2009 Vienna - European Society of Human Genetics
2009 Vienna - European Society of Human Genetics
2009 Vienna - European Society of Human Genetics
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Metabolic disorders<br />
a role for SOS1, in the pathogenesis <strong>of</strong> IH, in cooperation with other<br />
insulin pathway genes.<br />
P13.28<br />
Bulgarian metabolomic aproach for diagnosis <strong>of</strong> inherited<br />
Organic Acidurias<br />
M. B. Ivanova, I. Sinigerska, R. Vazharova, I. Bradinova, I. Kremensky;<br />
National Genetic Laboratory, S<strong>of</strong>ia, Bulgaria.<br />
Organic acidurias are clinically important heterogeneous group <strong>of</strong> rare<br />
inherited disorders with total frequency about 1:5-6 000 newborns. Because<br />
<strong>of</strong> the unspecific clinic the diagnosis requires the application<br />
<strong>of</strong> many highly specialized methods and comprehensive approach.<br />
Metabolomic approach (extensive quality investigation <strong>of</strong> the metabolome)<br />
is the most widely used approach for this purpose.<br />
In the National Genetic Laboratory a metabolomic approach for diagnosis<br />
<strong>of</strong> inherited organic acidurias was developed and introduced.<br />
The approach includes the next stages: urine qualitative target urine<br />
analysis <strong>of</strong> some metabolites, GC/MS urine organic acid pr<strong>of</strong>ile, plasma<br />
amino acids and DNA analysis.<br />
The main analytical techniques are High-effective liquid chromatography<br />
(HPLC) and Gas chromatography - mass spectrometry (GC /<br />
MS).<br />
More than 1500 high risk patients were investigated by metabolomic<br />
approach. A total <strong>of</strong> 126 patients (8.8%) were diagnosed and classified<br />
into eleven basic organic acid disorder groups: defects <strong>of</strong> the aromatic<br />
aminoacid metabolism -13; propionate and methylmalonate metabolism<br />
- 8; branched chain aminoacid metabolism - 13; mitochondrial fatty acid<br />
oxidation - 14; pyrimidine metabolism -1; γ- glutamyl cycle - 2; dibasic<br />
aminoacid metabolism - 2; lactic aciduria -38; glycolysis and Krebs cycle<br />
- 8; urea cycle - 21; miscellaneous disorders - 5;. The diagnostically<br />
informative metabolite pr<strong>of</strong>iles are detected for each disease.<br />
Our results can be assessed as a reasonably good and completely<br />
comparable to the data <strong>of</strong> the leading <strong>European</strong> genetic centers.<br />
Results indicate that the application <strong>of</strong> a metabolomic approach is a<br />
useful and reliable algorithm for diagnosis <strong>of</strong> inherited metabolic diseases.<br />
P13.29<br />
Phenotype <strong>of</strong> LAt2 knockout mice<br />
M. Espino Guarch 1 , S. Bodoy Salvans 2 , R. Sillué Bayarri 1,3 , G. Colell Dinares 1 ,<br />
M. Font Llitjós 1,3 , M. Palacín Prieto 4,5 , V. Nunes Martínez 1,3,6 ;<br />
1 Centro de Genética Médica y Molecular IDIBELL, Hospitalet de Llobregat,<br />
Spain, 2 Institute for research in biomedicine, Barcelona, Spain, 3 CIBERER<br />
U730, Hospitalet de Llobregat, Spain, 4 Institute for Research in Biomedicine,<br />
Barcelona, Spain, 5 CIBERER U730, Barcelona, Spain, 6 UNIVERSIDAD DE<br />
BARCELONA - IDIBELL. Ciencias Fisiológicas II, Hospitalet de Llobregat,<br />
Spain.<br />
LAT2 (SLC7A8) is a polytopic membrane protein that after covalent<br />
association with 4F2hc (or CD98, SLC3A2) forms an heterodimeric<br />
amino acid transporter. LAT2-4F2hc induces system L transport activity<br />
in the plasma membrane <strong>of</strong> most <strong>of</strong> the epithelial tissues (kidney,<br />
intestine, brain...). LAT2-4F2hc plays a role in the vectorial trans-epithelial<br />
flux <strong>of</strong> neutral amino acid (re)absoption, particularly important<br />
for cystine.<br />
To further study the physiological relevance <strong>of</strong> LAT2 in vivo, we generated<br />
a knockout mice model from ES cells. Mice model deficient in<br />
LAT2 presents around 85% <strong>of</strong> lethality (n=200) despite there are no<br />
differences in weight and basic behavior compared to the wild type<br />
animals (studied up to 8 months <strong>of</strong> age).<br />
We also generated an antibody that allows us to check the absence<br />
<strong>of</strong> LAT2 in the majority <strong>of</strong> the tissues where it is expressed. We also<br />
confirmed the basolateral location <strong>of</strong> LAT2 in the epithelial cells by immunohistochemistry<br />
with the same antibody.<br />
In addition to these preliminary results, we are analyzing amino acid<br />
content in urine and plasma, examining the histopathology <strong>of</strong> all tissues<br />
and evaluating different behavior parameters in the knockout<br />
mice. All these studies aim to increase our understanding about the<br />
physiological role <strong>of</strong> LAT2 and its functional cooperation with TAT1 and<br />
LAT1-4F2hc, both transporters implicated in the (re)absorption in the<br />
kidney and intestine.<br />
The LAT2 knockout mice model is viable so we have generated a potential<br />
tool to improve our knowledge <strong>of</strong> LAT2 function in vivo and its<br />
role in trans-epithelial flux <strong>of</strong> amino acids.<br />
Funded by MEC (BFU2006-14600-C02-02).<br />
P13.30<br />
Progressive myoclonic epilepsy as an adult-onset manifestation<br />
<strong>of</strong> Leigh syndrome due to the m.14487t>c mutation in ND6<br />
S. Seneca 1 , B. Dermaut 2 , P. Santens 3 , L. Dom 4 , K. Smets 5 , L. Ceulemans 6 , J.<br />
Smet 3 , B. De Paepe 3 , S. Tousseyn 7 , S. Weckhuysen 8 , M. Gewillig 8 , P. Pals 9 ,<br />
P. Parizel 10 , J. De Bleecker 3 , P. Boon 3 , L. De Meirleir 1 , P. De Jonghe 11 , R. Van<br />
Coster 3 , W. Van Paesschen 12 , W. Lissens 1 , I. Liebaers 1 ;<br />
1 UZ Brussel, Brussels, Belgium, 2 University <strong>of</strong> Leuven, VIB, Leuven, Belgium,<br />
3 University Hospital Ghent, Ghent, Belgium, 4 Koningin Paola Kinderziekenhuis,<br />
Antwerp, Belgium, 5 University <strong>of</strong> Antwerp, VIB, Antwerp, Belgium, 6 Sint-Jozefkliniek,<br />
Bornem, Belgium, 7 University <strong>of</strong> Leuven, Leuven, Belgium, 8 University<br />
Hospital Gasthuisberg, Leuven, Belgium, 9 University Hospital Antwerp, Brussels,<br />
Belgium, 10 University Hospital Antwerp, Antwerp, Belgium, 11 University <strong>of</strong><br />
Antwerp, VIB, Brussels, Belgium, 12 University Hospital Gasthuisberg, Ghent,<br />
Belgium.<br />
Mitochondrial disorders <strong>of</strong> the oxidative phosphorylation (OXPHOS)<br />
system affect ~1/5000 individuals in the general population and present<br />
with a surprisingly wide range <strong>of</strong> multisystemic and neuromuscular<br />
phenotypes. The m.14487T>C mutation is a known pathogenic mtDNA<br />
mutation resulting in an amino acid substitution (p.M63V) in NADH<br />
dehydrogenase 6 (MT ND6), a complex I subunit <strong>of</strong> the mitochondrial<br />
respiratory chain. Thus far it has been found in isolated cases with infantile<br />
Leigh syndrome and progressive dystonia. We report here adult<br />
and late-onset phenotypes as it was seen in a 5-generation Belgian<br />
family with 12 affected family members. Clinical and mutation load data<br />
were available for 9 family members, while biochemical analysis <strong>of</strong> the<br />
respiratory chain was performed in 3 muscle biopsies. Heteroplasmic<br />
m.14487T>C levels (36-52 % in leukocytes, 97-99 % in muscle) were<br />
found in patients with progressive myoclonic epilepsy (PME) and dystonia<br />
or progressive hypokinetic-rigid syndrome. Patients with infantile<br />
LS were homoplasmic (99-100 % in leukocytes, 100 % in muscle).<br />
We found lower mutation loads (8-35 % in blood) in adult patients with<br />
clinical features including migraine with aura, Leber Hereditary Optic<br />
Neuropathy (LHON), sensorineural hearing loss and Diabetes<br />
mellitus type 2. Despite homoplasmic mutation loads, complex i<br />
catalytic activity was only moderately decreased in muscle tissue<br />
<strong>of</strong> these patients.<br />
conclusions: the m.14487T>C mutation resulted in a broad spectrum<br />
<strong>of</strong> phenotypes in our family. This is the first report <strong>of</strong> PME as<br />
an important neurological manifestation <strong>of</strong> an isolated mitochondrial<br />
complex I defect.<br />
P13.31<br />
Laboratory approach for biochemical diagnosis <strong>of</strong> Lysosomal<br />
storage Diseases<br />
I. Sinigerska, I. Hassanova, M. B. Ivanova, R. Vazharova, I. Bradinova, I. Kremensky;<br />
National Genetic Laboratory, S<strong>of</strong>ia, Bulgaria.<br />
Lysosomal storage diseases (LSD) comprise a group <strong>of</strong> more than<br />
40 rare diseases, most <strong>of</strong> them resulting from a specific enzyme deficiency.The<br />
diagnosis is complicated due to their clinical, biochemical<br />
and genetic heterogeinity. Definitive diagnosis, as well as prenatal<br />
diagnosis <strong>of</strong> LSD are based on a specific enzyme or DNA analysis.<br />
Quantitative and qualitative analysis <strong>of</strong> urinary metabolites facilitates<br />
differential diagnosis, pointed to the probable enzyme deficiency.<br />
Appropriate scheme <strong>of</strong> assays depending on observed clinical features<br />
has been developed in our laboratory, in order to detect rapidly and reliably<br />
27 <strong>of</strong> known LSD and to <strong>of</strong>fer a prenatal diagnosis for them .<br />
In 30 years period more than 3000 patients , suspected <strong>of</strong> having LSD<br />
have been tested according to a flowchart for biochemical diagnosis <strong>of</strong><br />
LSD. In 112 patients a pathologycal excretion <strong>of</strong> glycosaminoglycans<br />
have been found using quantitative dimethylmethyleneblue test and<br />
qualitative thin layer chromatography or electrophoresis . Enzyme assays<br />
according to abnormal GAG patterns have been performed and<br />
58 different mucoplosaccharidoses have been diagnosed.<br />
Thin layer chromat<strong>of</strong>raphy <strong>of</strong> oligocassharides has been applied to<br />
the patients with clinical features similar to MPS but with normal GAG<br />
excretion. Abnormal bands has been found in 33 cases and relevant<br />
enyme deficiency has been demonstrated.<br />
The definitive diagnosis on enzyme level has been set in 213 cases.<br />
Prenatal diagnosis has been undertaken ih 53 cases in families with