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N Tayebi

Publications and source records attributed to N Tayebi.

28 records · Page 2Linked to original sources
PubMed1997

Identification of three additional genes contiguous to the glucocerebrosidase locus on chromosome 1q21: implications for Gaucher disease.

Gaucher disease results from the deficiency of the lysosomal enzyme glucocerebrosidase (EC 3.2.1.45). Although the functional gene for glucocerebrosidase (GBA) and its pseudogene (psGBA), located in close proximity on chromosome 1q21, have been studied extensively, the flanking sequence has not been well characterized. The recent identification of human metaxin (MTX) immediately downstream of psGBA prompted a closer analysis of the sequence of the entire region surrounding the GBA gene. We now report the genomic DNA sequence and organization of a 75-kb region around GBA, including the duplicated region containing GBA and MTX. The origin and endpoints of the duplication leading to the pseudogenes for GBA and MTX are now clearly established. We also have identified three new genes within the 32 kb of sequence upstream to GBA, all of which are transcribed in the same direction as GBA. Of these three genes, the gene most distal to GBA is a protein kinase (clk2). The second gene, propin1, has a 1.5-kb cDNA and shares homology to a rat secretory carrier membrane protein 37 (SCAMP37). Finally, cote1, a gene of unknown function lies most proximal to GBA. The possible contributions of these closely arrayed genes to the more atypical presentations of Gaucher disease is now under investigation.

Carrier Proteins↗
PubMed1996

55-base pair deletion in certain patients with Gaucher disease complicates screening for common Gaucher alleles.

Mutations in the glucocerebrosidase gene which result in Gaucher disease can originate from the highly homologous glucocerebrosidase pseudogene. A 55-bp deletion in exon 9, which corresponds to a 55-bp segment absent from the pseudogene, has been identified in patients with Gaucher disease. We have developed a simple polymerase chain reaction (PCR)-based method to detect this 55-bp deletion, and have found this mutation in 3 of 75 DNA samples (4%) collected from patients with Gaucher disease. Commonly used PCR-based screening methods for specific Gaucher mutations frequently make use of primers either within or surrounding the 55-bp gap to selectively distinguish the glucocerebrosidase gene from the pseudogene. However, if the 55-bp deletion in exon 9 occurs, primers will either fail to produce an amplification product or will produce a shortened product which will be falsely attributed to the pseudogene. This could lead to inaccurate genotyping and genetic counseling for some Gaucher patients and their families. We therefore recommended that laboratories using PCR-based screening techniques involving primers in this region initially determine whether this 55-bp sequence is present.

Alleles↗
PubMed1996

cDNA cloning and characterization of the human interleukin 13 receptor alpha chain.

We have cloned cDNAs corresponding to the human interleukin 13 receptor alpha chain (IL-13Ralpha). The protein has 76% homology to murine IL-13Ralpha, with 95% amino acid identity in the cytoplasmic domain. Only weak IL-13 binding activity was found in cells transfected with only IL-13Ralpha; however, the combination of both IL-13Ralpha and IL-4Ralpha resulted in substantial binding activity, with a Kd of approximately 400 pM, indicating that both chains are essential components of the IL-13 receptor. Whereas IL-13Ralpha serves as an alternative accessory protein to the common cytokine receptor gamma chain (gammac) for IL-4 signaling, it could not replace the function of gammac in allowing enhanced IL-2 binding activity. Nevertheless, the overall size and length of the cytoplasmic domain of IL-13Ralpha and gammac are similar, and like gammac, IL-13Ralpha is located on chromosome X.

Amino Acid Sequence↗
PubMed1996

The clinical, molecular, and pathological characterisation of a family with two cases of lethal perinatal type 2 Gaucher disease.

It has recently been emphasised that a subset of patients with type 2 Gaucher disease die in the neonatal period. This report describes an Afghani family with two conceptuses having severe, prenatally detected Gaucher disease. Mutational analysis showed that the family carried a known complex allele which included mutations at amino acids L444P, A456P, and V460V. Although glucocerebrosidase RNA was present, an affected fetus had virtually no glucocerebrosidase cross reactive material on western analyses. The severe clinical course and pathology observed in these patients resemble that of the null allele Gaucher mouse, and suggest that the absence of glucocerebrosidase activity results in early death.

Afghanistan↗
PubMed1995

Congenital ichthyosis preceding neurologic symptoms in two sibs with type 2 Gaucher disease.

We describe 2 sibs who presented with ichthyotic skin at birth and subsequently developed neurologic manifestations of type 2 Gaucher disease. Type 2 Gaucher patients with and without ichthyosis manifest ultrastructural and biochemical abnormalities in the epidermis. The 2 patients described here clearly demonstrate that epidermal involvement in type 2 Gaucher disease may precede neurologic symptoms and substantiate the prognostic significance of early skin abnormalities in Gaucher patients. Gaucher disease should be considered in the differential diagnosis of congenital ichthyosis, even if the scaling resolves spontaneously.

Amniocentesis↗
PubMed1995

Mutation of Jak3 in a patient with SCID: essential role of Jak3 in lymphoid development.

Males with X-linked severe combined immunodeficiency (XSCID) have defects in the common cytokine receptor gamma chain (gamma c) gene that encodes a shared, essential component of the receptors of interleukin-2 (IL-2), IL-4, IL-7, IL-9, and IL-15. The Janus family tyrosine kinase Jak3 is the only signaling molecule known to be associated with gamma c, so it was hypothesized that defects in Jak3 might cause an XSCID-like phenotype. A girl with immunological features indistinguishable from those of XSCID was therefore selected for analysis. An Epstein-Barr virus (EBV)-transformed cell line derived from her lymphocytes had normal gamma c expression but lacked Jak3 protein and had greatly diminished Jak3 messenger RNA. Sequencing revealed a different mutation on each allele: a single nucleotide insertion resulting in a frame shift and premature termination in the Jak3 JH4 domain and a nonsense mutation in the Jak3 JH2 domain. The lack of Jak3 expression correlated with impaired B cell signaling, as demonstrated by the inability of IL-4 to activate Stat6 in the EBV-transformed cell line from the patient. These observations indicate that the functions of gamma c are dependent on Jak3 and that Jak3 is essential for lymphoid development and signaling.

Amino Acid Sequence↗
PubMed1995

Diagnosing Gaucher disease. Early recognition, implications for treatment, and genetic counseling.

The diagnosis of Gaucher disease, the inherited deficiency of glucocerebrosidase and the most common inherited disorder of Ashkenazi Jews, can often be missed by clinicians. Medical records from patients with Gaucher disease were reviewed, revealing a wide range of initial misdiagnoses and the frequent use of unnecessary invasive diagnostic procedures. The diagnosis of Gaucher disease is readily established by enzymatic or DNA analyses in conjunction with a thorough history and physical examination. Consequently, greater awareness of the symptoms encountered in these patients could alleviate unnecessary anxiety, testing, and confusion. A definitive diagnosis of Gaucher disease has important implications for genetic counseling and treatment.

Adolescent↗
PubMedDate not supplied

Is the perinatal lethal form of Gaucher disease more common than classic type 2 Gaucher disease?

In recent years there has been increased recognition of a severe perinatal lethal form of Gaucher disease, the inherited deficiency of lysosomal glucocerebrosidase. We previously reported a case of severe type 2 Gaucher disease which was seen in a medical center in Rotterdam and now present three new cases from two other families seen at the same center. Mutational analyses of these cases revealed two novel mutations, H311R and V398F, located in exons 8 and 9, respectively. The identification of four cases of lethal type 2 Gaucher disease in a single center seems to be a function of increased awareness of this phenotype, rather than of geographic clustering. The actual incidence of lethal type 2 Gaucher disease may be underestimated, as many cases may have been misclassified as collodion babies or hydrops of unknown cause.

DNA Mutational Analysis↗