2008 Barcelona - European Society of Human Genetics

Molecular and biochemical basis of disease
P05.209
A novel frame-shift mutation of the EDA gene in a spanish family
with X-linked hypohidrotic ectodermal dysplasia
M. Núñez Lozano 1 , S. Ciria Abad 1 , J. Cañueto Álvarez 2 , M. I. Zafra Cobo 2 , M.
Morán Estefanía 2 , A. Santos-Briz Terrón 2 , P. Unamuno Pérez 2 , R. González
Sarmiento 1 ;
1 Unidad de Medicina Molecular-Departamento de Medicina, Universidad de
Salamanca, Salamanca, Spain, 2 Departamento de Dermatología, Hospital
Universitario de Salamanca, Salamanca, Spain.
X-linked hypohidrotic ectodermal dysplasia (XLHED) is characterized
by defects in the development of ectodermal structures as sweat
glands, hair and teeth . Mutations in EDA gene, which codes for ectopasin-A,
cause alterations in the protein and seems to be responsible
for this disorder . In the present study, we analyse, by PCR, heteroduplex
analysis and automatic sequencing, the full coding region and the
exon-intron boundaries of the EDA gene in DNA from peripheral blood
of one Spanish family with XLHED .
We found an alteration in the EDA gene in two members of the studied
family . This alteration consists in a duplication of 2bp (c .974-975ins-
GA) in the 5 exon that produces a change in the DNA sequence of collagen
like domain rich in Gly-X-Y motifs . This domain is important for
multimerization of the protein . Furthermore this duplication produces a
truncation of the last exon that codes for a part of a TNF-like domain,
which can affect the NF-κB and c-Jun kinase pathway.
The two affected members of the family show remarkable phenotypic
characteristics on skin, teeth, eyebrows, lips and head hear, but aggravated
in one of them . This phenomenon is explained by inheriting
of the mutation and epigenetics mechanisms of anticipation of the disease
across generations .
This results show a novel mutation in the EDA gene in a Spanish family
with XLHED syndrome which introduces a new reading frameshift and
a premature stop codon . This extends our knowledge of pathogenic
mutations in EDA gene .
P05.210
X-linked juvenile Retinoschisis (XLRs) in spanish patients:
common ancestries, hot spots and incomplete penetrance
R. Riveiro-Alvarez1,2 , M. Trujillo-Tiebas1,2 , M. Garcia-Hoyos1,2 , D. Diego-Alvarez1,2
, D. Cantalapiedra1,2 , E. Vallespin1,2 , J. Aguirre-Lamban1,2 , A. Avila-Fernandez1,2
, A. Gimenez1,2 , C. Ramos1,2 , C. Ayuso1,2 ;
1 2 Fundacion Jimenez Diaz, Madrid, Spain, Centro de Investigación Biomédica
en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain.
Purpose: X-linked juvenile Retinoschisis (XLRS) is one of the most
common causes of juvenile macular degeneration in males, characterised
by mycrocystic changes, splitting within the inner retinal layer
(“schisis”) and presence of vitreous veils . The aim was to describe the
genotype-phenotype correlation in Spanish XLRS families with mutations
in the RS1 gene .
Methods: The study was performed in 31 Spanish XLRS families,
comprising 46 affected males and two symptomatic women . Molecular
analyses included direct sequencing, haplotype construction and determination
of the X inactivation pattern .
Results: 18 different RS1 mutations were identified; eight of them were
novel ones . These new changes included missense (p .Gln154Arg,
p .Leu137Pro, p .Glu215Val, p .Arg197Ser, p .Pro192Leu, p .His207Asp),
nonsense (p .Gln80Ter) and frameshift substitutions (p .Thr138fsX) . 2
out of 31 “de novo” mutational events were detected . The most common
mutation (p .Gln154Arg; 6/18) presented a common haplotype .
The symptomatic women showed a normal X inactivation pattern . Interestingly,
a healthy male presenting the p .Arg209His mutation was
identified.
Conclusions: A prevalent mutation in Spanish XLRS patients
(p.Gln154Arg) has been first reported in this work and presented a
common origin . The frequency of “de novo” mutations was 6%, which
mainly rise in CG dinucleotides (hot spots) . Further analyses showed
that the retinal affectation in both women could be due to mutations in
another gene . Nevertheless, the possibility of incomplete penetrance
for RS1 variants or a gain-of-function alteration in a different interacting
gene might be suspected . Despite the mutation spectrum is large
and the phenotype variable, there was no correlation between mutation
type and severity of disease .
P05.211
Hierarchical analysis of 28 Y-chromosome sNP’s in the
population of the Republic of macedonia
P. Noveski, S. Trivodalieva, G. D. Efremov, D. Plaseska-Karanfilska;
Macedonian Academy of Sciences and Arts, Research Centre for Genetic
Engineering and Biotechnology, Skopje, The former Yugoslav Republic of
Macedonia.
Analysis of Y-chromosome haplogroups, defined by single nucleotide
polymorphisms (SNP’s), has become a standard approach for studying
the origin of human populations and measuring the variability among
them . Furthermore, Y-SNP’s represent a new forensic tool, because
their population specificity may allow to determine the origin of any
male sample of interest for forensic purposes . The aim of this study
was to develop a strategy for rapid, simple and inexpensive Y-chromosome
SNP’s typing in the population of R . Macedonia . We have studied
a total of 343 DNA male samples; 211 Macedonians, 111 Albanians
and 21 of other ethnic origin (Roma, Serbs and Turks) . Methodology
included multiplex PCR and single nucleotide extension reaction by
SNaPshot multiplex kit . The set of 28 markers has been grouped in
5 multiplexes in order to determine the most frequent haplogroups
using only 1 or 2 multiplexes . Twenty different Y haplogroups were
determined among 343 male DNA samples. The finding that five haplogroups
(E3b1, I1b1, J2b1a, R1a and R1b) comprise more than 70%
of the Y chromosomes is consistent with the typical European Y chromosome
gene pool . The distribution of the Y-haplogroups differs between
Macedonians and Albanians . The most common Y haplogroup
among Macedonians is I1b1 (27 .5%), followed by three haplogroups
present with similar frequencies E3b1 (15 .6%), R1a (14 .2%) and R1b
(11 .4%) . Among Albanians the most frequent Y haplogroup is E3b1
(28 .8%), followed by R1b (18 .0%), J2b1a (13 .5%) and R1a (12 .6%) .
P05.212
Elucidating the molecular function of ZFYVE27 (Protrudin)
K. Pantakani D.V., T. Khromov, J. Wolter, G. Tomasik, H. Hühn, A. U. Mannan;
Instiute of Human Genetics, University of Göttingen, Göttingen, Germany.
ZFYVE27 is a member of the FYVE-finger family of proteins. The
FYVE-finger domain is suggested to be responsible for endosomal localization
of these proteins and the majority of the FYVE-finger proteins
serve as regulators of endocytic membrane trafficking. ZFYVE27 was
identified as a spastin interacting protein and previously, we characterized
its interaction with spastin in mammalian cells . More importantly,
we identified a German family in which mutation in ZFYVE27 causes
autosomal dominant form of hereditary spastic paraplegia (HSP) . A
comprehensive expression analysis of ZFYVE27 in mouse revealed
a high level of expression primarily in the HSP affected tissues such
as brain, cerebellum and spinal cord . Immunohistochemical analysis
of tissue sections from various subdivisions of brain and spinal cord
showed expression in both cell soma and axons of the motor-neurons
. To elucidate the molecular function of ZFYVE27 in vivo, we are
generating a loss of function mouse model by knockout strategy .Conceivably
the phenotype of these mouse models might mimic the pathological
features of HSP, therefore will provide us with a valuable model
system to study the underlying cause for HSP etiology .
P05.213
Pitfalls of mapping a large turkish consanguineous family with
vertical monilethrix inheritance
F. Celep 1 , A. Uzumcu 2 , F. M. Sonmez 3 , O. Uyguner 2 , Y. Isik Balci 4 , S. Bahadir 5 ,
A. Karaguzel 1 ;
1 Karadeniz Technical University, Faculty of Medicine, Department Medical Biology
and Genetics, Trabzon, Turkey, 2 Istanbul University, Istanbul Medical Faculty,
Department of Medical Genetics, Istanbul, Turkey, 3 Karadeniz Technical
University, Faculty of Medicine, Department of Pediatrics Neurology, Trabzon,
Turkey, 4 Pamukkale University Faculty of Medicine, Department of Pediatrics
Haematology, Denizli, Turkey, 5 Karadeniz Technical University, Faculty of Medicine,
Department of Dermatology, Trabzon, Turkey.
Monilethrix, a rare autosomal dominant disease characterized by hair
fragility and follicular hyperkeratosis, is caused by mutations in three
type II hair cortex keratins . The human keratin family comprises 54
members, 28 type I and 26 type II . The phenotype shows variable
penetrance and results in hair fragility and patchy dystrophic alopecia
. In our study, Monilethrix was diagnosed on the basis of clinical
characteristics and microscopic examination in a family with 11 affected
members . Haplotype analysis was performed by three Simple