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Biomedical subjects

D B Pitt

Publications and source records attributed to D B Pitt.

At least 19 recordsLinked to original sources
PubMed1993

Comparison of genotype and intellectual phenotype in untreated PKU patients.

We have screened 55 untreated phenylketonuria patients from 42 families for common mutations of the phenylalanine hydroxylase gene and determined both causative alleles in 12 families. The correlation between genotype and intellectual phenotype of patients in these families was examined. Our results were compared to a study which predicted phenylalanine hydroxylase activity based on genotype and examined its correlation with the biochemical phenotype of treated patients. Some of the intellectual phenotypes of patients in our study correlated well with the predicted activities. However, we found one family with a genotype expected to have no activity of phenylalanine hydroxylase where the patients were not severely retarded. Major differences in intellectual phenotype were found in patients with the same genotype both between unrelated subjects and within families, suggesting that there is not a simple correlation between genotype and intellectual phenotype.

Alleles↗
PubMed1991

Phenylketonuria does not cause cataracts.

In a study of 46 adults aged 28-71 years with untreated phenylketonuria (PKU) there were 3 (6.5%) with cataracts. This incidence was similar to that in the Australian population and in a control series of intellectually disabled adults. Only two of the PKU patients with cataracts could be examined by slit-lamp biomicroscopy and in both the findings suggested that the prolonged use of phenothiazines may have played a role. Slit-lamp examination of a further ten untreated PKU patients and 13 PKU adults who had been treated in childhood revealed only small lens opacities (in 40%) of a type found in 72.7% of a control group. The study provides no support for claims that PKU can cause cataracts.

Adult↗
PubMed1991

The natural history of untreated phenylketonuria over 20 years.

Fifty-one adults with untreated phenylketonuria (PKU), have been reviewed after a 20 year interval, at ages ranging from 28.8 to 71.8 years. Five died of causes unrelated to PKU. Three severely affected individuals had shown a progressive loss of motor function and three had developed epilepsy, bringing the total with this problem to 12. No loss of abilities was apparent in 41 patients. Other health problems, including cataracts, were not frequent. Serum phenylalanine levels had decreased over the 20 year period. Untreated PKU does not generally cause progressive loss of abilities during adult life.

Activities of Daily Living↗
PubMed1988

Maternal phenylketonuria: successful outcome in four pregnancies treated prior to conception.

The management of four pregnancies in two phenylketonuric women is described. A successful outcome in these pregnancies is ascribed to the initiation of treatment prior to conception and the maintenance of tight control with serum phenylalanine between 100 and 400 mumol/l throughout the gestation period. A trial of diet is desirable before a decision is made about pregnancy and before contraception is ceased. Close contact must be maintained with female phenylketonurics throughout their reproductive life to ensure that this process is followed.

Child↗
PubMed1982

Fragile (X)(q27) sites in a pedigree with female carriers showing mild to severe mental retardation.

A pedigree showing the fragile site at Xq27 in a severely retarded female and in other less retarded carriers is described. Two of the four moderately retarded males with the fra(X)(q27) show macro-orchidism, and a variety of other features usually used to support the effects of the fra(X)(q27) are also inconsistent. A second fragile site at (10)(q23) is also present and in the two oldest females its frequency is not decreased, whereas the fra(x)(q27) is not detectable in these females although probably present. It is concluded that pedigrees showing mentally retarded females and probable X linkage should be included in studies of the fra(X)(q27).

Adult↗
PubMed1977

Stress deficiency of the T-lymphocyte system exemplified by Down syndrome.

A comparison of immune competence in 26 patients with Down syndrome in an institution and 26 matched healthy controls revealed an atypical pattern of T-cell immunodeficiency in the Down-syndrome patients. The patients with Down syndrome had a lymphocytosis in blood with high counts of T (and B) cells, but with impaired effector function of T cells as judged by anergy to dinitrochlorobenzene, low responsiveness to ubiquitous antigens which elicit delayed-type hypersensitivity reactions, and low mitogenic activity of non-stimulated and phytohaemagglutinin-stimulated lymphocytes in culture. Helper-T-cell function measured by the humoral immune response to flagellin was intact, and there were minor abnormalities of the B-cell system. Attempted restoration of T-cell function with levamisole was unsuccessful. This pattern of T-lymphocytosis with impaired effector function could be explained by "stress-deficiency" of the immune system consequent upon a heavy load of infection in early life.

Adolescent↗
PubMed1976

An anomaly in the inheritance of haptoglobin types in Down's syndrome: a study of mother-child pairs.

A sample of 95 mother-child pairs provided evidence that plasma haptoglobin (Hp) types are inherited in an unusual manner by children with Down's syndrome. Homozygous mothers gave birth to more homozygotes and fewer heterozygotes than expected. Among offspring of heterozygous mothers, the frequencies were distributed essentially as expected. No abnormality was found in a normal control sample of 151 mother-child pairs. Using this material it was demonstrated that the anomalous Hp inheritance in Down's syndrome was not due simply to an increase in maternal age when the children were born.

Adolescent↗