Frequency of the HFE C282Y and H63D mutations in distinct ethnic groups living in Spain.
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Alleles↗
Biomedical subjects
M Baiget
Publications and source records attributed to M Baiget.
p53 mutation in a case of blastic transformation of follicular lymphoma with double bcl-2 rearrangement (MBR and VCR).
The bcl-2 gene is rearranged in most cases of follicular lymphoma and the breakpoint clusters are found in two specific regions: mbr and mcr. Rearrangements of the immunoglobulin heavy chain genes (IgH) result in a deregulation of the gene and increased transcription of mRNA for the bcl-2 protein. In cases of rearrangement of the light chains (variant translocations), a third breakpoint has been described at the 5' part of the bcl-2 locus (vcr). In the present case, we report the molecular analysis of an FL transformed into a blastic phase unresponsive to chemotherapy. Molecular studies revealed a typical bcl-2 rearrangement at the major locus (mbr). Vcr rearrangements was also observed with only a single restriction enzyme. At the same time, SSCP analysis of exon 5 of the p53 locus disclosed an abnormal conformer. Direct sequencing revealed a point mutation at codon 163 (A --> G). Immunohistochemical analysis of the affected sites disclosed overexpression of p53 and bcl-2. It is concluded that p53 mutation can contribute to blastic transformation in cases of follicular lymphomas with double rearrangement at the bcl-2 locus (mbr/vcr).
Blast Crisis↗
Importance of mixed chimerism to predict relapse in persistently BCR/ABL positive long survivors after allogeneic bone marrow transplantation for chronic myeloid leukemia.
Determination of hematological chimerism could be helpful in understanding the biology of leukemic relapse after allogeneic bone marrow transplant (BMT) for chronic myeloid leukemia (CML), because the detection of malignant residual cells carrying the bcr/abl message by qualitative RT-PCR is of limited value in predicting disease progression for individual patients. We have studied the chimerism pattern and the bcr/abl status by Southern-blot in 15 CML patients (M/F:6/9) transplanted with unmanipulated BM from HLA identical sibling donors, persistently bcr/abl positive by RT-PCR. The median age of the series was 31 years (18-49) and disease status at BMT was: chronic phase: 11, accelerated phase: 3 and blast crisis: 1 patient. Of the 15 patients, 9 are alive and in complete remission (CR), 4 have died in CR and 2 are alive but suffered relapse at + 19 and +26 months post-BMT. The median follow-up is 81 months (13,7-168). Rearrangement of the BCR gene was performed by Southern-blot using P32-labeled transprobe-1. PCR analysis of chimerism was assessed using primers for the following VNTR loci: D1S80, D1S111, 33.1, APO-B, YNZ-22, lambdag3 and DXS52. Seventy-nine samples were analyzed (median per patient 5 (range 2-9)). Thirteen patients showed complete chimerism and lacked BCR rearrangement over time by Southern-blot. The 2 patients who relapsed showed mixed chimera status from +9 and +5 months respectively until the end of the study. Persistent BCR rearrangement was observed in these 2 patients from +12 and +11 months respectively. Our data suggest that mixed chimerism may predict hematologic or cytogenetic relapse by several months in those patients who are persistently PCR-positive post-BMT.
Adult↗
Two novel mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene in X-linked retinitis pigmentosa (RP3). Mutations in brief no. 172. Online.
Recently a new gene called RPGR (retinitis pigmentosa GTPase regulator) was isolated in Xp21.1 and found to be mutated in patients with RP3 type X-linked retinitis pigmentosa. Two new mutations, the first a single base pair deletion and the other a two base pairs deletion, have been found in one Spanish and one Italian family.
Carrier Proteins↗
[Thalassemia intermedia caused by interaction of IVS-1 1(G--A) mutation in the beta-globin gene and heterozygotic triplication in the alpha-globin gene].
Thalassemia intermedia is a clinical entity characterized by moderate, non-transfusional anemia and hepatosplenomegaly. This phenotype can result from different genetic combinations and is sometimes present in patients with only one parent showing the thalasemia minor phenotype. We report here a family with seven members with the thalassemia beta trait, four of them with thalasemia minor and the other three with thalassemia intermedia. The genetic study of patients with thalassemia intermedia revealed the presence of the mutation IVS-1 1(G-->A) in the beta-globin gene and the heterozygous triplication of the alpha-globin gene, an uncommon association in Spain. The interaction of a mutation in the beta-globin gene with triplication of the alpha-globin gene should be considered in the diagnosis and genetic counselling in those patients with thalassemia intermedia and one normal parent.
Adolescent↗
Differences in phenotypic expression of a new BRCA1 mutation in identical twins.
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Adult↗
A new locus for autosomal recessive retinitis pigmentosa (RP19) maps to 1p13-1p21.
Autosomal recessive retinitis pigmentosa (arRP) is characterized by considerable allelic and nonallelic heterogeneity. Mutations have been described in the rhodopsin gene (RHO), the genes encoding the alpha and beta subunits of rod phosphodiesterase (PDEA and PDEB), and the gene encoding the alpha subunit of the cGMP-gated channel (CNCG). In addition, linkage studies in single extended pedigrees have defined two new arRP loci, at 1q and 6p. To identify the disease gene in a Spanish consanguineous arRP family, a linkage analysis was undertaken. After testing 102 polymorphic markers, a significant positive lod score (Zmax = 3.64 at theta = 0) was obtained with marker D1S188 at 1p13-p21, the same region where the Stargardt and fundus flavimaculatus (FFM) loci were previously defined. Exhaustive ophthalmologic examination of the patients clearly distinguished the disease from the Stargardt and FFM phenotypes and revealed an atypical form of arRP with choroidal atrophy as a distinctive feature.
Aged↗
A five-basepair deletion (7118 delTTTTA) identified within neurofibromatosis (NF1) exon 39.
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Base Composition↗
Identification of a novel somatic mutation in the RET proto-oncogene in a patient with sporadic medullary thyroid carcinoma.
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Carcinoma, Medullary↗
Putative association of a mutant ROM1 allele with retinitis pigmentosa.
Retinitis pigmentosa (RP) is a clinically and genetically heterogeneous form of retinal degeneration. Several genes and loci have been shown to be involved in the disease, although each of them only accounts for a few cases. Mutations in the gene encoding ROM1, a rod-specific protein, have been putatively associated with several forms of RP. Here we describe a double-mutant allele of this gene, P60T and T108M, present in two affected sibs and also in two healthy members of a Spanish RP family. The same double-mutant allele was previously considered to be responsible for autosomal dominant RP in one family. We now report data that question the potential pathogenicity of these two ROM1 mutations.
Adolescent↗
Molecular diagnosis of von Hippel-Lindau disease in a kindred with a predominance of familial phaeochromocytoma.
OBJECTIVE: To study the presence of germline mutations in the von Hippel-Lindau gene (vhl) in a kindred with a predominance of familial phaeochromocytoma in order to confirm the diagnosis of von Hippel-Lindau disease (VHLD) as well as to identify asymptomatic members. DESIGN: DNA extracted from peripheral blood was amplified by the polymerase chain reaction using oligonucleotide primers corresponding to exon 3 of the vhl gene. Specific mutations in codon 238 were screened by restriction endonuclease digestion of PCR products with Msp I. The results were confirmed by DNA sequence analysis. PATIENTS: Two generations of a family consisting of 15 individuals were studied. RESULTS: A germline missense point mutation at codon 238 of the vhl gene (CGG-->TGG; Arg-->Trp) was detected in all patients with phaeochromocytoma and in only one of the asymptomatic family members. CONCLUSION: Mutational analysis of the vhl gene in patients with familial phaeochromocytoma may permit specific diagnosis of von Hippel-Lindau disease, and is a good method for the identification of asymptomatic individuals at risk of von Hippel-Lindau disease.
Adolescent↗
Somatic instability of the myotonic dystrophy (CTG)n repeat during human fetal development.
Myotonic dystrophy is characterised by the striking level of somatic heterogeneity seen between and within tissues of the same patient, which probably accounts for a significant proportion of the pleiotropy associated with this disorder. The congenital form of the disease is associated with the largest (CTG)n repeat expansions. We have investigated the timing of instability of myotonic dystrophy (CTG)n repeats in a series of congenitally affected fetuses and neonates. We find that during the first trimester the repeat is apparently stable and that instability only becomes detectable during the second and third trimesters. In our series repeat instability is apparent only after 13 weeks gestational age and before 16 weeks. The appearance of heterogeneity shows some tissue specificity, with heart most commonly having the largest expansion. The degree of heterogeneity is not correlated with initial expansion size as gauged by chorionic villus and blood (CTG)n repeat sizes.
Embryonic and Fetal Development↗
Primary neuroendocrine carcinoma of the skin expresses tyrosinase mRNA: detection by a specific nested PCR technique.
BACKGROUND: Tyrosinase transcripts have been identified in a wide range of normal organs and neoplasms such as cutaneous nevi, breast carcinomas, liposarcomas and schwannomas. The cells responsible for these positive results have not been accurately identified yet, but they might correspond to either fully differentiated melanocytes, melanocytic precursors or cells bearing potential for melanocytic differentiation. OBJECTIVE: To assess the expression of tyrosinase mRNA in surgical resection specimens and peripheral blood samples from 2 patients with primary neuroendocrine carcinomas of the skin (PNCS). METHODS: The expression of tyrosinase mRNA transcripts was tested by means of a reverse-transcriptase and nested PCR technique, using specific primers, in tissue samples from surgical specimens and heparinized blood samples from 2 patients with PNCS. RESULTS: The results of the test were positive in the 2 specimens of PCNS but negative in blood samples. CONCLUSION: Our findings provide further support for the hypothesis that PNCS originates from a pluripotent stem cell capable of neuroendocrine cell differentiation, keratin production, and, as reported herein, tyrosinase mRNA expression. It remains to be seen whether this technique can also be applied to patients with PNCS, as an adjunct to staging and treatment planning.
Aged↗
Cramps and minimal EMG abnormalities as preclinical manifestations of spinal muscular atrophy patients with homozygous deletions of the SMN gene.
The characterization of deletions in the SMN gene provides a helpful tool to confirm the diagnosis of spinal muscular atrophy (SMA). However, there may be homozygous deletions of the SMN gene in some unaffected siblings of SMA type II and III patients. We present two SMA families with affected siblings demonstrating a homozygous deletion of the SMN gene with extremely different phenotypes. We propose a preclinical category of an SMA patient with homozygous deletion of the SMN gene: those with minimal expression of the disease including cramps and EMG abnormalities that may develop the complete SMA phenotype in the future.
Adolescent↗
Inhibition of urokinase-type plasminogen activator (uPA) abrogates myogenesis in vitro.
Urokinase-type plasminogen activator (uPA) is one of the components of blood's fibrinolytic cascade. uPA acts as a broad spectrum proteolytic enzyme involved in different physio-pathological processes including cellular fibrinolysis, adhesion, migration, invasion and remodeling. Here, we present evidence that uPA participates in myogenesis, a process which requires drastic cell membrane reorganization, leading to the plurinucleated myotube from the progenitor myoblast. We have dissected the expression of uPA throughout the different myogenic compartments and found an increase in uPA enzymatic activity associated with myotube formation in C2C12 myoblast cells, with uPA mRNA increasing prior the onset of fusion and differentiation. When both fusion and differentiation were blocked by specific inhibitors (DMSO, cytochalasin B) the levels of uPA were strongly downregulated. This process was reversible and specific: the removal of the inhibitors immediately restored the levels of uPA mRNA while the specific inhibition of uPA enzymatic activity by an anti-uPA antibody resulted in a 50% reduction of the extent of fusion and in the abrogation of muscle-specific gene products, such as alpha-actin and MyoD. Moreover, the conversion of fibroblasts to muscle-like cells upon acquisition of MyoD resulted in a dramatic increase of uPA mRNA, which was partially due to transcriptional activation of the uPA gene. These results indicate that the increase in uPA expression prior to fusion and differentiation occurs via a MyoD-mediated mechanism whereas the normal MyoD expression requires the plasminogen activation-dependent activity of this protease. Therefore, these studies extend the sphere of influence of myogenic factors to fibrinolysis, an intrinsic component of the hematological system. Taken together, one mechanism used by the myoblast cell to become a differentiated myotube, involving the inductive extracellular proteolysis of urokinase, is proposed.
Actins↗
Prediction of myotonic dystrophy clinical severity based on the number of intragenic [CTG]n trinucleotide repeats.
We carried out a genotype-phenotype correlation study, based on clinical findings in 465 patients with myotonic dystrophy (DM), in order to assess [CTG] repeat number as a predictive test of disease severity. Our analysis showed that the DM subtypes defined by strict clinical criteria fall into three different classes with a log-normal distribution. This distribution is useful in predicting the probability of specific DM phenotypes based on triplet [CTG] number. This study demonstrates that measurement of triplet expansions in patients' lymphocyte DNA is highly valuable and accurate for prognostic assessment.
Disease Progression↗
[Identification of Arg-135-Leu mutation in the rhodopsin gene in a family with autosomal dominant retinitis pigmentosa].
Mutations in the rhodopsin gene have been sought in a family with autosomal dominant retinitis pigmentosa. Screening for mutations in the rhodopsin gene was carried out by polimerase chain reaction and denaturant gradient gel electrophoresis. Direct DNA sequencing was performed for the characterization of punctual mutations. A base substitution in the exon 2 of the rhodopsin gene was detected. Direct DNA sequencing revealed a CGC to CTG change in codon 135, that substitutes arginine for leucine residue in rhodopsin. The mutation segregates with the disease phenotype in the family. The mutation Arg-135-Leu causes the retinitis pigmentosa phenotype in the family, where the disease is inherited following an autosomal dominant pattern.
Adult↗
Deletion analysis of the simple tandem repeat loci physically linked to the spinal muscular atrophy locus.
Multicopy dinucleotide repeats have been characterized in the spinal muscular atrophy (SMA) region on chromosome 5q13, which reveal deletions in some SMA patients. 119 Italian and Spanish SMA families have been analysed using the C272 and C212 markers. Seventy percent of these families were informative. We found 9.4% de novo deletions in SMA I and 1.5% in SMA II families. A single inherited deletion segregating in a Spanish pedigree was detected in three affected brothers. A SMA II patient showed deletion only of C272. The data presented in this study are relevant to the molecular diagnosis of SMA families in Italy and Spain and provide additional insights toward the understanding of the molecular pathology of SMA.
Alleles↗