A. Donald Merritt

A syndrome of bizarre vertebral anomalies

Four of seven siblings, the offspring of a consanguineous marriage, have been affected bya newly recognized syndrome. The clinical pattern is characteristic and consists of markedly shortened posterior thorax and neck, increased anteroposterior chest diameter, protuberant abdomen, and bizarre roentgenograms of the chest and spine. The mode of inheritance appears to be autosomal recessive.

Evidence for post-transcriptional modification of human salivary amylase (Amy1) isozymes

Human parotid salivary amylase (Amy1) isozymes may be separated into two families: (1) one of higher molecular weight and slower electrophoretic mobility, odds, and (2) the other of lower molecular weight and faster electrophoretic mobility, evens. An enzyme has been detected in whole saliva, and also partially purified from human oral bacterial flora, which converts the isoamylases from odds to evens. No similar modifying activity was detected in parotid saliva or submandibular and sublingual salivas. A model is presented which explains the multiple isozymes of salivary amylase by post-transcriptional modification of a single gene product.

Immunological relationships and post-translational modifications of human salivary amylase (Amy1) and pancreatic amylase (Amy2) isozymes

Electrophoretic phenotypes of human salivary amylase (Amy1) and pancreatic amylase (Amy2) consist of complex isozyme patterns which may result from post-translational modifications of the primary products of the amylase loci. Biochemical separation of the two molecular weight families of salivary amylase and development of a new electrophoretic system have allowed the identification of complete isozyme patterns corresponding to variant alleles in Amy1 and Amy2 heterozygotes. Further, immunological studies show no nonidentities among salivary isozymes and among pancreatic isozymes, which is to be expected if each series is derived from a single gene product. Both results support the hypothesis that the primary products of the amylase loci undergo post-translational modifications. Salivary and pancreatic amylase appear to be immunologically identical.

Immunological and chemical comparison of heterogeneous basic glycoproteins in human parotid saliva

Abstract Closely related glycoproteins have been isolated from individual samples of parotid saliva. The heterogeneous nature of these glycoproteins has been established by chromatographic, electrophoretic, and immunologic studies. Substantial differences in specific carbohydrate moieties and overall charge densities are also evident. These results are discussed in terms of previous salivary glycoprotein reports. Family studies to define heritable facets of this polymorphism are now indicated.

The Human α-Amylases

About 12 years ago in 1965, Kamaryt and Laxova105,106 suggested a genetic basis for the inheritance of salivary and pancreatic amylase in human serum. Although results from these and other early isozyme studies of α-amylase differed when obtained from saliva, pancreas, serum, and urine,157 it was not until extensive studies performed after 1969 that the multiple isozymes demonstrable in various tissue fluids and extracts were shown to be the heterogeneous products of two loci, Amy 1 (salivary-type amylase) and Amy 2 (pancreatic-type amylase).

GENETIC AND POST-TRANSLATIONAL MECHANISMS DETERMINING HUMAN AMYLASE ISOZYME HETEROGENEITY

ABSTRACT . Human α-amylase expressions in tissue and secretion sources yield complex phenotypes when subjected to discontinuous polyacrylamide sheet electrophoresis. Two loci, Amy j active in the salivary glands and Amy 2 active in the pancreas, produce different electrophoretic phenotypes. Genetic studies show Mendelian segregation of the multiple alleles at each locus; however, studies involving double heterozygotes show that the two loci are closely linked with the variant alleles being either in coupling or repulsion. Population data showing the distributions of the Amy 1 and Amy 2 phenotypes are also presented. In addition to genetic studies, biochemical separation of amylase isozymes and a modified electrophoretic system have allowed further resolution of amylase phenotypes. Data are presented demonstrating that the complex isozyme patterns are the result of post-translational modifications: glycosidation and deamidation, both occurring in the expression of salivary phenotypes and deamidation in pancreatic phenotypes. Salivary and pancreatic amylases were also compared in immunologic analyses employing double diffusion and found to be immunologically indistinguishable. We have combined this observation with the conclusion that the two loci are closely linked and advance the hypothesis that the loci are the result of a duplication.

The tissue origins of serum and urinary α-amylase

Abstract Past claims for α-amylase produced in the liver have been based on the lack of inhibition of enzyme activity by antiserum produced against salivary amylase, quantitated with a starch-iodine assay. This study represents a reevaluation of amylase inhibition in human tissues and fluids using purified antibodies to salivary amylase. Amylase activity was assessed by monitoring both the disappearance of starch (amyloclastic assay) and the production of reducing sugar (saccharogenic assay). Essentially complete inhibition of enzyme activity assessed by both methods was achieved in those tissues and fluids not containing albumin. The presence of albumin resulted in false activity in the starch-iodine assay and consequently lower inhibitions of activity by antisalivary amylase antibodies than could be obtained in the saccharogenic assay. In addition, saccharogenic activity not inhibited by antisalivary amylase antibodies in liver extracts was found to be due to α-1,4-glucosidase. These results suggest that no immunologically unique amylase is produced in the liver, a finding supported by electrophoretic studies.

POPULATION GENETICS AND HEMOPHILIA‐IMPLICATIONS OF MUTATION AND CARRIER RECOGNITION

The flow of genes in human populations is controlled and varied by many forces. Among the forces are mutation, selection, relative fitness, gene segregation and linkage, mating habits, family size, variability in the birth rate, genetic drift, founder effects, socioeconomic factors, and environmental interactions. Of more relevance to this symposium are the frequency of hemophilia, heterogeneity among hemophiliacs, and heterozygote detection. It is also appropriate to consider the possible mechanisms for allowing relatively normal biologic function in hemophiliacs while minimizing the various personal, emotional, and socioeconomic “costs,” and the societal effects, not the least of which is the drain on the nation’s blood resource.