Separation of chromatids of all mitotic chromosomes, here called total premature chromatid separation (total PCS), was observed in 67 to 87.5% of repeated cultures of peripheral blood lymphocytes from two unrelated infants. Also noted was a variety of mosaic aneuploidies, especially trisomies, double trisomies, and monosomies, to be called mosaic variegated aneuploidy. The infants both showed severe pre- and postnatal growth retardation, profound developmental retardation, uncontrollable seizures, severe microcephaly, hypoplasia of the brain, Dandy-Walker anomaly, abnormal facial appearance, and bilateral cataract. Patient 1, a girl, in addition had a cleft palate, multiple renal cysts, and Wilms tumor of the left kidney. Whereas patient 2, a boy, had ambiguous external genitalia. They both died within 2 years of age. In the two families of the infants, their parents and three other members showed 2.5 to 47% lymphocytes with total PCS but without mosaic variegated aneuploidy or phenotypic abnormalities. Another 10 relatives studied showed 0 to 1% cells with total PCS and so were judged negative for the total PCS trait. It was deduced that the total PCS trait in the two families was transmitted in an autosomal-dominant fashion, and the two affected infants were homozygous for the trait.

Fatty acids of plasma and erythrocyte membrane sphingomyelin were determined by gas chromatography-mass spectrometry in adrenoleukodystrophy (ALD) without adrenal insufficiency. Mass chromatogram tracing with the ion at m/z 143 [(CH2)6COOH3]+ showed increases of saturated very long chain fatty acids in plasma and erythrocyte membrane sphingomyelin in ALD. The C26:0/C22:0 ratios in plasma were 0.121, 0.057 and 0.007 in cases 1 and 2, and a control subject, respectively. The C26:0/C22:0 ratios in erythrocyte membrane sphingomyelin were 0.386, 0.211 and 0.093 in cases 1 and 2 and the control subject, respectively. The demyelinating process of ALD was clearly observed in both the inversion recovery 2100/500 and spin echo 2100/80 scans on magnetic resonance imaging. The magnetic resonance image in case 1 revealed widespread demyelinated lesions, involving almost the entire cerebrum and cerebellum, at 4 years after the onset, while that in case 2 revealed demyelinated lesions mainly limited to parieto-occipital areas at 1 year after the onset.

Isk is a small membrane protein with a single membrane-spanning domain and shows a slow voltage-dependent K+ channel activity. Mutational analyses showed that Isk forms an integral part of the K+ channel itself. Two other proteins have similar properties, suggesting a new group of voltage-dependent channels.

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