The localization of the autosomal dominant polycystic kidney disease locus (PKD1) within an array of anonymous polymorphic DNA sequences on chromosome 16 band p13 was determined by multipoint mapping.
Linkage studies have been carried out using two probes (3'HVR and 24-1) linked to ADPKD on locus PKD1 and two probes (alpha 1-PstI and BamH-I/EcoRI-zeta 2 fragment) allowing detection of alpha-thalassemia with either a 3.7-kb deletion or a 4.2-kb deletion.
The polymorphic DNA probe VK5B (D16S94) was mapped by genetic linkage in families from the Centre d'Etude de Polymorphisme Humain (CEPH) as being in the same interval as the autosomal dominant adult polycystic kidney disease locus (PKD1).
We studied 17 families with autosomal dominant polycystic kidney disease to compare presymptomatic diagnosis by ultrasonography with diagnosis by genetic-linkage studies and to relate clinical variation of the disease to whether the PKD1 mutation was implicated.
Sixty-eight individuals from six Italian families in which autosomal dominant polycystic kidney disease (ADPKD) is segregating, were typed in DNA polymorphisms linked to the PKD1 locus on chromosome 16.
The most likely order of six of the probes from the telomere is palpha3'HVR.64 at the designated locus D16S85, CRI-0327 at D16S63, CRI-090 at D16S45, CRI-0129 at D16S56, CRI-0133 at D16S58, and CRI-0136 at D16S60, with the PKD1 locus for ADPKD between D16S85 and D16S63.
Since no cytogenetic abnormalities have been found in association with ADPKD, flanking genetic markers have been required to define an interval--the PKD1 region--that contains the PKD1 gene.
The mean (SE) age of onset of ESRD is 56.3 (1.8) years for persons with the PKD1 form of ADPKD, and 68.7 (1.7) years for affected members of families in which ADPKD is not co-inherited with PKD1 markers (P = 0.01).
Although most mutations causing ADPKD in European populations have been mapped to the PKD1 locus on chromosome 16, some of them appear to be unlinked to this locus.
We have mainly used 3 highly polymorphic DNA markers, 3'HVR (D16S85), 16AC2.5 (D16S291) and SM7 (D16S283), flanking the PKD1 region on chromosome 16p13.3 to establish linkage status in seven Icelandic families with autosomal dominant polycystic kidney disease (ADPKD).
Assuming that a clinic population represents the most severe forms of a disease and non PKD-1 is a less aggressive phenotype, the degree of genetic heterogeneity for APKD in the population may well be much greater than at present suggested.
Genetic linkage studies were carried out in 11 relatives (4 with ADPKD), and on fetal DNA obtained from cultured amniocytes, using 8 flanking DNA markers tightly linked to the PKD1 locus on chromosome 16p, and a DNA marker linked to another putative ADPKD locus on chromosome 2p.
Furthermore, when flanking markers for the second ADPKD gene are used in conjunction with flanking markers for PKD1, the accuracy of the diagnosis of the subtype of ADPKD present in any particular family will be enhanced.