Distribution of the F374 allele of the SLC45A2 (MATP) gene and founder-haplotype analysis.

The membrane-associated transporter protein (MATP) plays an important role in melanin synthesis. The L374F mutation in the SLC45A2 gene encoding MATP has been suggested to be associated with skin colour in major human populations. In this study more detailed distribution of the F374 allele was investigated in 1649 unrelated subjects from 13 Eurasian populations and one African population. The highest allele frequency was observed in Germans (0.965); French and Italians showed somewhat lower frequencies; and Turks had an intermediate value (0.615). Indians and Bangladeshis from South Asia were characterized by low frequencies (0.147 and 0.059, respectively). We also found the F374 allele in some East and Southeast Asian populations, and explained this by admixture. Haplotype analysis revealed that the haplotype diversity was much lower in Germans than in Japanese, and suggest that the L374F mutation occurred only once in the ancestry of Caucasians. The large differences in distribution of the F374 allele and its haplotypes suggest that this allele may be an important factor in hypopigmentation in Caucasian populations.

A new mutation of the noggin gene in a French Fibrodysplasia ossificans progressiva (FOP) family.

A new mutation of the Noggin gene in a French Fybrodysplasia ossificans progressiva (FOP) family: Fibrodysplasia ossificans progressiva (FOP) is a very rare disease characterized by congenital malformation of the great toes and progressive heterotopic ossification of the muscles. We previously located a FOP gene in the 17q21-22 region and described several mutations of the noggin (NOG) gene (located in 17q22) in four FOP patients, including the G91C mutation which is transmitted dominantly in a Spanish FOP family. We describe in the present study a new mutation of the NOG gene in a French FOP family. This new mutation is a guanine to adenine change at nucleotide 283 (283G --> A) of the NOG gene, and is transmitted in the family (in the heterozygote form) by the affected mother to her two affected children. At the peptide level this mutation (A95T) substitutes an Alanine residue by a Threonine at position 95 of the Noggin protein. The Alanine mutated residue is located just adjacent to the myristoylation site of the protein, where all the mutations we described until now are located.

TNF-alpha polymorphisms in multiple sclerosis: no association with -238 and -308 promoter alleles, but the microsatellite allele a11 is associated with the disease in French patients.

Tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine, is believed to play an important role in multiple sclerosis (MS) pathogenesis. The objective of this study was to determine whether sequence variation in the TNF-alpha gene is associated with MS. Bi-allelic polymorphisms in the TNF-alpha promoter region (TNF-alpha -238 and -308) and microsatellite TNF-alpha were previously reported. We investigated these polymorphisms in 74 French patients with MS, compared with 75 controls. No significant differences regarding the TNF-alpha -238 and -308 polymorphisms were observed between MS patients and controls. Allele frequency for the a11 allele is in very significant association (P<0.0001) with MS, due in part to the association of the a11 allele with the HLA-DRB1*15 allele in patients.

The use of nested RT-PCR of prostate-specific membrane antigen in blood cells: implications for the detection of haematogenous neoplastic cells in patients with prostate adenocarcinoma.

The aim of this study was to determine the presence of haematogenous neoplastic cells in patients with prostate cancer. Circulating prostate cells can be detected in cancer patients by using a nested-reverse transcriptase-polymerase chain reaction assay (RT-PCR), for prostate-specific membrane (PSM) antigen mRNA. This sensitive nested RT-PCR assay may play a crucial role in the administration of adjuvant therapy of patients with prostate adenocarcinoma.

G542X as a probable Phoenician cystic fibrosis mutation.

When analyzed by origin, the frequency of the G542X cystic fibrosis (CF) mutation (the second most common CF mutation in Europe after DF508) varies between population groups in Europe. We show here that the frequency of G542X varies among different towns or regions of origin, being lower in northeastern Europeans than in southwestern Europeans. The G542X mutation mapping that we have defined by a multiple regression of G542X frequencies covers 28 countries (53 geographic points) and is based on data from 50 laboratories. The more elevated values of G542X frequency correspond to ancient sites of occupation by occidental Phoenicians.

Identification of common cystic fibrosis mutations in African-Americans with cystic fibrosis increases the detection rate to 75%.

Cystic fibrosis (CF)--an autosomal recessive disorder caused by mutations in CF transmembrane conductance regulator (CFTR) and characterized by abnormal chloride conduction across epithelial membranes, leading to chronic lung and exocrine pancreatic disease--is less common in African-Americans than in Caucasians. No large-scale studies of mutation identification and screening in African-American CF patients have been reported, to date. In this study, the entire coding and flanking intronic sequence of the CFTR gene was analyzed by denaturing gradient-gel electrophoresis and sequencing in an index group of 82 African-American CF chromosomes to identify mutations. One novel mutation, 3120+1G-->A, occurred with a frequency of 12.3% and was also detected in a native African patient. To establish frequencies, an additional group of 66 African-American CF chromosomes were screened for mutations identified in two or more African-American patients. Screening for 16 "common Caucasian" mutations identified 52% of CF alleles in African-Americans, while screening for 8 "common African" mutations accounted for an additional 23%. The combined detection rate of 75% was comparable to the sensitivity of mutation analysis in Caucasian CF patients. These results indicate that African-Americans have their own set of "common" CF mutations that originate from the native African population. Inclusion of these "common" mutations substantially improves CF mutation detection rates in African-Americans.

Complete map of cystic fibrosis mutation DF508 frequencies in Western Europe and correlation between mutation frequencies and incidence of disease.

The frequencies of DF508, the main cystic fibrosis mutation, vary among different populations in Western Europe; they are higher in northwestern Europeans than in southeastern populations. Our new analysis is based on results from 66 different laboratories on 17,886 cystic fibrosis chromosomes (from 70 locations and 26 countries). The correlation between DF508 frequency values and cystic fibrosis incidence is calculated in the corresponding groups.

Geographic and ethnic distributions of the more frequent cystic fibrosis mutations in Europe show that a founder effect is apparent for several mutant alleles.

Examination of the European geographic patterns of the 10 relatively most frequent cystic fibrosis mutations, other than the DF508 one, shows that a founder effect is apparent for a number of them. The most evident examples are for the W1282X mutation in Jews, with a probable Asian origin, and the G551D and R117H mutations in Celts. Geographic distributions indicate that the main focus of the 621 + 1 G-->T and DI507 mutations is probably located in Wales. Also, the R1162X mutation probably originates from a circumscribed north Italian region. The N1303K mutation has a wide range in Europe with a clear preponderance in southern countries. Even the relatively common G542X and 1717.1 G-->A mutations have a local preponderance in Spain and Sicily and in northern Italy, respectively. Likelihood estimates for recurrent mutation and identity by descent strongly support the hypothesis of recurrence for the (mainly German) mutation R553X.

Prenatal diagnosis for the unstable CTG repeat sequence in myotonic dystrophy: a retrospective study in a French family.

The results of DNA analysis for the unstable CTG repeat are reported in a french family of myotonic dystrophy. This retrospective study confirms results obtained previously with a linked DNA marker, using the CTG repeat DNA sequence in the same family. The demonstrated possibility of predicting phenotype as well as genotype in prenatal diagnosis is important for such a disorder, were subjects may be severely affected.

A multiple primer pairs polymerase chain reaction for the detection of human genital papillomavirus types.

We describe a polymerase chain reaction (PCR) based on the simultaneous detection of multiple strains of papillomavirus in a single reaction tube. This PCR method was specific and sensitive. We have validated this multiplex procedure on a collection of typed cervical biopsies specimens, and applied it to the detection of viruses in some clinical samples.

A more detailed map of the cystic fibrosis mutation DF508 frequencies in Europe.

When analyzed by origin, the frequency of the DF508 mutation (the main cystic fibrosis mutation) varies between population groups. We show here that the frequency of the DF508 mutation varies among different populations, being higher in northwest Europeans than in southeast European populations. The map we have constructed covers 25 countries; isofrequency curves were calculated using an original method.

A transthyretin variant (alanine 71) associated with familial amyloidotic polyneuropathy in a French family.

A transthyretin (TTR) mutation is described in a 44 year old French woman from Caen who presented at the age of 40 with neuropathy in all four extremities, diarrhoea, and orthostatic hypotension. Her father died with a similar syndrome including vitreous opacities. A nerve biopsy from the proband showed amyloid deposits which stained with anti-transthyretin. Direct genomic DNA sequencing of TTR exon 3 showed both thymine and cytosine in the position corresponding to the second base of codon 71. This codes for a variant alanine (GCG) as well as the normal valine (GTG), indicating that the proband is heterozygous for the substitution. Since this substitution does not result in the creation or abolition of a restriction endonuclease recognition site, a new technique (PCR-IMRA) was used to create an RFLP. Using a 24 bp nucleotide mutagenesis primer in the PCR reaction, a new NspBII site is created on amplification of the variant allele. With this method a 170 bp TTR exon 3 PCR product was generated for both the normal and the variant allele. On digestion of the PCR product with NspBII, DNA from a heterozygous subject showed both the 170 bp undigested product from the normal allele and a 146 bp digestion product from the variant allele. By PCR-IMRA, two of five children of the proband were positive for the variant allele. This non-radioactive technique gives a rapid method for testing subjects at risk for this mutation.

Prenatal diagnosis of hereditary amyloidosis in a Portuguese family living in France.

Portuguese type amyloidosis is an autosomal dominant condition caused by a mutation in the transthyretin gene. This mutation can be detected directly by the presence of a restriction site for NsiI. We report here our first prenatal diagnosis for this condition performed by chorionic villus sampling, polymerase chain reaction, and restriction enzyme digestion.