234
194
118
72
M 123456
205 bp ....
176
bp
70
bp
29
bp
primers
ofthe HCCAA allele, whereasnoncarriers produce
only the short fragments (Fig. 3) (18).
The diagnostic tests, by Southern blot analysis
or the PCR-based procedure, have now been
carried out on 193 individuals, including the fetus
for prenatal diagnosis. Twenty-six patients and
11 young asymptomatic at-risk relatives have
been found to have the HCCAA-causing muta–
tion, all of whorn are heterozygous for the muta–
tion. Ninety-seven unrelated individuals, 11
LEGEND FOR FIG. 3
Agarose gel electrophoresis of
Alul
digested arnplified DNA
for diagnosis of HCCAA. The amplified DNA segment,
containing the HCCAA-related variable
Alul
restriction site
and an additional nonvariable A/u/restriction site, is digested
with
Alu/
and electrophoresed on a 4% agarose gel. Diges–
tion of PCR products from the normal and the HCCAA–
relatedcystatin C alleles with
Alu/
results in fragments of 176
and 29 bp or 205 bp, respectively, in addition to a non–
variable 70-bp fragment. The arrow indicates the 205-bp
fragment, which is the marker for HCCAA. Lanes 2, 4, and
5, samples from individuals with manifest HCCAA; Ianes
1,3, and 6, sarnples from individuals with no clinical signs of
the disease. The sizes of relevant fragments from
Hae//1
digested FX174 DNA (Jane marked M) are indicated.
spouses, and 48 at-risk relatives have been found
to have the normal cystatin C genes (Table l)
(Jonsdottir
et al.,
unpublished research).
The two diagnostic methods have been shown
to have a sensitivity and specificity of 100% (16,
18 ).
This type of hereditary cerebral hernorrhage
(HCCAA) can now be added to the list ofdiseases
diagnosable by the methods of molecular gene–
tics.
TABLE l
Individuals Screened for the HCCAA-Causing Mutation in the Cystatin C Gene by Southem Blot
Analysis or the PCR-Based Procedure
Number of individuals
HCCAA patients
At-risk relatives
Healthy spouses
Unrelated indviduals
Total
Without mutation
o
48•
11
97
156
• Included is one prenatal diagnosis
20
With mutation
Total
26
26
11
59
o
11
o
97
37
193
Klinisk kemi i Norden 2, 1993
