Improved detection of beta-thalassaemia carriers by a two-test method.
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Adult↗
Biomedical subjects
R J Gold
Publications and source records attributed to R J Gold.
Cystinuria and mental deficiency.
Several studies have shown that the incidence of cystinuria in mentally retarded populations is higher than it is in the general population. The present study found that a group of cystinurics did not differ significantly in their intelligence from their normal siblings or intelligence test norms. Since cystinuria is a heterogeneous disease, the findings of the present study could be reconciled with previous findings by supposing that only certain genotypes for cystinuria lead to mental retardation.
Adolescent↗
Tay-Sachs heterozygote screening: specificity and sensitivity.
Heterozygotes for the Tay-Sachs allele can be identified by plotting the heat-labile hexosaminidase activity in serum against the heat-stable activity. Quadratic discriminants can be constructed from homozygous normal and obligate heterozygous data and the probability of misclassification computed. The cost of counseling and the classification error is diminished by the use of 2 tests.
Genetic Testing↗
Loss of a homologous group of proteins in a dominantly inherited ectodermal malformation.
Hair from mice bearing the dominantly inherited Naked trait (NN) and from normal (NN) mice of the same inbred strain was separated into its major protein components by standard techniques. The relative amounts of proteins in these components were then determined by a regression method from the amino acid composition of the hair samples and of the fractions into which they had been separated. The results indicated that the amount of soluble fibril in Naked-mouse hair is decreased. Polyacrylamide-gel electrophoresis of this fraction prepared from the hair of both normal and Naked mice revealed that all protein bands present in the normal are also present in the Naked mice. However, a densitometric scan of the gels at 280 nm showed that the soluble fibril fraction from Naked-mouse hair is deficient in several proteins which, on amino acid analysis, were found to contain 31% glycine and 10% tyrosine. Gel filtration of S-carboxymethylkerateine prepared from normal and mutant hair showed that the mutant hair is deficient in a heterogeneous, low-molecular-weight fraction also rich in glycine and tyrosine. Our present data do not reveal the mechanism whereby a single gene locus modulates the production of several different proteins.
Amino Acids↗
A method for calculating the relative protein contents of the major keratin components from their amino acid composition.
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Amino Acids↗
The physicochemical properties of hair in the BIDS syndrome.
The physicochemical properties of hair from a new recessive syndrome associated with brittle hair, intellectual impairment, decreased fertility, and short stature have been studied. Electrophoresis of the SCM-structural proteins showed that the alpha polypeptides appeared normal, but the matrix component was markedly reduced. This was confirmed by finding a normal alpha X-ray diffraction pattern but a reduced 1/2 cystine content of hair and an abnormal stress-strain curve. Electron-microscopic studies revealed extreme disorganization of the filaments which most likely resulted from the absence of normal cross-linking. Nails, which contain structural proteins similar to hair, also showed the abnormality. Since the matrix component seen by electrophoresis consists of more than one component the defect cannot be explained as a single structural gene abnormality.
Amino Acids↗
Dominantly inherited osteogenesis imperfecta in man: an examination of collagen biosynthesis.
We have examined control subjects and patients in an effor to discover a metabolic basis for dominantly inherited osterogenesis imperfecta (OI). Studies were carried out in vitro with cultured skin fibroblasts obtained from OI patients, and in vivo on peptide-bound hydroxyproline excretion in urine. Urinary hydroxyproline excretion (milligrams/24 hr) adjusted for age is essentially normal in OI patients, although the mean excretion rate is below average. The latter finding is presumably a reflection of the smaller body mass of OI patients. The OI skin fibroblasts, matched for age of donor, site of biopsy, phase of growth, and generation number in culture, incorporated L-proline into hot trichloroacetic acid (TCA)-soluble protein (collagen) at normal rates. The rate of conversion of proline to hydroxyproline in the nascent polypeptides is also normal in OI. Incorporation of L-lysine was also normal in OI. These findings indicate that peptide synthesis of collagen is not impaired in OI. Rates of galactose incorporation into collagen and the extractability of collagen into normal saline or 0.2 M citric acid were all normal both in OI cells and in the culture medium recovered from the monolayer. These findings, in combination with the urinary data on hydroxyproline excretion in vivo reveal that cross-linking and export of collagen in OI is essentially normal. The elution profile after ion exchange chromatography of fibroblast collagen on carboxymethyl (CM)--Sephadex was also examined. The normal 2/1 ratio of peak 1 (largely alpha 1(1) chains) to peak 2 ) largely alpha 2 chains) was found in OI fibroblast extracts, which implies that synthesis and initial aggregation of the two types of polypeptide to yield (alpha1(1))-2 alpha 2 collagen composition is not abnormal in OI. Despite the negative biochemical findings, a consistent defect in the morphology of OI cells was identified in the log phase and the confluent phase of monolayer cultures. The finding is characterized by irregular packing of the aggregated cells and by an irregular tessellated appearance of the individual OI fibroblast. This observation reassures us that the inherited defect is expressed in vitro.
Adolescent↗
A simple combinatorial method for calculating genetic risks.
A method is presented whereby genetic counsellors can calculate genetic risks in a wide variety of circumstances using only arithmetics. The method is general in that it can handle such information as gene frequency, mutation rate, mode of inheritance, penetrance, pedigree to which the consultand belongs, phenotype of the consultand and his relatives, biochemical findings, etc. Each of the possible combinations of genotypes which may be present in the pedigree is listed and considered in turn. The method consists of a series of simple steps leading mechanically to the right answer.
Computers↗