J Korean Pediatr Soc.  1997 Aug;40(8):1110-1119.

Fragile X Syndrome : Clinical Characteristics and EEG Findings

• Chung HJ
• Cha KE
• Lee SH

Abstract

PURPOSE
Fragile X syndrome is an X-llinked genetic disorder and is characterized by mental retardation, learning disability, behavior disorder, and autism with typical elongated face, large ears, and macro-orchidism. Recent reports have focused attention on the EEG finding of this syndrome, which is a particular paroxysmal pattern during sleep (mono or diphasic centrotemporal spikes) and awake state (background slowing). In this study, we analyzed the clinical characteristics of fragile X syndrome patients and observed whether a particular EEG pattern is associated with this syndrome or not.
METHODS
7 cases of fragile X syndrome, diagnosed at Sowha Children's Hospital and Cha General Hospital from August 1993 to February 1995, were analyzed retrospectively in terms of typical phenotypes and clinical & EEG characteristics. The patients were diagnosed by Southern blotting and polymerase chain reaction (PCR) method.
RESULTS
1) The subjects were all male and the mean age was 5.8 years old (2Y-11Y). 2) Typical phenotype of long elongated face, macro-orchidism, large ears, and large head are noted in 2/3 of the subject. 3) Developmental delay, mental retardation, learning disability, attention deficit, hyperactivity, and autism are noted in 2/3 of the subject. 4) Seizure is noted in one case and EEG was performed in 6 cases, regardless of the presence of seizures. Abnormal findings including centrotemporal sharps and background slowing are noted in one case, each. 5) By molecular diagnostic methods including Southern blotting and PCR, 3 cases of affected male and 4 of normal transmitting male were diagnosed.
CONCLUSIONS
1) The typical phenotype of fragile X syndrome is long elongated face, macro-orchidism, large ears and large head. 2) The non-physical characteristics of fragile X syndrome are developmental delay, mental retardation, learning disability, attention deficit, hyperactivity, and autism. 3) The characteristic EEG findings of fragile X syndrome known by literature are noted in 2 among 6 cases, which means the specificity is high even though the sensitivity is low. This allows us to propose this EEG pattern as an important "marker" in the diagnosis of fragile X syndrome. However, the number of the subject is too small to conclude now. Further accumulation of cases is reguired.

Keyword

Fragile X syndrome; Phenotype; Typical EEG findings

MeSH Terms

Autistic Disorder
Blotting, Southern
Diagnosis
Ear
Electroencephalography*
Fragile X Syndrome*
Head
Hospitals, General
Humans
Intellectual Disability
Learning Disorders
Male
Pathology, Molecular
Phenotype
Polymerase Chain Reaction
Retrospective Studies
Seizures
Sensitivity and Specificity