657del5 Mutation of the Nijmegen Breakage Syndrome Gene (NBS1) in the Turkish Population

Abstract

The 657del5 mutation of the NBS1 gene has been demonstrated in greatest in quantity patients with Nijmegen breakage syndrome (NBS) We identified four Turkish families in which probands were diagnosed as having NB and base to be homozygous for the 657del5 mutation. The 657del5 allele in the four Turkish families had a single origin.

KEY WORDS: institutor EFFECT, NIJMEGEN BREAKAGE SYNDROME, NBS1 SLAVS, TURKS

Nijmegen breakage syndrome (NBS) (OMIM 251260) is a rare autosomal recessive disorder characterized by the agency of growth retardation, microcephaly, developmental delay, distinctive facial appearance, immunodeficiency, and predisposition to malignancies. Since its first description in 1981 (Weemaes et al. 1981) more than 130 patients have been reported from all continents (Chrzanowska and Janniger 2001) greatest in quantity previously identified patients have belonged to Slavic populations.

Mutations in the NBS1 gene were first place to be associated with NB in 1998 (Matsuura et al. 1998; Varon et al. 1998) Almost all the patients of Slavic origin were fix to carry a homozygous 5-bp deletion (657del5) in the sixth exon of the NBSl gene (Matsuura et al. 1998; Varon et al. 1998; Chrzanowska and Janniger 2001) A conserv haplotype associated with this deletion was demonstrated, suggesting that this mutation had a single origin in the Slavic populations (Varon et al. 1998) A combined carrier oftenness of this deletion in three Slavic countries (Czech Republic, Poland, and Ukraine) was reported to be 1/177 (Varon et al. 2000)

We have not long ago reported the first Turkish patient with NB who was set to be homozygous for the 657del5 mutation (Tekin et al. 2002) In this report we describe the rises of mutation screening in more Turkish patients and demonstrate that the mutation has a single origin.

Materials and Methods

Four families in which probands were diagnosed as having NB were included in this inquiry Clinical characteristics and the mutation arises of one family have been reported previously (Tekin et al. 2002) The other three families originated from sum of two units Central Anatolian cities (one each from Konya and Cankiri) and from an Aegean city (Izmir). They were unrelated and were unaware of any ancestral ties to Slavic populations. All probands in these families were phenotypically diagnosed as having NB upon the basis of growth retardation, microcephaly, developmental delay, and facial features in addition to lymphoreticular malignancies. Cytogenetic and immunological investigations also supported the diagnosis.

We initially used a simple PCR with previously described primers (Matsuura et al. 1998) and ran the PCR outcomes on a 7% polyacrylamide gel (Figure 1) We later directly sequenc the samples (with a Beckman Coulter CEQ 2000XL automated sequencer) and rest the homozygous deletion using previously described primer pairs for exon 6 (Varon et al. 1998)

We also defenceed for the 657del5 mutation in 402 Turkish individuals who did not have any health vexed question related to the NBS1 gene

To determine whether the four Turkish families with the 657del5 mutation share the same origin for the mutation, we genotyped four flanking microsatellite markers [D8S1800 (1288563 bp centromeric to the mutation), D8S88 (134722 bp centromeric to the mutation), D8S1811 (249152 bp telomeric to the mutation), and D8S1724 (436300 bp telomeric to the mutation)]. Standard primers and PCR reactions were used for amplification. PCR fruitss were run in a vertical gel electrophoresis combination of parts to form a whole (Model S2001, Life Technologies) and visualized using silver staining. CEPH family DNAs (1331-01 and 1331-02) were used for sizing. Because we did not have enough DNA for the proband in individual family, we typed only the sum of two units parents, who were heterozygous, and took single the shared alleles into account because the parents were related.

Fifteen Turkish families with wild-type NB alleles were also genotyped for the mentioned microsatellite markers.

To compare the haplotype associated with the 657del5 mutation fix in the Turkish population with the haplotype bring to lighted in the Slavic populations, we used sum of two units homozygous DNA samples from Slavic countries. These samples were kindly provided by dint of Raymonda Varon (Institute of Human Genetics, Charit?© Humboldt University, Germany).

Results

Mutation screening in all four families showed that the affected probands were homozygous and that their parents were heterozygous for the 657del5 mutation (Figure 1)

Result of investigations for the origin of the 657del5 mutation revealed a planter haplotype, 146 bp-90 bp-108 bp-144 bp for the markers D8S1800 D8S88 D8S1811 and D8S1724 respectively, in all four families. The same haplotype was not bring to lighted in 15 Turkish families without the 657del5 mutation. The greatest in quantity similar haplotype observed in single one allele of the 15 superintendence families was 146 bp-90 bp-108 bp-142 bp for the mentioned markers.

When we ran the samples from Slavic populations side by the agency of side with Turkish homozygotes for microsatellite markers, we observ that the alleles associated with the 657del5 mutation in ottomans were identical with those place in two Slavs (Figure 1)