Egyptian patients

Prenatal genetic testing, counseling and follow-up of 33 Egyptian pregnant females with history of mucopolysaccharidoses

Background: Mucopolysaccharidoses (MPS) are autosomal recessive disorders characterized by deficiency of lysosomal enzymes which break down the glycosaminoglycans (GAGs) which results in widespread intra and extra-cellular accumulations of GAGs. Early initiation of treatment, before the onset of irreversible tissue damage, clearly provides a favorable disease outcome. Early detection might be afforded by analysis of amniotic fluid. Aim: To report our experience of prenatal diagnosis of MPS over 14-year period for cases referred from medical centers throughout Egypt. Also to report the benefit of prenatal genetic testing in cases accompanied with genetic disorders. Materials and methods: The present study included 33 pregnant women at risk of having a fetus with MPS. Of these cases, 3 women had more than one pregnancy evaluated. All cases had a detailed genetic ultrasound examination and a maternal serum alpha-fetoprotein (MSAFP) evaluation during the second trimester of pregnancy. Thirty-eight amniocentesis procedures were performed during the study for 2 dimensional electrophoresis (2-DEP) of GAGs. Results: Positive consanguinity was present in near 70% (23/33) of the couples. Detailed genetic ultrasound examination revealed a case with anencephaly and another one with a twin pregnancy. One case had a MSAFP of 3.6 multiple of the normal median (open neural tube defect). Another 2 cases had a risk of having Down syndrome. Results of the 2-DEP of GAGs in amniotic fluid revealed 36.8% (14/33) affected fetuses. During the final counseling setting of the 14 cases with abnormal results, 43% (6/14) elected to continue their pregnancy while 57% (8/14) elected termination. Conclusion: Early prenatal screening and diagnosis, through a systematic multidisciplinary approach, to all cases of mucopolysaccharidoses are recommended, to improve the quality of life and to avoid the presence of other associated fetal developmental malformations

Mass spectrometry for screening of metabolic disorders: 9-year biochemical genetics experience

Background/aim Inborn errors of metabolism (IEM) are a group of congenital disorders that result from deficiency of enzymes or transporters involved in different metabolic pathways in the human body. The most severe form of these disorders appears early in the neonatal period; however, most types of IEMs are responsive to treatment if started early enough before the appearance of serious complications. The introduction of mass spectrometric techniques for analysis of metabolites accumulated in IEM facilitates the early diagnosis through enabling analysis of a large number of samples in a short period of time using small sample sizes suitable for patients in the neonatal period. The aim of this study was to find out the prevalence of amino acids, fatty acids, and organic acids disorders, using mass spectrometry among Egyptian children with metabolic disorders who were referred to the Biochemical Genetics Lab, Human Genetics, and Genome Research Institute, National Research Centre, Cairo, Egypt, over a period of 9 years. Patients and methods The present study enrolled 9245 children who visited Biochemical Genetics Department, Human Genetics, and Genome Research Institute, National Research Centre Cairo, Egypt, during the period from 2013 to 2021. All children were subjected to quantitative analysis of amino acids and acylcarnitine profiles in blood, using liquid chromatography/tandem mass spectrometry, whereas qualitative analysis of organic acids was done in urine by gas chromatography/mass spectrometry. Results Of 9245 suspected patients, 552 (5.97%) patients were diagnosed with 13 different types of IEM. A total of 383 (4.1%) patients were diagnosed with aminoacidopathies, 167 (1.8%) patients were diagnosed with organic acidurias, and two (0.02%) patients were diagnosed with fatty acid oxidation disorders. Phenylketonuria is the most prevalent IEM of this study (2%) followed by maple syrup urine disease (0.98%). Conclusion The simultaneous analysis of amino acids and acylcarnitines in dried blood spots with analysis of organic acids in urine using mass spectrometry provides an integrated panel for the early detection of IEMs in early years of life, facilitating prompt provision of treatment and avoiding serious complications that can be fatal

Quaternary diagnostics scheme for mucolipidosis II and detection of novel mutation in GNPTAB gene

Abstract Background Mucolipidosis II (ML II α/β) is an inherited lysosomal storage disorder caused by deficiency of GlcNAc-phosphotransferase enzyme and results in mis-targeting of multiple lysosomal enzymes. Affected patients are characterized by skeletal deformities and developmental delay. Homozygous or compound heterozygous mutations in GNPTAB gene are associated with the clinical presentation. This is the first study to characterize the underlying genetics of ML among a cohort of Egyptian patients. ML II diagnosis established by clinical assessment, biochemical evaluation of enzymes, electron microscopy examination of gingival inclusion bodies, and molecular study of GNPTAB gene using targeted next-generation sequencing panel in 8 patients form 8 unrelated Egyptian families. Results Sequencing revealed 3 mutations in GNPTAB gene; 1 novel frame-shift mutation in exon 19 (c.3488_3488delC) and 2 previously reported mutations (c.1759C>T in exon 13 and c.3503_3504delTC in exon 19). All patients were homozygous for their corresponding mutations and the parents were consanguineous. Conclusions According to the established quaternary diagnostic scheme, ML II was the final diagnosis in eight patients. The most common mutation was the frame shift c.3503_3504delTC mutation, found in 5 patients and associated with a severe phenotype

Diagnosis and management of patients with Gaucher disease: an Egyptian expert opinion

Abstract Background Gaucher disease (GD), an autosomal recessive, lysosomal storage disorder, is caused due to mutations in the glucocerebrosidase (GBA) gene. GD can occur at any age and is classified as type 1 (non-neurologic), type 2 (infantile form, with acute early neurologic manifestation), and type 3 (subacute/chronic neuropathic form). The rarity of the disease and its overlapping symptoms with other diseases increase the delay in diagnosis. The Egyptian cohort of patients with GD is specifically different regarding the prevalence of type 3 as well as the severity and progression of the disease. The unavailability of precise diagnostic tests and lack of awareness among clinicians are the current challenges associated with diagnosing and managing GD in Egypt. Method An expert panel meeting was convened with 19 experts from Egypt to address the current unmet challenges in the diagnosis and management of GD from the region and to develop country-specific diagnostic algorithms based on the existing literature for pediatric and adult groups. In addition, management strategies and preventive measures were also discussed. Result The algorithms presented in this review can be implemented in clinical practice for the timely diagnosis of patients with GD in Egypt. Early diagnosis is crucial in selecting the best treatment for patients with GD, and evidence suggests that early initiation of therapy can result in better outcomes. Conclusion The evidence-based expert opinion presented in this review will help clinicians in the early initial diagnosis of GD in Egypt, leading to appropriate management of the disease