Paternal UPD15: further genetic and clinical studies in four Angelman syndrome patients.
Among 25 patients diagnosed with Angelman syndrome, we detected 21 with deletion and 4 with paternal uniparental disomy (UPD), 2 isodisomies originating by postzygotic error, and 1 MII nondisjunction event. The diagnosis was obtained by molecular techniques, including methylation pattern analysis of exon 1 of SNRPN and microsatellite analysis of loci within and outside the 15q11-q13 region. Most manifestations present in deletion patients are those previously reported. Comparing the clinical data from our and published UPD patients with those with deletions we observed the following: the age of diagnosis is higher in UPD group (average 7 3/12 years), microcephaly is more frequent among deletion patients, UPD children start walking earlier (average age 2 9/12 years), whereas in deletion patients the average is 4 (1/2) years, epilepsy started later in UPD patients (average 5 10/12 years) than in deletion patients (average 1 11/12 years), weight above the 75th centile is reported mainly in UPD patients, complete absence of speech is more common in the deleted (88.9%) than in the UPD patients because half of the children are able to say few words. Thus, besides the abnormalities already described, the UPD patients have somewhat better verbal development, a weight above the 75th centile, and OFC in the upper normal range.
Fridman
C
C
Department of Biology, Institute of Bioscience, University of São Paulo, Brazil. cfridman@ib.usp.br
Varela
M C
MC
Kok
F
F
Diament
A
A
Koiffmann
C P
CP
D017204:Angelman Syndrome / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D005220:Fathers; D005260:Female; D018392:Genomic Imprinting; D006801:Humans; D007223:Infant; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics