Molecular mechanism of Angelman syndrome in two large families involves an imprinting mutation

Article Abstract:

The molecular mechanism of Angelman syndrome (AS) has been studied in two large families with the finding that there is an imprinting mutation. In several patients in the past microdeletions upstream of the SNRPN (ital) gene have been seen, defining an imprinting center (IC) hypothesized to regulate the imprint switch process in the male and female germlines. In the families an AS imprinting mutation was segregated. One of the families was described in an earlier genetic linkage of AS to 15q11-q13. The original linkage is for the 15q11-q13 IC. Affected patients in the AS families have either a 5.5- or a 15-kb microdeletion, one of which narrowed the shortest region of deletion overlap to 1.15 kb in all the cases. The small region defines a component of the IC involved in AS, the paternal-to-maternal switch element. Genetic counseling issues for AS and Prader-Willi syndrome are brought out by the research.

Planning, Abnormalities, Brain, Familial diseases, Genetic counseling, Brain abnormalities, Heredity, Human, Human heredity

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Imprinting-mutation mechanisms in Prader-Willi syndrome

Article Abstract:

Imprinting-mutation mechanisms have been studied in Prader-Willi syndrome (PWS). A series of familial PWS cases has been identified. One case had a deletion of 7.5 kb. The critical region has been narrowed down to less than 4.3 kb spanning the SNRPN gene CpG island and exon 1. With other findings, this suggests promoter elements at SNTPN that play a key role in initiating imprint switching in spermatogenesis. Three patients with sporadic PWS and an imprinting mutation (IM) with no detectable mutation in the imprinting center (IC), a region which controls resetting of parental imprints in 15q11-q13 in gametogenesis, were found. The maternal-to-paternal imprint during parental spermatogenesis was perhaps not switched because of developmental or stochastic failure. The epigenetic effect of an IM in the parental germ line determined the phenotypic effect in the patient, a novel mechanism in human disease.

Japan, Germany, Physiological aspects, Gene mutations, Gene mutation, Mutation (Biology), Mutation

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A new genetic disorder in mitochondria fatty acid [beta]-oxidation: ACAD9 deficiency

Article Abstract:

Three cases having acyl-CoA dehydrogenase 9 (ACAD9) deficiency with episodic liver dysfunction during otherwise mild illness or cardiomyopathy, along with chronic neurologic dysfunction, are reported. The studies of the tissue distribution and gene regulation of ACAD9 and very-long-chain acyl-CoA dehydrogenase have identified the presence of two independently regulated functional pathways for long-chain fat metabolism, showing that these two enzymes might be involved in different physiological functions.

Science & research, DNA binding proteins, Fatty acid metabolism, Fatty acid desaturases

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