OBJECTIVEAngelman syndrome (AS) is a neurodevelopmental genetic disorder that maps to 15q11-13. The primary phenotypes are attributable to loss of expression of imprinted UBE3A gene within this region which can arise by means of a number of mechanisms. The purpose of this study was to make a genetic diagnosis and to analyze the clinical features in suspected patients with AS.

METHODA total of 17 cases were diagnosed clinically as AS including 7 males and 10 females. The age at the time of diagnosis ranged from 8 months to 5 years. Genetic diagnosis was made by methylation-specific PCR (MS-PCR), linkage analysis by short tandem repeat (STR) and chromosome karyotype analysis. According to the international diagnostic criteria of AS, the related characteristic clinical features of the AS patients with deletion of 15q11-13 were analyzed and summarized.

RESULTDeletion of 15q11-13 was confirmed by genetic diagnosis in 17 AS patients. No abnormal findings were observed when they were born. Developmental delay in movement, speech impairments and happy disposition were observed in 100% (17/17) AS patients. And the severe speech deficit was much easier and more obvious to observe than movement. About 80% (14/17) - 90% (15/17) AS patients presented frequent clinical characteristics, such as seizures and abnormal EEG. However, microcephaly could only be observed in 35% (6/17) AS patients. Regarding the associated findings of AS, 41% (7/17) - 77% (13/17) AS patients could be observed with flat occiput/occipital groove, prognathia, wide mouth, wide-spaced teeth, frequent drooling, excessive mouth behaviors, hypopigmented skin, light hair compared to parents, flexed arm position during ambulation and sleep disorder etc. These features occurred at a higher frequency in those patients of > 2 years old group than that of < 2 years old group.

CONCLUSIONThe testing strategies of MS-PCR and STR linkage analysis combined with chromosome karyotype analysis were appropriate to the molecular genetic diagnosis of AS. In our analysis of clinical features, there was a lower rate of small head circumference (HC) in 35% patients compared with 80% patients in Caucasian with microcephaly, which might be attributable to the phenotypic heterogeneity in different races. And the birth history, movement and speech development and main clinical features of the Chinese AS patients were consistent with those of other studies. Clinical analysis in patients of different age groups showed that findings associated with AS would be more easily observed with the age increasing. Genetic diagnosis should be performed in clinically suspected AS patients.