[Prenatal diagnosis of spinal muscular atrophy (SMA) -- indications, restrictions, interpretation of results].
BACKGROUND
Proximal spinal muscular atrophy of childhood and adolescence (SMA) is a genetic autosomal recessive disease. Caused in 96.5% by deletion in the SMN1 gene. Owing to the homogeneity of the molecular defect. Secondary prophylaxis can readily be offered to families at risk of SMA.


METHODS
Prenatal diagnosis of SMA was carried out in a group of 50 families. Which were divided into two subgroups: with high and relatively low genetic risk of SMA. In all, 55 prenatal tests were performed in the period 1998-2003.


RESULTS
In the first group including 45 families at high genetic risk, 9 of the 50 tests were positive (18%). The diagnosis of SMA was tentative in 7 cases from this group and it was based only on the clinical picture (the affected children are not alive, therefore DNA samples are not available). Prenatal examination in 1 of these 7 families showed the SMA genotype. In the second subgroup including 5 families with relatively low genetic risk of SMA in none of the studies was there a biallelic deletion of exon 7 in the SMNI gene. Mainly parents of children with a severe form of SMA and having no healthy offspring asked for prenatal examination (73% of the families).


CONCLUSIONS
Prenatal diagnosis could be offered to families even if the diagnosis of SMA was not genetically verified. The negative result should he then interpreted individually. Until the carrier test will not he introduced to routine procedures. prenatal diagnosis can be also offered to families at relatively low risk of SMA.
Jedrzejowska
Maria
M
Instytut Medycyny Doświadczalnej i Klinicznej, Polska Akademia Nauk, Pawińskiego 5, 02-106 Warszawa, Poland.
Zimowski
Janusz
J
Wiszniewski
Wojciech
W
Sielska
Danuta
D
Bal
Jerzy
J
Mazurczak
Tadeusz
T
Hausmanowa-Petrusewicz
Irena
I
Zaremba
Jacek
J
D000328:Adult; D002648:Child; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics* / Q000378:metabolism; D005192:Family Health; D005260:Female; D005817:Genetic Counseling / Q000379:methods; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing / Q000379:methods; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics*; D011044:Poland; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D016601:RNA-Binding Proteins / Q000235:genetics*; D012189:Retrospective Studies; D055532:SMN Complex Proteins; D014897:Spinal Muscular Atrophies of Childhood / Q000175:diagnosis* / Q000235:genetics*; D055533:Survival of Motor Neuron 1 Protein
D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; D055533:Survival of Motor Neuron 1 Protein