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W S Oetting

Publications and source records attributed to W S Oetting.

At least 37 records · Page 2Linked to original sources
PubMed1995

Linkage analysis with multiplexed short tandem repeat polymorphisms using infrared fluorescence and M13 tailed primers.

The use of short tandem repeat polymorphisms (STRPs) as marker loci for linkage analysis is becoming increasingly important due to their large numbers in the human genome and their high degree of polymorphism. Fluorescence-based detection of the STRP pattern with an automated DNA sequencer has improved the efficiency of this technique by eliminating the need for radioactivity and producing a digitized autoradiogram-like image that can be used for computer analysis. In an effort to simplify the procedure and to reduce the cost of fluorescence STRP analysis, we have developed a technique known as multiplexing STRPs with tailed primers (MSTP) using primers that have a 19-bp extension, identical to the sequence of an M13 sequencing primer, on the 5' end of the forward primer in conjunction with multiplexing several primer pairs in a single polymerase chain reaction (PCR) amplification. The banding pattern is detected with the addition of the M13 primer-dye conjugate as the sole primer conjugated to the fluorescent dye, eliminating the need for direct conjugation of the infrared fluorescent dye to the STRP primers. The use of MSTP for linkage analysis greatly reduces the number of PCR reactions. Up to five primer pairs can be multiplexed together in the same reaction. At present, a set of 148 STRP markers spaced at an average genetic distance of 28 cM throughout the autosomal genome can be analyzed in 37 sets of multiplexed amplification reactions. We have automated the analysis of these patterns for linkage using software that both detects the STRP banding pattern and determines their sizes. This information can then be exported in a user-defined format from a database manager for linkage analysis.

Chromosome Mapping↗
PubMed1995

A gene causing Hermansky-Pudlak syndrome in a Puerto Rican population maps to chromosome 10q2.

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder that affects pigment production and platelet function and causes the deposition of a ceroid-like material in various tissues. Variability in the phenotype and the presence of several potential mouse models suggest that HPS may be a heterogeneous disorder. In order to identify a gene responsible for HPS, we collected blood samples from a relatively homogeneous population in Puerto Rico where the HPS carrier frequency is estimated to be 1 in 21. Analysis of pooled DNA samples allowed us to rapidly screen the genome for candidate loci, and significant evidence for linkage was detected for a marker on chromosome 10q. This region of the human genome is conserved syntenically with the region on mouse chromosome 19 where two possible mouse models for HPS, pale ear and ruby eye, are located. This linkage result was verified with additional markers, and a maximum LOD score of 5.07 at theta = .001 was calculated for marker D10S198. Haplotype analysis places the HPS gene in a region of approximately 14 cM that contains the markers D10S198 and D10S1239.

Albinism, Oculocutaneous↗
PubMed1994

Analysis of tyrosinase gene mutations using direct automated infrared fluorescence DNA sequencing of amplified exons.

The ability to correctly diagnose the molecular cause of genetic diseases is becoming increasingly important in medicine. This requires an efficient method for the analysis of the DNA sequence of specific genes and the detection of mutations in affected individuals. We report a method to determine the mutations responsible for tyrosinase related albinism (OCA1) using a combination of polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP) analysis and direct DNA cycle sequencing using fluorescently labeled oligonucleotides and an automated DNA sequencer based on infrared fluorescence technology. This method allows DNA from several individuals to be sequenced quickly and simultaneously so that the specific location of each mutation and the carrier status of family members can be determined.

Albinism, Oculocutaneous↗
PubMed1994

Molecular basis of oculocutaneous albinism.

Oculocutaneous albinism (OCA) is a complex group of genetic disorders that have historically been defined by clinical and biochemical methods. Recent advances in the molecular biology of pigmentation have greatly increased our understanding of the complexity of this group of disorders. To date, two different types of OCA (OCA1 and OCA2) have been mapped to specific chromosomal regions. Mutations have been found in the tyrosinase locus associated with OCA1 and the human homologue to the murine pink-eyed dilution locus associated with OCA2. Analysis of these genes and their mutations will allow us to better define and categorize the different types of albinism. Further, the analysis of these genes and their mutations will provide information on the role of these gene products in melanin biosynthesis and the effect specific mutations have on the pathogenesis of albinism.

Albinism, Oculocutaneous↗
PubMed1994

Analysis of tyrosinase mutations associated with tyrosinase-related oculocutaneous albinism (OCA1).

Mutations of the tyrosinase gene associated with a partial or complete loss of enzymatic activity are responsible for tyrosinase related oculocutaneous albinism (OCA1). A large number of mutations have been identified and their analysis has provided insight into the biology of tyrosinase and the pathogenesis of these different mutations. Missense mutations produce their effect on the activity of an enzyme by altering an amino acid at a specific site. The location of these mutations in the peptide can be used to indicate potential domains important for enzymatic activity. Missense mutations of the tyrosinase polypeptide cluster in four regions, suggesting that these are important functional domains. Two of the potential domains involve the copper binding sites while the others are likely involved in substrate binding. More critical analysis of the copper binding domain of tyrosinase can be gained by analyzing the structure of hemocyanin, a copper-binding protein with a high degree of homology to tyrosinase in the copper binding region. This analysis indicates a single catalytic site in tyrosinase for all enzymatic activities.

Albinism, Oculocutaneous↗
PubMed1994

Albinism and the associated ocular defects.

Several types of hypopigmentation in humans are called albinism. The phenotype for different types of albinism varies according to the amount of pigment in the hale, skin and iris, the reduction in visual acuity and the degree of nystagmus and strabismus. Cutaneous and ocular melanin pigment can range from complete absence throughout the lifetime of the individual to the development of nearly normal levels, including the ability to tan. Visual acuity ranges from 20/40 to 20/400, and visual development in an affected infant is slower than normal. Foveal hypoplasia and altered routing of the optic nerves are found in all types of albinism and are the most constant feature of this condition. The demonstration of optic track misrouting by visual evoked potential studies provides the critical diagnostic procedure for questionable cases of albinism, and this is the single definitive diagnostic test to confirm a diagnosis of albinism.

Albinism, Ocular↗
PubMed1993

Molecular basis of type I (tyrosinase-related) oculocutaneous albinism: mutations and polymorphisms of the human tyrosinase gene.

Type I (tyrosinase related) oculocutaneous albinism (OCA) results from mutations of the tyrosinase gene on chromosome 11q that lead to reduced or absent melanin pigment synthesis. The phenotype of Type I OCA is broad, ranging from a total lack to only a moderate reduction of melanin, and the phenotypic variation is associated with different mutant alleles at the tyrosinase locus. A total of 36 mutations have been identified in Type I OCA including 24 missense, 4 nonsense, and 8 frameshift mutations. The majority of affected individuals have been compound heterozygotes with different maternal and paternal alleles. Six polymorphic sites for haplotype analysis have been identified in the tyrosinase gene including 2 in the promoter region, 2 in the coding region associated with alternative amino acids in the protein, and 2 RFLPs in the first intron.

Albinism, Oculocutaneous↗
PubMed1993

Evolution of the tyrosinase related gene (TYRL) in primates.

Tyrosinase is the major enzyme responsible for the formation of melanin pigment and is found throughout the animal kingdom. In humans, the tyrosinase gene (TYR) maps to the long arm of chromosome 11 at band q14-->q21, while a tyrosinase related gene (TYRL) maps to the short arm of chromosome 11 at p11.2-->cen. We and others have found that the TYRL locus contains sequences that are similar to exons IV and V of the authentic tyrosinase gene but lacks sequences of exons I, II, and III. In an attempt to understand the evolution of the human tyrosinase gene, we have analyzed TYR and TYRL in primates and have found that exons IV and V of the chimpanzee and gorilla TYR are very similar to the human, with the gorilla sequence being more similar than the chimpanzee. We have also found that the gorilla but not the chimpanzee contains a TYRL locus similar to the human TYRL locus.

Animals↗
PubMed1993

A frequent tyrosinase gene mutation associated with type I-A (tyrosinase-negative) oculocutaneous albinism in Puerto Rico.

We have determined the mutations in the tyrosinase gene from 12 unrelated Puerto Rican individuals who have type I-A (tyrosinase-negative) oculocutaneous albinism (OCA). All but one individual are of Hispanic descent. Nine individuals were homozygous for a missense mutation (G47D) in exon I at codon 47. Two individuals were heterozygous for the G47D mutation, with one having a missense mutation at codon 373 (T373K) in the homologous allele and the other having an undetermined mutation in the homologous allele. One individual with negroid features was homozygous for a nonsense mutation (W236X). The population migration between Puerto Rico and the Canary Islands is well recognized. Analysis of three individuals with OCA from the Canary Islands showed that one was a compound heterozygote for the G47D mutation and for a novel missense mutation (L216M), one was homozygous for a missense mutation (P81L), and one was heterozygous for the missense mutation P81L. The G47D and P81L missense mutations have been previously described in extended families in the United States. Haplotypes were determined using four polymorphisms linked to the tyrosinase locus. Haplotype analysis showed that the G47D mutation occurred on a single haplotype, consistent with a common founder for all individuals having this mutation. Two different haplotypes were found associated with the P81L mutation, suggesting that this may be either a recurring mutation for the tyrosinase gene or a recombination between haplotypes.

Albinism, Oculocutaneous↗
PubMed1992

Molecular analysis of type I-A (tyrosinase negative) oculocutaneous albinism.

Type I oculocutaneous albinism (OCA) is caused by the reduction in or absence of activity of tyrosinase in melanocytes in skin, hair, and the eyes, the result of mutations of the tyrosinase gene. To date, a total of 22 unique mutations in the coding region of tyrosinase have been described in the literature. In this report we present 5 additional mutations of the tyrosinase gene associated with type I-A OCA in four individuals, including 2 missense, 1 frameshift and 2 nonsense mutations, and review the relevant literature on all published mutations. Analysis of the distribution of all identified missense mutations (n = 17) shows that most cluster in three areas of the gene and involve amino acids conserved between humans and the mouse. Two clusters involve the copper A and copper B binding sites and may disrupt the metal ion-protein interaction necessary for enzyme function. The third cluster in exon I could represent a functional domain important in enzyme function such as the tyrosine or the dihydroxyphenylalanine (DOPA) binding site of the enzyme. Small deletions or insertions resulting in frameshift mutations and nonsense mutations are distributed throughout the coding region and do not appear to cluster.

Albinism, Oculocutaneous↗
PubMed1992

Molecular basis of type IA (tyrosinase negative) oculocutaneous albinism.

Type IA (Tyrosinase negative) oculocutaneous albinism (OCA) is produced by mutations of the tyrosinase gene. We have found a total of 13 different mutations associated with type IA OCA. Analysis of the distribution of the 9 missense mutations shows that most of these mutations cluster in three areas of the gene. All but one of these mutations involve amino acids that are conserved between the mouse and human. Two clusters involve the copper A and copper B binding sites, and could disrupt the metal ion-protein interaction necessary for enzyme function. The third cluster is in exon I and could represent an important functional domain of the enzyme such as the tyrosine binding site. The deletion or insertion frameshift mutations are distributed throughout the coding region and do not appear to cluster. We conclude that a diverse number of mutations are responsible for type IA OCA and many individuals are compound heterozygotes for mutations responsible for this genetic disease (Table 3).

Albinism, Oculocutaneous↗
PubMed1992

Analysis of mutations in the copper B binding region associated with type I (tyrosinase-related) oculocutaneous albinism.

Mutations of the tyrosinase gene are responsible for type I (tyrosinase-related) oculocutaneous albinism (OCA), an autosomal recessive genetic syndrome with a broad phenotypic spectrum. Mutant tyrosinase alleles can be associated with no melanin synthesis (I-A, tyrosinase-negative OCA), small to moderate amounts of melanin (I-B, yellow OCA) or unusual pigment patterns (I-TS, temperature-sensitive OCA). A total of 26 mutations of this gene have been described in type I OCA. Analysis of all known mis-sense mutations (n = 17) shows that most cluster in three areas of the coding region. Two clusters involve the copper A or copper B binding sites and may disrupt the metal ion-protein interaction necessary for enzyme function and the third cluster is located in exon I. Computer modeling of the secondary structure of the copper binding regions based on homology with the known crystal structure of hemocyanin show that they both consist of two alpha helices containing three histidine ligands that complex to a single copper atom. Mutations in the copper B binding region lie in the region between the two alpha helices that consists of a loop structure. These mutations may affect tyrosinase activity by either altering the position of the alpha helical domains and thus preventing proper copper binding to the histidine ligands, or affecting a catalytic or substrate binding site located between the two alpha helical domains.

Albinism, Oculocutaneous↗
PubMed1991

Molecular analysis of an extended family with type IA (tyrosinase-negative) oculocutaneous albinism.

We have analyzed the tyrosinase coding region of three individuals having Type IA OCA within an extended family using genomic DNA amplification and dideoxy sequencing. Two of the affected individuals are dizygotic twins. All three have a common missense mutation at codon 81 (Pro----Leu) within exon I. The twins have a second missense mutation at codon 371 (Asn----Thr) within exon III and the third individual has a second missense mutation at codon 47 (Gly----Asp) within exon I. For each of these three individuals, the loss of enzyme function is the result of two different mutations, showing that they are compound heterozygotes of two mutant tyrosinase alleles.

Albinism, Oculocutaneous↗
PubMed1991

Three different frameshift mutations of the tyrosinase gene in type IA oculocutaneous albinism.

Mutations in the gene for the pigment-producing enzyme tyrosinase are responsible for type IA (tyrosinase-negative) oculocutaneous albinism (OCA). Most reported mutations have been single base substitutions. We now report three different frameshift mutations in three unrelated individuals with type IA OCA. The first individual has a single base deletion within a series of five guanidines, resulting in a premature stop codon in exon I on one allele and a missense mutation at codon 382 in exon III on the homologous allele. The second individual is a genetic compound of two separate frameshift mutations, including both the same exon I single base deletion found in the first individual and a deletion of a thymidine-guanidine pair, within the sequence GTGTG, forming a termination codon (TAG) in exon I on the homologous allele. The third individual has a single base insertion in exon I on one allele and a missense mutation at codon 373 in exon III on the homologous allele. The two missense mutations occur within the copper Bbinding region and may interfere with either copper binding to the enzyme or oxygen binding to the copper. These five different mutations disrupt tyrosinase function and are associated with a total lack of melanin biosynthesis.

Albinism, Oculocutaneous↗