2008 Barcelona - European Society of Human Genetics

Molecular and biochemical basis of disease
in the erythroid cells of the bone marrow . Biochemical features of EPP
include increased protoporphyrin levels in erythrocytes, plasma, feces,
and bile . Clinical manifestations of the disease are characterized by
cutaneous photosensitivity, which almost always appears in childhood
and includes burning, itching, swelling, and redness in sun-exposed
areas . Hepatic failure occurs in some patients (about 1-10% of EPP
patients) which may necessitate liver transplantation . The gene encoding
human FECH is localized on chromosome 18q21 .3, and spans
over 45kb with eleven exons . The cDNA encodes a protein containing
423 amino acids, and the enzyme exists as a homodimer of 86 kDa .
Each subunit contains residues 65-423 and one [2Fe-2S] cluster .
Mutational analyses of the FECH gene revealed a novel unpublished
mutation in the FECH gene in a patient from Czech Republic with EPP:
a G→A transition at position 84 in exon 2. This point mutation alters to
a tryptophan to a stop codon (W28X) . The amino acid tryptophan at
position 28 is located in a mitochondrial targeting sequence spanning
amino acid residues 1-62 that is removed during proteolytic processing
. Analyses were carried out on seven members of proband’s family;
all persons, except one, are asymptomatic carriers .
Supported by grants # 1M0520 and MSM 0021 620806 from Ministry
of Education, Youth and Sports of Czech Republic .
P05.040
Identification of the molecular defects in Turkish FHL patients
assigned to Perforin and munc13-4 genes
G. Balta 1 , H. Okur 1 , N. Akarsu 1 , S. Berrak 2 , S. Unal 1 , A. Gurgey 1 ;
1 Hacettepe University, Ankara, Turkey, 2 Marmara University, Istanbul, Turkey.
Familial Hemophagocytic Lymphohistiocytosis (FHL) is a rare autosomal
recessive, if untreated, fatal disorder of early childhood . The
purpose of this study is to evaluate the genetic defects underlying
clinical phenotypes observed in Turkish patients with this disorder . The
subjects of this study were a total of 79 FHL patients (52M/27F) from
74 unrelated families (consanguinity:62, family history:31) . Linkage
analysis used for subtyping the patients to FHL type II revealed homozygosity
or consanguineous common alleles in 19 of these families . Direct
sequencing of Perforin gene led to the identification of 5 different
sequence changes in 12 families . Six patients had nonsense W374X
mutation in homozygous state except one who was coming from a
non-consanguineous family . Two patients had G149S, one V50M, two
A91V and one novel A523D homozygous missense changes . Mutations
in this gene account for about 16% of Turkish FHL patients in this
study . On the other hand, 20 families were found to show either homozygosity
or consanguineous common alleles for Munc13-4 gene in
the linkage analysis . These patients were screened for mutations in 32
exons of Munc13-4 gene by SSCP/heterodublex analysis . Sequencing
the aberrant bands, thus far, led to the identification of 3 different
homozygous mutations in 3 unrelated patients who were coming from
consanguineous families . A frameshift (627delT) mutation was detected
in a female patient who also had heterozygous A91V mutation in
Perforin gene while nonsense (R1065X) and novel missense (R414C)
mutations were found in 2 male patients . This study was supported by
TUBITAK (Project No: 105S386; SBAG-3193) .
P05.041
six new mutations in UNC D gene in Russian patients with
familial hemophagocytic lymphohistiocytosis (FHL)
N. Poltavets 1 , M. Maschan 2 , A. Polyakov 1 , G. Novichkova 2 , A. Maschan 2 ;
1 Research Centre for Medical Genetics, Moscow, Russian Federation, 2 Federal
Research Clinical Center for pediatric hematology, oncology and immunology,
Moscow, Russian Federation.
FHL is a rare autosomal recessive disorder of immune regulatory pathways
characterized by a defect in natural killer cell function . UNC13D
gene codes a protein involved in vesicle priming function and its mutations
have been shown to cause FHL. We have examined five Russian
unrelated patients with FHL in age ranged from 1 to 5 years ( two familial
and three sporadic cases) . We have investigated DNA samples
for mutation in UNC13D gene coding area by direct sequencing . All
our patients were found to be compound heterozygotes, carring two
mutations (c .2343 del 2344-2347 / c .3037 ins G; c .3037 ins G / c .3173
T>C ( p .1058 Leu > Pro); c .627 del T / c .1828 ins A; c .322-1 G>A (CD
042833) / c .3037 ins G; c .2215 del 2216-2239 / c .2343 del 2344-2347
) .Only one mutation c .322-1 G>A (CD 042833) has been previously
reported, and six others are new . The mutation c .2343 del 2344-2347
has been observed in two chromosomes and c .3037 ins G in three
chromosomes . According to our results we propose that there might be
“hot points” in UNC13D gene, where mutations are found with higher
frequency .
P05.042
Familial hypercholesterolemia: experience from a portuguese
genetic department
I. M. Gaspar 1 , A. Gaspar 2 , S. Martins 3 , A. Mourato 4 , M. Antunes 3 , L. Sousa 4 ,
A. Cabral 5 , D. Gaspar 6 , O. Moldovan 7 , M. Simao 7 , I. Gomes 7 , H. Santos 7 , C.
Alves 8 , S. Silva 8 , A. Medeiros 8 , M. Bourbon 8 ;
1 Centro Hospitalar Lisboa Ocidental, Lisboa, Portugal, 2 Consulta de Prevenção
de Doenças Cardiovasculares, Serviço de Pediatria - Hospital de Santa Maria,
Lisboa, Portugal, 3 Consulta de Prevenção de Doenças Cardiovasculares,
Serviço de Pediatria Hospital de Santa Maria, Lisboa, Portugal, 4 Consulta de
Prevenção de Doenças Cardiovasculares, Serviço de Pediatria Hospital de
Santa Maria, Lisboa, Portugal, 5 Consulta de Prevenção de Doenças Cardiovasculares,
Serviço de Pediatria Hospital de Santa Maria, Lisboa, Portugal, 6 Centro
Estudos - Ministerio de Educação, Lisboa, Portugal, 7 Serviço de Genética
Medica, Hospital de Santa Maria, Lisboa, Portugal, 8 Unidade de Investigação
Cardiovascular, Instituto Nacional de Saúde, Lisboa, Portugal.
Familial Hypercholesterolemia (FH) is an autosomal dominant disorder,
usually caused by mutations on the low density lipoprotein receptor
gene (LDLR), the gene encoding apolipoprotein B (APOB) or
Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) which is associated
with premature atherosclerosis and coronary heart disease
(CHD) .
OBJECTIVES: Clinical and molecular characterization of patients and
their children with family history of premature CHD and abnormal lipid
profile.
MATERIAL AND METODS: a clinical questionnaire from the “Portuguese
FH Study” was completed, characterized their lipid profile and
study mutations in LDLR, APOB and PCSK9 genes .
RESULTS: We observed 163 persons, 111 adults and 52 children in
56 families . 13 patients with CHD were younger than 50 years of age .
The mean total cholesterol was 264, 41 mg/dL and 294,09 mg/dL and
mean LDL-cholesterol was 189 .87 mg/dL for and 206 .1 mg/dL for children
and adults respectively . All families received counseling regarding
lifestyle and dietary modifications. After dietary or pharmacological
therapy, mean cholesterol was 222,14 mg/dL and 238,6 mg/dL and
mean LDL-cholesterol was 148 .25 mg/dL and 160 .6 mg/dL for children
and adults respectively . Molecular study of the LDLR gene was
performed in 56 families, and a mutation was found in 23 families . No
mutations were identified in APOB or PCSK9 genes.
CONCLUSION: Molecular study of FH patients offers the possibility
of identification of the mutation in relatives at risk for premature atherosclerosis.
Early diagnosis allows earlier lifestyle modifications and
dietary or pharmacological intervention in mortality and morbidity .
P05.043
Functional analysis of potencial splice site mutations by Rt-PcR
of LDLR mRNA isolated from fresh blood mononuclear cells
A. C. Alves, M. A. Duarte, A. M. Medeiros, L. Marques, V. Francisco, M. Bourbon;
Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal.
Familial hypercholesterolemia (FH) is an autosomal dominant disorder
associated with high risk of coronary heart disease . FH is caused
mainly by inherited defects on the Low Density Lipoprotein Receptor
gene (LDLR) resulting in increased circulating LDL cholesterol . Of the
many different LDLR mutations found in FH patients worldwide, about
6 % of single base substitutions are located near or within introns
and are predicted to result in exon skipping, retention of an intron or
activation of cryptic sites during mRNA splicing . Ten such mutations,
four of them novel, were found in the “Portuguese FH Study”, and
those whose effect on splicing was untested have been investigated
by RT-PCR of LDLR mRNA isolated from fresh blood mononuclear
cells . Four of these variants (313+6 T>C, 1060+1G>A, c .2389G>T
(p .V776L), 2547+1G>A) caused exon skipping, and one caused retention
of an intron (c .1359-5C>G),while two others (c .2140+5 G>A and
c .1061-8T>C) had no apparent effect . Variants in two patients lost to
follow-up could not be tested experimentally, but they almost certainly
affect splicing because they disrupt the invariant AG or GT in acceptor
(818-2A>G) or donor (1845+1delG) spice sites . These mutations rep-