Fróðskaparrit - 01.01.1975, Page 8

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Amylo-l,6-glucosidase deficiency
Table 1. Amylo-l,6-glucosidase activity of leucocytes (glucose, nmole/g
protein/min) and erythrocytes (glucose, nmole/g haemoglobin/min) in pati-
ents, definite heterozygotes and in normal controls.
Patients (n = 7) Parents (n = 9) Controls (n =18)
Leucocytes
Mean 0.12 1.51 3.04
Median 0 1.33
Range 0—0.48 0.49—2.56 1.62—4.48
Erythrocytes
Mean 0.122 0.126 0.225
Median 0.120 0.113
Range 0.109—0.136 0.105—0.229 0.153—0.363
family, also connected with the other probands, but it was
not possible to determine the exact relationship.
As heterozygosity could not be diagnosed with certainty by the methods
used in the present study it was impossible to perform ordinary linkage
studies. It was, however attempted to look for possible associations within
sibships between a factor influencing the enzymatic level and each of the
marker systems taken separately. If sib pairs alike with respect to a given
marker show significantly lower activity differences than those sib pairs
which present dissimilarity with respect to the marker, this may be a
reflection of genetic linkage with the gene determining the level of enzyme
activity. Lack of significant associations does not in any way exclude
linkage as it may i.a. be caused by the fact that the methods employed
reflect the genetic variation very poorly. When sibships showing variation
with respect to a given marker were used in the analyses, all results
were non-significant except for the comparison between ADA phenotypes
and enzyme levels. The mean intrapair enzyme activity difference was
found to be significantly lower (P between 0.05 and 0.01) in ADA identi-
cal than in ADA different sib pairs.
The serological markers were also used to check the alleged biological
relationships. It appeared most likely that individuals IV, 53 and 54,
according to the results obtained in the MNSs and the HL-A systems
and considering the rarity of crossing-over in these systems, had only
their mother in common with the remaining members of the sibship
(individuals 55—60). In the sibship comprising individuals V. 112, 113
and 114 one of the haplotypes observed in no. 112 was not seen in any
of the parents, nor in the two sibs; the results obtained in the Rh system