The Cretan type of non-deletional hereditary persistence of fetal hemoglobin [Aγ–158C→T] results from two independent gene conversion events

Abstract

We report a new type of non-deletional hereditary persistence of fetal hemoglobin that is due to a C-->T transition at position -158, relative to the Cap site of the human Agamma-globin gene. This mutation was identified in three unrelated adult cases presenting slightly elevated levels of fetal hemoglobin (Hb F), i.e. 2.9-5.1%, and normal hematological indices. Our sequencing results, from both polymerase chain reaction-amplified and subcloned DNA fragments, indicate that the A gamma -158C-->T mutation occurred by two independent gene conversion events in the three cases studied. In addition, hematological and molecular data, including restriction fragment length polymorphism haplotyping in the beta-globin gene cluster, extended haplotype analysis inside the gamma-globin gene region and routine analysis of three tandem repeat loci (D1S80, 3'HVR/apoB and F8vWf), led us to conclude that the A gamma -158C-->T mutation in one of the three cases occurred recently in the parental germ line (P=99.47%), representing the first example of a de novo gene conversion event identified in humans.

A?-haplotypes: A new group of genetic markers for thalassemic mutations inside the 5? regulatory region of the human A?-globin gene

“…Transient expression studies were carried out in K562 erythroleukemia cells transfected by electroporation (250 V, 960 F) with 20 g of A␥-pCAT constructs and the amount of CAT protein was measured using the Quan-T-CAT kit (Amersham, UK), as described [6].…”

“…Of these, the G␥-158 C→T variation is consistently linked with increased G␥-globin chain in cis [3]. In addition, an even increasing number of nucleotide substitutions, located within other cis-regulatory sequences 5Ј or 3Ј of the ␥-globin genes including the locus control region (LCR) hypersensitive sites (HS) [4], has been well studied over the last years, using both in vitro and in vivo assays [5][6][7].…”

Human trypsinogens in the pancreas and in cancer

“…The presence of several donor sequences in genes T6, T7, T8 and T9 for Arg122His, Asn29Ile and Ala16Val mutations, respectively, is strongly suggestive of these mutations being caused by gene conversion events. Furthermore, chilike and palindromic sequences are frequently observed in the vicinity of potentially converted gene fragments (Collier et al, 1993, Giordano et al, 1997, Patrinos et al, 1998. Such sequences are also found in the 3' and/or 5' boundaries of the Arg122His, Asn29Ile and Ala16Val mutations Feréc, 2000a, Chen andFeréc, 2000b).…”

Hellenic National Mutation Database: a prototype database for mutations leading to inherited disorders in the Hellenic population

“…2). Disorders include: congenital adrenal hyperplasia (CYP21 deficiency) [DracopoulouVabouli et al, 2001]; a-thalassemia ; b-thalassemia [Kollia et al, 1992] (Manoussos Papadakis et al, unpublished results); cystic fibrosis [Nunes et al, 1991;Tzetis et al, 2001;Kanavakis et al, 2003]; Connexin26 (GJB2) nonsyndromic sensorineural deafness [Antoniadi et al, 1999[Antoniadi et al, , 2000Pampanos et al, 2002] [Konstantopoulos et al, 2003]; G6PD deficiency [Menounos et al, 2000[Menounos et al, , 2003; hereditary hemochromatosis [Papazoglou et al, 2003]; HPFH [Patrinos et al, 1998;Papadakis et al, 2002], familial hypercholesterolemia [Dedoussis et al, 2004], phenylketonuria [Traeger-Synodinos et al, 1994], and Wilson disease [Loudianos et al, 1998[Loudianos et al, , 2000.…”