In Angelman syndrome, prenatal and perinatal development typically proceeds normally. Diagnosis is based on a comprehensive clinical evaluation, a detailed family history, and the identification of characteristic findings. Genetic tests confirm the diagnosis in approximately 90% of cases. About 80% of cases are confirmed through blood tests such as DNA methylation analysis. These tests can detect deletions and uniparental disomy within the critical region associated with Angelman syndrome (specifically chromosome 15q11-q13). Methods like FISH or microarray analysis can also identify these deletions. In cases not detected by the above methods, UBE3A gene sequencing can identify mutations in an additional 11% of cases.