Objective To investigate the clinical features,
karyotype,and the
prenatal diagnosis for his
sibling of a
Chinese patient with rare
ring chromosome 20
syndrome induced
intractable epilepsy.
Methods The clinical data of the
patient diagnosed in
Peking University People's
Hospital were collected.The clinical manifestations,
chromosome karyotype were summarized.Results The proband,a boy,started to show intermittent tonic seizures or atypical absence seizures and psychomotor retardation from the age of 11 months.Several anti-
epilepsy drugs and
globulin had been tried without effect.Common
karyotype analysis and
epilepsy-related
genes analysis revealed no abnormality.However,
abnormal karyotype 46,XY,r(20)(p13q13.3) in his peripheral
blood lymphocytes was found by high resolution
chromosome karyotype analysis with 550 G-banding,and the
diagnosis of
ring chromosome 20
syndrome,type Ⅱ was confirmed.The
mother of the
patient underwent
amniocentesis at the midterm of the second
pregnancy.The cultured amniocytes
karyotypes were normal.The second
child(a boy) of the
family was 1 year old without
epilepsy and the psychomotor development was normal.Conclusions
Ring chromosome 20
syndrome is a rare
human chromosome abnormality.The
syndrome is associated with epileptic seizures,
behavior disorders and
mental retardation.Since
karyotype testing is not a routine investigation for the
patient with
epilepsy,the
diagnosis of
ring chromosome 20
syndrome is usually delayed or misdiagnosed.The
karyotype analysis should be considered for the etiological study of the
patients with
intractable epilepsy with unknown origin.