Protein and DNA analysis for the prenatal diagnosis of alpha2-laminin-deficient congenital muscular dystrophy.
Congenital muscular dystrophies (CMD) are characterized by neonatal hypotonia and/or artrogriposis associated with a dystrophic muscle biopsy. The CMD1A form is caused by a deficiency of the alpha2 chain of laminin 2 (LAMA2 gene at 6q2), a protein present in the basal lamina of muscle fibers, in Schwann cells, epidermis, and in fetal trophoblastic tissue. This allows its study for prenatal diagnosis in the chorionic villous (CV), which was performed in a family with one deceased affected CMD1A child. Immunohistochemical analysis of the CV using antibodies against the C- and N-terminal domains of the alpha2-laminin protein showed a normal positive labeling for both antibodies in the "at-risk" CV, which did not differ from the normal control CV. The integrity of the CV membrane was confirmed through the analysis with antibodies against alpha1, beta1, and gamma1 laminins. DNA study using markers flanking the 6q2 region showed that the affected patient and the "at-risk" fetus did not share the same haplotype. Therefore, the fetus was considered normal through both methodologies, which was confirmed after the birth of a clinically normal male baby. As the LAMA2 gene is very large and the spectrum of mutations causing disease is wide, the analysis of the protein in muscle biopsy has been largely used for the diagnosis. Besides, the possibility to detect it in the chorionic villous, mainly using positive markers, also offers a powerful tool for prenatal diagnosis.
Department of Biology, Human Genome Research Center, São Paulo, Brazil.
Lydia U
LU
Yamamoto
Thomas R
TR
Gollop
Nadyr F
NF
Naccache
Rita C M
RC
Pavanello
Edmar
E
Zanoteli
Mayana
M
Zatz
Mariz
M
Vainzof
D000911:Antibodies, Monoclonal; D015193:Chorionic Villi Sampling; D005260:Female; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D007797:Laminin / Q000032:analysis* / Q000172:deficiency* / Q000276:immunology; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D018482:Muscle, Skeletal / Q000502:physiology*; D009136:Muscular Dystrophies / Q000151:congenital / Q000175:diagnosis* / Q000235:genetics
D000911:Antibodies, Monoclonal; D007797:Laminin; C102645:laminin alpha 2