Simple ultra-microtechniques for genetic complementation analysis and early prenatal diagnosis of sphingolipidoses

Two patients with an unusual form of type II fucosidosis

Two brothers with an unusual form of fucosidosis are presented, providing further evidence for the clinical heterogeneity of the disease. The patients have several characteristics of type II, but from the point of view of progression rate and survival, they resemble more type III. However, the characteristic skin lesions of type III are not seen. In contrast to all other subtypes, a dry, thin skin is observed. The authors tend to classify these patients as a "slow motion" type II variant. Both in leukocyte lysates and plasma, severe alpha-L-fucosidase deficiency was established. In the parents, intermediate alpha-L-fucosidase activities were observed in leukocytes, but normal values in plasma, indicating that plasma is not suitable for carrier detection in this family. It is felt that no conclusions regarding clinical subtypes of fucosidosis can be drawn without careful characterization of the mutant enzyme in the primarily affected tissues.

High alkaline phosphatase activity in isoproterenol stimulated fibroblast cultures from patients with numerically unbalanced chromosomal aberrations

Treatment of cultured fibroblasts from patients with unbalanced chromosomal aberrations with a mixture of isoproterenol, theophylline and ascorbic acid resulted after 48 hours in an at least three-fold increase of alkaline phosphatase activity on a per cell basis, whereas cells from normal healthy individuals did not show this dramatic response. Cells were studied from patients with trisomy 21 (14 cases), trisomy 18 (3 cases), trisomy 13 (1 case), pentasomy X (1 case), Turner syndrome (2 cases), and Klinefelter syndrome (1 case), and no exception was noted. The mechanism of this phenomenon is not clear, but it is speculated that increased cyclic-AMP levels caused by the action of isoproterenol on adenylcyclase may account for excessive reactions of unbalanced cells as compared to normal cells. This simple biochemical diagnostic procedure might become useful in screening programs for unbalanced chromosomal abberations.

Reliable diagnosis of the major type of cystic fibrosis with fibroblast cultures. A double blind study

A double blind study has been carried out to demonstrate that the most common type of cystic fibrosis (CF) can be reliably diagnosed with skin-derived fibroblast cultures. Alkaline phosphatase (AIP) activity has been measured in 6 normal controls, 12 CF-heterozygotes and 6 CF-homozygotes before and after stimulation with Tamm-Horsfall-glycoprotein (THP), isoproterenol and theophyline ("THP-induction test"). The mean AIP-activities after THP-induction were 8.8, 12.7 and 34.6 for the three different genotypes respectively. There was no overlap between the values of CF-homozygotes on the one hand, and the values of CF-heterozygotes and normal controls on the other hand. All 24 specimens were correctly diagnosed in the present double blind study, indicating the very high degree of reliability of the THP-induction test in the detection of the predominant type of cystic fibrosis with fibroblast cultures. Normal controls and CF-heterozygotes could not be discriminated on an individual basis, but as a group the CF-heterozygotes displayed higher AIP-values.