Biomedical subjects
G S Gericke
Publications and source records attributed to G S Gericke.
Fragile collagen and the lethal multiple pterygium syndrome: does heat stress play a role?
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Genetically determined hyperthermic reactivity associated with certain congenital abnormalities.
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An association between certain congenital abnormalities and the malignant hyperthermia trait.
Although an association between malignant hyperthermia (MH) and congenital abnormalities has been recorded, no prospective study has been attempted to investigate this relationship. Standardised in vitro muscle tests were performed, because of impending anaesthesia for corrective surgery, on 25 children with birth defects similar to those induced by hyperthermia in laboratory animals, and in whom excessive pyrexial reactivity to anaesthesia, drugs or stress were recorded. Fifteen of the 25 children were MH positive by responding abnormally to the administration of halothane/caffeine. Five of these patients reacted positively to both caffeine and halothane, while the remainder manifested a contractile response to halothane only. This study underlines the existence of an anaesthetic risk factor associated with certain congenital abnormalities and neurodevelopmental delay and emphasises the need for further research to elucidate the possible importance of heat stress during fetal development in genetically susceptible individuals.
Temperature-sensitive genes in reproductive and developmental biology--almost 30 years from fruitfly to bedside.
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The role of human genetics in society: implications for legal involvement.
The tools and techniques of human genetics are very much part of medicine in the 1990s and beyond. Man's motivation for self improvement has been an integral part of his make-up since time immemorial. The human desire for preserving the fittest and weeding out the worst remains the same since stone-age man practised castration, coitus interruptus, mechanical contraception, urethral surgery, abortion, infanticide, infant cannibalism, delayed lactation and geronticide. During the intervening centuries there have been scores of attempts to develop dream states; at forced mass migration, or to protect social order by casting out the unwanted under various guises. For the first time we are catching a glimpse of the possibility of significantly altering our genetic constitution, supplying us with the tools to realize very deep seated instincts, but without adequate knowledge of all the dangers. It is foreseen that the law has an important contribution in maintaining the balance between seemingly conflicting interests of the individual, the community, the state and genetic research scientists. There is a need for pro-active involvement in the author's opinion.
Does heat damage fetuses?
Temperature affects phenotypic variation during critical developmental stages in all forms of life that have been studied thus far. In animal studies of heat teratogenicity, adverse effects have ranged from disruption of the normal cell cycle leading to decreased numbers of cells, to the induction of developmental abnormalities by means of embryonic cell death. The heat shock response is a universal cellular stress reaction in which the transcriptional and translational mechanisms of the cell are pre-empted by preferential induction of heat shock protein synthesis. Occurrence of such a phenomenon during prenatal life could lead to the absence of essential gene products at critical stages of development. The crucial question of whether temperature induced cellular and genetic effects ever occur during human fetal development has been considered only in relation to maternal hyperthermia, which is generally viewed as not being of significance in human teratology. We propose that teratogenicity may result from fetal hyperthermia unrelated to maternal hyperthermia, caused either by impaired fetomaternal heat dissipation due to reduced placental blood flow (extrinsic fetal hyperthermia) or by increased fetal heat production during hypermetabolic states (intrinsic fetal hyperthermia). The need for further studies in this regard is emphasized.
Focal dermal hypoplasia (Goltz syndrome): case reports.
Two Cape Coloured children, both with physical stigmata of Goltz syndrome, are described. Accurate diagnosis of congenital defects in the newborn allows optimal planning of surgical treatment and more accurate prognosis and genetic counselling.
Another phenocopy for chondrodysplasia punctata in addition to warfarin embryopathy?
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Leucocyte ultrastructure and folate metabolism in Down's syndrome.
Electron microscopical and haematological investigation of peripheral blood has shown a higher percentage of leukaemia-like nuclear ultrastructural abnormalities in the leucocytes of 30 individuals with Down's syndrome (mean 6.3%) than in normal controls (mean less than 1%). Most of these aberrations consisted of nuclear membrane abnormalities. Red cell folate values were very low in the group with Down's syndrome. Although mean serum folate and vitamin B12 levels were normal in this group, these individuals displayed increasing macrocytosis and decreasing serum folate levels with age. The whole group with Down's syndrome showed an increased mean corpuscular volume (MCV). The percentage of ultrastructural abnormalities did not correlate with folate levels when they were analysed individually. The existence of nuclear membrane abnormalities and folate deficiency, both of which may be associated with increased chromosome breakage, may be partly responsible for the increased leukaemia risk in patients with Down's syndrome.
Leukaemogenesis in Down's syndrome.
Due to the fixed karyotype and documented malignancy risk in patients with Down's syndrome, recently described aetiological factors can be assigned to their proper places in a conceptual framework for leukaemogenesis in these individuals. This is a more profitable approach than those in which various types of karyotypic patterns are matched to different malignancies. It seems that viruses may play a special role, but they need interaction with other factors, most of which are present in Down's syndrome. A unifying concept which may be helpful in establishing research priorities is presented.
Mucolipidosis III: two patients displaying genetic pleiotropism.
Two Cape Coloured siblings with typical features of Hurler's syndrome, but without mucopolysacchariduria or mucopolysaccharide accumulation in tissues, are presented. The clinical features, in conjunction with raised beta-D-galactosidase and alpha-L-fucosidase levels in fibroblast cultures from one of the patients, suggest the diagnosis of a mucolipidosis. Theories relating to the intracellular deficiency and extracellular excess of lysosomal enzymes in these conditions are reviewed. Phenotypical and cell culture differences between 2 siblings who display the same overall clinical syndrome, illustrate the genetic pleiotropism inherent in this group of diseases.
[Letter: Constricting dystrophy of the thorax in the neonate (Jeune syndrome)].
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Clinical and cytogenetic aspects of the 21 deletion syndrome.
The clinical, cytogenetic and dermatoglyphic findings in a patient with a ring chromosome 21 are presented. This anomaly acts as a deletion of chromosomal material and results in specific congenital defects. A comparison is made with 24 cases of deletions involving chromosome 21 described in the literature. Six of these have been studied by means of recently developed chromosome banding techniques. Cases presumably arise through somatic non-disjunction or chromosome breakage. When the chromosomes of both parents are normal the recurrence risk is negligible.
[Problems with reference to genetic counseling in arthrogryposis multiplex congenits].
Arthrogryposis multiplex congenita (AMC) is a rare condition, which presents various problems to the genetic counsellor. Two cases are described and the possible modes of inheritance are discussed. A review of the literature in this respect favours an autosomal recessive inheritance which is, however, not applicable to all cases.
[Clinical characteristics and genetic identity of the basal cell nevus syndrome (Gorlin-Goltz syndrome)].
The clinical, genetic, radiological, dental and dermatological aspects of 3 patients with the autosomal dominant basal cell naevus syndrome are reported. An analysis of the phenotypic features of 72 cases described in the literature is presented and compared with a previous analysis. Ash leaf hypopigmentation similar to that found in tuberous sclerosis represents a unique finding in this syndrome. Other similarities to the phacomatoses are discussed. We were able to support a previous report that patients with the basal cell naevus syndrome have a normal end-organ response to parathormone stimulation, and that it is most probably not related to pseudohypoparathyroidism, as earlier reports suggested.
[Early diagnosis of disorders in the human fetus].
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