2008 Barcelona - European Society of Human Genetics

Clinical genetics
gene . Most of these mutations are point mutation and large deletions
are not common . A considerable number of deletions of variable size
and position that involve the β-globin gene cluster on chromosome 11
are associated with the clinical entities of δβ thalassemia.
δβ-thalassemia normally results from deletion involving either δ- and
β-globin genes or the Aγ-,δ- and β-globin genes.
In this study six individual from two families were investigated because
of low MCV and MCH, high HbF and normal HbA2 referred from primary
health care (PHC) centers to our lab for further investigations .
PCR amplification was performed for known deletions causing δβ-thalassemia
and HPFH by gap-PCR methods .
In Hb electrophoresis an extra band was appeared . Molecular analysis
showed that the two affected individuals from one of the families are
homozygous for Hb Lepore and the remaining four cases carry Hb
Lepore in heterozygous form . One of the affected cases was transfusion
dependent . Genotype Phenotype correlation was compatible with
cases presented in giobin gene server database . Hb Lepore usually
causes mild anemia with microcytosis and hypochromia in the heterozygote
(beta+-thal) . The molecular basis of this Hb variant is a (aprox)
7 kb deletion from the distal part of δ-globin gene to proximal region
of β-globin gene.
P01.020
Hb F malta i in association with Hb F sardegna and Hb Valletta;
triple heterozygosity at the human Gγ, Aγ and β globin genes
suggest interplay between flanking regulatory sequences in the
developmental control of globin gene switching
J. Borg, R. Galdies, W. Cassar, C. A. Scerri, A. E. Felice;
Laboratory of Molecular Genetics, Faculty of Medicine, University of Malta, and
Section of Molecular Genetics, Mater Dei Hospital., Msida, Malta.
Here we document for the first time data on unique families from Malta
in whom heterozygosities at the Gγ, Aγ, and β globin genes have segregated
among families to produce probands that were heterozygotes
at the three major non-α genes, such that the six globin products could
be separated and quantified. 136 newborn were found with Hb F Malta
I on isoelectricfocusing . Further testing by reverse phase LC showed
heterozygosities at the β globin gene (βA /β Valletta ) and the Aγ globin
gene (AγI / AγT) confirmed by DNA sequencing in 8. The probands
were genotyped at the Xmn I site in the 5’ Gγ promoter that is known
to be associated with increased γ globin gene output in anaemic adults
and the (AT) X T Y polymorphism in the 5’ β globin gene region known
to down-regulate β globin gene expression subject to BP1 binding.
Seven were Xmn I negative and (AT) 7 T 7 and with [Gγ FMaltaI + AγI] / [Gγ0
+ AγT] = 0.90 that was significantly different from the other triple heterozygote
with Xmn I negative and (AT) 9 T 5 and [Gγ FMaltaI + AγI] / [Gγ0
+ AγT] = 0.80 (p < 0.037). The data suggested interplay between the
Xmn I and the (AT) X T Y sites around a fulcrum of the Y / PYR sequences
close to the pseudo-β sequences and that acted to control globin gene
expression differentially between neonates and adults .
P01.021
A case of Hb torino in an italian family
C. Lodrini, M. Garatti, D. A. Coviello, A. Biasi, C. Melles, R. Salvi, C. Domzelli,
C. Curcio;
Fondazione IRCCS, Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena,
Milan, Italy.
Alfa thalassemias are haematologic diseases arising from more than
80 different genetic alterations, affecting one or both copies of the duplicated
α globin genes (α1 and α2) located in 16p13.3.
Although most causative alterations are large genomic deletions, at
least 48 non-deletional point mutations have also been reported so
far .
We report here a case of Hb Torino found in an Italian family: the proband
is a young boy aged six, who presented haematological parameters
similar to α thalassemia.
The α-globin2-specific PCR product were amplified. Direct sequencing
of amplified PCR product showed the presence of Hb Torino (Cod43
TTC->GTC, Phe->Val) in both cromosomes in the proband . Since Hb
Torino was detected in the homozygous state and it is quite a rare variant
we decided to extend the analysis to patient’s parents .
The father resulted to be an heterozygous carrier for Hb Torino, while
the mother had a 3 .7 deletion in the heterozygous state . Then we concluded
that proband had the Hb Torino in one chromosome and α 3.7
deletion in the other chromosome .
The correct diagnosis, improved after the case history, included the
presence of the base substitution causing Hb Torino and the α 3.7
deletion, both in the heterozygous state .
Our data underline that the molecular screening of α thalassemia, associated
to the family study are useful to better characterize the genotypes
involved and perform an appropriate genetic counselling .
P01.022
Hemoglobin Lepore chromosome in serbia: a report of a novel
Lepore haplotype
S. Pavlovic1 , B. Zukic1 , M. Stojiljkovic1 , L. Perisic1 , J. Jovanovic1 , L. Dokmanovic2
, D. Janic2 ;
1Institute of Molecular Genetics and Genetic Engineering, Belgrade, Serbia,
2University Children’s Hospital, Belgrade, Serbia.
Hemoglobin (Hb) Lepore is a thalassemic hemoglobin variant characterized
by normal alpha-globin and fused delta/beta-globin chains .
Heterozygosity for this abnormality resembles a beta-thalassemia
trait, while homozygotes have a severe form of beta-thalassemia .
Hb Lepore-Boston Washington (BW) is the most common type of Hb
Lepore . The chromosomal background heterogeneity has been assessed
in Hb Lepore BW chromosomes, suggesting its multicentric
origin . Molecular characterization of Serbian patients with thalassemia
syndromes in last ten years revealed that Hb Lepore is the most
common cause of thalassemia phenotype in the population of Serbia
(25%) . Three thalassemia major patients (compound heterozygotes
for Hb Lepore and beta-thalassemia mutation) and 36 heterozygous
Hb Lepore carriers were characterized in 15 unrelated families . Molecular
detection of Hb Lepore gen was carried out by gap-PCR analysis
. Sequencing analysis showed that all Hb Lepore genes were of
BW type . Moreover, they were all associated with the same intragenic
beta-globin gene polymorphisms, framework 2 . Additionally, we have
studied beta-globin gene cluster haplotypes and their association with
Hb Lepore gene in Serbian population by PCR-RFLP analysis of 8
polymorphic sites (Hinc II/epsilon, Xmn I/5’Ggamma, Hind III/Ggamma,
Hind III/Agamma, Hinc II/pseudobeta, Hinc II/3’pseudobeta, Ava
II/beta, BamHI/3’beta) . Haplotype analysis revealed a novel haplotype
associated with Hb Lepore BW gene (+--+--+-) . The same haplotype
was found in healthy individuals of Serbian descent . The high frequency
of Hb Lepore BW hemoglobin variant in Serbian population, the
homogeneity of Hb Lepore BW haplotype, as well as its uniqueness,
suggest that it most probably originated in Serbia .
P01.023
control of thalassemia in iran, a National success story
S. Zeinali1 , A. Samavat2 ;
1 2 Pasteur Institute of Iran, Tehran, Islamic Republic of Iran, Center for Disease
Control, Ministry of Health, Tehran, Islamic Republic of Iran.
Thalassemia is the most prevalent single gene disorder in Iran and
most part of the world . Now more than 18000 patients live in Iran .
Prenatal diagnosis of thalassemia started, in Iran, as early as 1991 by
sending samples abroad and as early as 1994 it became feasible to
do it in Iran . National Program for Prevention of Thalassemia has been
started in 1997 and the religious FATWA was given in 1996 to allow
prenatal diagnosis (PND) . From 1997 every couple who wants to get
married is tested for being a carrier of thalassemia . If both partners are
carriers or are in doubt of their carrier status are referred to one of several
prenatal diagnosis centers throughout the country . Regular visits
and inspections are carried out to ensure the best performance . Every
PND done is reported to the Genetics Office at CDC.
There are more than 10 medical genetics labs in Iran and most of them
active in doing PND for thalassemia . Most of these laboratories have
been organized as being a network and families are referred to one of
these labs via the Health Centers throughout country .
In our medical genetics lab at Kawsar Genomics and Biotechnology
Complex we have performed more than 2000 PNDs . We have also
analyzed more than 4000 samples referred to us for thalassemia . Only
one mistake has been made out of 2000 PNDs which may indicate
application of best QA and QC .