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The interpretation of genetic risks offered in genetic counselling
170
H U M A N GENETICS SOCIETY 01-AUSTRALASIA
Pathology (l981), 13, January
patients with Ph' + CGL were investigated by C-banding. Increased size variation in the C-bands ofchromosome 1 wiis found in 1 1 patients and absolute heteromorphism of pair 9 in all patients. Chromosome 16 showed a low liequency. I t wiis noted that the translocation could occur onto either of the pair of 9 chromosomes, but that it was clonal. When the translocation was onto the 9 with the smaller heterochromatin, additional abnormalities developed in blastic transformation. but when the 9 with the largcr heterochromatin was involved, no additional abnormalities dcveloped in blastic transformation. This suggests an association between heteromorphism of chromosome 9 and mitotic dysfunction in this disease. GENETIC SYNDROMES OF THE EOSINOPHIL GRANULOCYTE
H. SMITH Department of Hnmnxitohgy. Royul Brishanc. Hospital Three families are described with structural changes in eosinophil granulocytes. The main value of noting these anornaliea I \ the insight they may give into the genealogy or function of the eosinophil. In one the anomaly wiis inherited in dominant fashion, in the other 2 no other members were affected and it is assumed that if the anomaly is inherited the pattern is autosomal recessive. I . A dominantly inherited disorder in which cosinophils and basophils contained bodies staining green with standard stains: the restriction of thc anomaly to eosinophils and basophils indicates that these are related more closely to each other than either is to the neutrophil. There was no associated clinical abnormality. 2. An inherited anomaly similar to I , but no other family members affected, ultrastructurally distinct, and affecting all 3 types of' granulocytes and monocytes. The pattern is in agreement with present notions of granulocyte and monocyte genealogy. The anomaly w ,ociated with extrahepatic biliary atresia and livido rcticularis of the skin. 3. lnclusionc staining orange by standard procedures in rare eosinophils in twins affected by failure to thrive and coeliac likc syndrome: this may be a'new syndrome. THE INTERPRETATION OF GENETIC RISKS OFFERED IN GENETIC COUNSELLING
J O H N PEA RN Dq~arimewtof' Child Health. Royal Chikhrn :r Ho.rpi/ul, Brishanr The final common path of many practical endeavours in clinical genetics, is the proffering of recurrence risks to parents who have had a previous child with a genetic disease. Thus karyotyping, biochemical carrier detection studies, and mathematical approaches such as Bayesian techniques, all have as their common end the calculation of ii simple mathematical risk. The consumer acceptance of such risks, that is how the client interprets the proffered risk, is perhaps the most practical aspect of all clinical genetics. Age, personality, prior knowledge of the risk, the 'risky-shift' phenomenon. anticipated risk, and an understanding of the general risk background are all important factors which modify the subjective interpretation of risk. The subjective risk scale used by individuals who are confronted with a situation of uncertain outcome, has a finite number of discrete intervals, and is not a continuurn. Eighty per cent of geneticists themselves use a subjective risk scale of between 5 and 12 intervals, and this scale is neither an arithmetic or a ratio scale, and is in part nominal. In practical genetic counselling, the subjective risk hcnles of the counscllor and clicnt may not be similar. The counsellor and client often use different risk scales to interpret the fixed mathematical risk involved-scales which differ not only in size ofrisk intervals, but also in the pattern of such intervals along the length of the subjective risk scale. THE PURPOSE AND METHOD OF MAINTAINING GENETIC RECORDS
ATHEL HOCKEY Genetic Counsellinx Clinics, Princess MarXaret Hospital for Children and King Edward Mrmoriul tfospitol for Women, Perth The cstablishment of a genetic counselling service involves the keeping of standardized case records. My own experience at the Maternity and Children's Hospital in Perth is presented to show how and why this was done. Computerization was found to have advantages over an initial punch card system in that it allowed for the handling o f i i larger series with inclusion of more data and opportunity for linkage of variables and families. I t provided for regular updating and the quick retrieval of information. Diagnostic groups were studied and related to spwific gmrtic rc,gistc~r.s. Our system has 5 cards which give details of( I ) identification, (2) demography, (3) diagnosis, mode of inheritance ond risk. (4) tests including prenatal diagnosis and outcome, ( 5 ) pedigree data with a limited number of surnames. 1556 families representing a heterogenous group of disorders have now been coded. Thirty-four per cent were seen
H U M A N GENETICS SOCIETY 01-AUSTRALASIA
Pathology (l981), 13, January
patients with Ph' + CGL were investigated by C-banding. Increased size variation in the C-bands ofchromosome 1 wiis found in 1 1 patients and absolute heteromorphism of pair 9 in all patients. Chromosome 16 showed a low liequency. I t wiis noted that the translocation could occur onto either of the pair of 9 chromosomes, but that it was clonal. When the translocation was onto the 9 with the smaller heterochromatin, additional abnormalities developed in blastic transformation. but when the 9 with the largcr heterochromatin was involved, no additional abnormalities dcveloped in blastic transformation. This suggests an association between heteromorphism of chromosome 9 and mitotic dysfunction in this disease. GENETIC SYNDROMES OF THE EOSINOPHIL GRANULOCYTE
H. SMITH Department of Hnmnxitohgy. Royul Brishanc. Hospital Three families are described with structural changes in eosinophil granulocytes. The main value of noting these anornaliea I \ the insight they may give into the genealogy or function of the eosinophil. In one the anomaly wiis inherited in dominant fashion, in the other 2 no other members were affected and it is assumed that if the anomaly is inherited the pattern is autosomal recessive. I . A dominantly inherited disorder in which cosinophils and basophils contained bodies staining green with standard stains: the restriction of thc anomaly to eosinophils and basophils indicates that these are related more closely to each other than either is to the neutrophil. There was no associated clinical abnormality. 2. An inherited anomaly similar to I , but no other family members affected, ultrastructurally distinct, and affecting all 3 types of' granulocytes and monocytes. The pattern is in agreement with present notions of granulocyte and monocyte genealogy. The anomaly w ,ociated with extrahepatic biliary atresia and livido rcticularis of the skin. 3. lnclusionc staining orange by standard procedures in rare eosinophils in twins affected by failure to thrive and coeliac likc syndrome: this may be a'new syndrome. THE INTERPRETATION OF GENETIC RISKS OFFERED IN GENETIC COUNSELLING
J O H N PEA RN Dq~arimewtof' Child Health. Royal Chikhrn :r Ho.rpi/ul, Brishanr The final common path of many practical endeavours in clinical genetics, is the proffering of recurrence risks to parents who have had a previous child with a genetic disease. Thus karyotyping, biochemical carrier detection studies, and mathematical approaches such as Bayesian techniques, all have as their common end the calculation of ii simple mathematical risk. The consumer acceptance of such risks, that is how the client interprets the proffered risk, is perhaps the most practical aspect of all clinical genetics. Age, personality, prior knowledge of the risk, the 'risky-shift' phenomenon. anticipated risk, and an understanding of the general risk background are all important factors which modify the subjective interpretation of risk. The subjective risk scale used by individuals who are confronted with a situation of uncertain outcome, has a finite number of discrete intervals, and is not a continuurn. Eighty per cent of geneticists themselves use a subjective risk scale of between 5 and 12 intervals, and this scale is neither an arithmetic or a ratio scale, and is in part nominal. In practical genetic counselling, the subjective risk hcnles of the counscllor and clicnt may not be similar. The counsellor and client often use different risk scales to interpret the fixed mathematical risk involved-scales which differ not only in size ofrisk intervals, but also in the pattern of such intervals along the length of the subjective risk scale. THE PURPOSE AND METHOD OF MAINTAINING GENETIC RECORDS
ATHEL HOCKEY Genetic Counsellinx Clinics, Princess MarXaret Hospital for Children and King Edward Mrmoriul tfospitol for Women, Perth The cstablishment of a genetic counselling service involves the keeping of standardized case records. My own experience at the Maternity and Children's Hospital in Perth is presented to show how and why this was done. Computerization was found to have advantages over an initial punch card system in that it allowed for the handling o f i i larger series with inclusion of more data and opportunity for linkage of variables and families. I t provided for regular updating and the quick retrieval of information. Diagnostic groups were studied and related to spwific gmrtic rc,gistc~r.s. Our system has 5 cards which give details of( I ) identification, (2) demography, (3) diagnosis, mode of inheritance ond risk. (4) tests including prenatal diagnosis and outcome, ( 5 ) pedigree data with a limited number of surnames. 1556 families representing a heterogenous group of disorders have now been coded. Thirty-four per cent were seen