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K Eggermann

Publications and source records attributed to K Eggermann.

26 records · Page 2Linked to original sources
PubMed1997

Molecular studies in 37 Silver-Russell syndrome patients: frequency and etiology of uniparental disomy.

We report studies on the etiology of uniparental disomy (UPD) in Silver-Russell syndrome (SRS) patients. Thirty-seven SRS families were typed with short tandem repeat markers from chromosomes 2, 7, 9, 14, and 16. UPD for these chromosomes has either been described in association with growth retardation or has been observed in confined placental mosaicism, a mechanism that may result in UPD. Maternal UPD7 was detected in three SRS patients, accounting for approximately 10% of the tested SRS patients. These results agree with previously published studies. The allelic distribution in one of the three families indicates complete isodisomy, whereas allelic patterns in the other two families are consistent with partial and complete heterodisomy, respectively, suggesting that, in the latter cases, UPD originates from maternal meiosis, whereas in the first case, it seems to be of mitotic origin. STR typing for UPD of chromosomes 2, 9, 14, and 16 showed no abnormalities. Our results demonstrate the necessity of screening SRS patients for UPD7, although the effect of UPD7 cannot be correlated with the SRS phenotype as yet. An association between UPD for the other investigated chromosomes and SRS seems to be negligible.

Abnormalities, Multiple↗
PubMed1996

Efficacy and side-effects of clozapine: testing for association with allelic variation in the dopamine D4 receptor gene.

Genetic factors are supposed to play a major role not only in the etiology of psychiatric disorders but also in individual response to medications. To test the hypothesis that inter-individual differences in response to clozapine and the occurrence of side-effects might be influenced by variations in the dopamine D4 receptor gene, we examined frequencies of four known polymorphic sites affecting protein structure in the dopamine D4 receptor gene in 149 patients with schizophrenia or schizoaffective disorder treated with clozapine. The D4 polymorphisms included a 13-base pair deletion, which through a frameshift leads to a truncated nonfunctional receptor protein. There were, however, no significant differences in genotype counts between responders and nonresponders. Furthermore, no side-effect was found to be associated with genetic variants of the dopamine D4 receptor.

Adult↗
PubMedDate not supplied

Formation of uniparental disomy 7 delineated from new cases and a UPD7 case after trisomy 7 rescue. Presentation of own results and review of the literature.

Maternal uniparental disomy for the entire chromosome 7 (matUPD7) has been reported several times in Silver-Russell syndrome (SRS) and growth-restricted patients. Here we present our results from the analysis of an abortion with confined placental mosaicism (CPM) for trisomy 7 which showed a maternal meiotic origin of the trisomy in the placenta and rescue to maternal UPD7 in foetal membrane. Furthermore, two newly detected SRS cases with maternal UPD7 revealed isodisomy and partial heterodisomy, respectively. Summarising these results with those published previously on the origin of UPD7, similar numbers of isodisomy (n=11) and cases with complete or partial heterodisomy (n=12) have been reported. In respect to the different formation mechanisms of UPD, complete isodisomy should be the result of a post-zygotic mitotic segregation error, whereas heterodisomic UPDs should be caused by trisomic rescue after meiotic non-disjunction events. In maternal UPD7, 50% of cases seem to be caused by post-zygotic mitotic segregation errors, which is similar to the situation in trisomy 7. This result corresponds to the situation in trisomy 8 but is in contrast to observations in the frequent aneuploidies. Thus, the different findings in these aberrations reflect the presence of multiple factors that act to ensure normal segregation, varying in importance for each chromosome.

Abnormalities, Multiple↗
PubMedDate not supplied

Origin of uniparental disomy 6: presentation of a new case and review on the literature.

Paternal uniparental disomy (UPD) of chromosome 6 has been reported several times in patients with (transient) neonatal diabetes mellitus ((T)NDM). Here we present our short tandem repeat typing results in a new patient with NDM, revealing a paternal isodisomy (UPiD). Summarising these data with those published previously on complete paternal (n=13) and maternal (n=2) UPD6, all cases show isodisomy. In general, several modes of UPD formation have been suggested: While a meiotic origin of UPD mainly results in a uniparental heterodisomy (UPhD), UPiD is probably the result of a post-zygotic mitotic error. This mode of formation consists of a mitotic nondisjunction in a disomic zygote, followed by either a trisomic rescue or a reduplication. Endoduplication in a monosomic zygote is another possible but less probable mechanism, taking into consideration that monosomic zygotes are not viable. The exclusive finding of isodisomy in case of chromosome 6 therefore gives strong evidence that segregational errors of this chromosome are mainly influenced by postzygotic factors. This hypothesis is supported by the observation of two cases with partial paternal UPiD6 originating from mitotic recombination events. The influence of mitotic segregational errors in UPD6 formation is in agreement with the results in trisomy/UPD of other chromosomes of the C group (7 and 8), and is in remarkable contrast to the findings in studies on the origin of the frequent aneuploidies. Multiple factors ensure normal segregation and we speculate that they vary in importance for each chromosome.

Chromosome Aberrations↗