Kinetic path of genes undergoing selection.

As natural populations approach genetic equilibrium, the various genes in the population are capable of assuming intermediate distributions that might not be anticipated from either the rate of the process or the final distribution of the genes. Since it is possible that many populations have not reached genetic equilibrium, the distribution of genes in natural populations may be a reflection of the kinetic path by which the genes approach equilibrium. Attention to kinetic path provides an explanation for an apparent discrepancy in recent studies of selection in man.

Newborn screening in North Carolina: the evolution of policy and practice.

Newborn screening policies in North Carolina are due to the efforts of skilled and knowledgeable state officials, clinicians, and scientists who are able to develop effective newborn screening procedures. A newborn screening that was developed in North Carolina is the first automated method for diagnosing phenylketonuria. This process was later adopted in many other states. The use of tandem mass spectrometry in newborn screening was also pioneered in North Carolina, and it is being used in an increasing number of states. Newborn screening is more than testing, however; follow-up and specialized care are essential. State-level policies should recognize the multiple links necessary to make newborn screening effective and efficient.

Red cell NADP+ and NADPH in glucose-6-phosphate dehydrogenase deficiency.

Extraction in the presence of sodium hydroxide and cysteine allows estimates of NADPH and total NADP in human red cells without the erroneously high values of NADP+ obtained with earlier methods. An application of this technique to G6PD-deficient cells reveals that most of the nucleotide is in the oxidized form. In contrast, normal red cells have nearly all of the nucleotide in the reudced form. In addition to providing information concerning the intracellular regulation of the hexose monophosphate shunt, these findings support the concept that G6PD deficiency is a product-deficiency disorder.

Histogenetic and morphological in vivo and in vitro data concerning androgen-estrogen-induced scent gland tumor in the Syrian hamster.

The scent gland tumor of the Syrian hamster is induced by exogenous androgen and estrogen. Microscopic nodules are induced normally in old males by endogenous androgen. The histogenesis of the scent gland tumor is complex and not completely understood. In this study microscopic preneoplastic nodules and macroscopic tumors were studied by light and electron microscopy, and the macroscopic tumors were grown in tissue culture on collagen-coated coverslips and on sponge foam matrices by the organ culture method. The cultures were fed with an unfiltered fetal calf serum-bovine serum ultrafiltrate medium, which contained endogenous androgen-estrogen, 110-100 pg and could maintain growth without additional androgen-estrogen. Exogenous androgen-estrogen was also added to some cultures. Scent gland tumors grown in organ culture contained cells of two shapes, spindle and ovoid arranged in cords. Cultures on coverslips showed radiating outgrowths of spindle cells suggesting either mesenchymal or Schwann cells. By electron microscopy, both in vivo and in vitro preneoplastic and tumor samples contained cells with segments of basal lamina, micropinocytotic vesicles, and junctional complexes. These features were similar to those of poorly differentiated experimental malignant rat schwannomas maintained in similar in vitro systems. Tumors grown in vivo and in vitro were associated with collagen fibrils with a periodicity ranging from 400 to 1075 A. The evidence reported in this paper suggests that one component of the scent gland tumor is an androgen-estrogen-induced poorly differentiated schwannoma.

Tetrasomy 9p: tissue-limited idic(9p) in a child with mild manifestations and a normal CVS result. Report and review.

Supernumerary isochromosomes resulting in autosomal tetrasomy are rare and have been described only for 12p, 18p, and 9p. Nineteen previous cases of tetrasomy 9p have been reported, and in 6 cases, tissue-specific mosaicism was implied with the i(9p) cell line present exclusively or predominantly in blood. We report on an infant who had apparently normal chromosomes (46,XY) on CVS. He was referred for genetic evaluation because of mild developmental delay and minor anomalies. In 75% of blood cells he had an extra isodicentric 9p chromosome (pter-->q12-->pter). The interpretation of tetrasomy 9p was confirmed by elevated GALT activity. No tetrasomy 9p cells were seen in 100 skin fibroblasts. This case demonstrates the tissue specific mosaicism in tetrasomy 9p which rendered the anomaly undetectable by CVS. It also demonstrates the mild end of the clinical spectrum associated with tetrasomy 9p.

Genetic screening of donors for artificial insemination.

A routine has been established for genetic screening of donors in an artificial insemination and frozen sperm bank program. This report is a summary and analysis of the information obtained on the first 168 donor applicants and 89 recipients who were genetically screened. The specific forms for screening, family information obtained, characteristics of the donor and recipient groups, and guidelines for acceptance or rejection of donors are discussed. The donor and recipient often failed to perceive that the disorders in the family were genetic. The simple question of whether or not there were genetic or hereditary problems in the family was ineffective, even when the donor or recipient had formal medical training.

Erythrocytic uridine diphosphate galactose in galactosaemia.

An earlier claim of a deficiency of uridine diphosphate galactose in erythrocytes of galactosaemia patients was not confirmed. Enzymic techniques similar to those of the earlier investigators were used to determine not only the concentration of uridine diphosphate galactose but also the ratio of this concentration to the sum of the uridine sugar diphosphates (uridine diphosphate galactose and uridine diphosphate glucose). The values in erythrocytes of galactosaemic subjects were similar to those of non-galactosaemic children on a galactose-restricted diet and to those of normal adults. These results cast doubt on the claim of a major deficiency of uridine diphosphate galactose in galactosaemia and on the need for treating galactosaemic children with uridine.

Measurements of uridine diphosphate glucose and uridine diphosphate galactose--an appraisal.

The recent disproof of a major deficiency of uridine diphosphate galactose in galactosemia should not lead investigators to assume either that enzymatic methods are unreliable for uridine sugar assays or that a defect in galactosylation in galactosemia has been excluded.