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Causal heterogeneity in isolated lissencephaly.
W B Dobyns1, E R Elias, A C Newlin
1Department of Neurology, Indiana University School of Medicine, Indianapolis.
Neurology
|July 1, 1992
Summary
Isolated lissencephaly sequence (ILS) is caused by genetic factors, including microdeletions in chromosome 17p13.3. Other causes like recessive inheritance and intrauterine issues also contribute to this severe neurodevelopmental disorder.
Area of Science:
- Genetics
- Neurology
- Developmental Biology
Background:
- Isolated lissencephaly sequence (ILS) is a severe neurodevelopmental disorder characterized by a smooth brain surface.
- Understanding the genetic and etiological basis of ILS is crucial for diagnosis and genetic counseling.
Observation:
- Clinical, cytogenetic, and molecular studies were performed on 65 patients with ILS.
- Patients presented with type I lissencephaly, severe intellectual disability, seizures, and motor impairments.
- Facial appearance was generally normal, but additional brain abnormalities were sometimes observed.
Findings:
- Microdeletions in chromosome band 17p13.3 were identified in 6 of 44 patients, confirming this region's critical role in ILS.
- Larger deletions in the same region were associated with Miller-Dieker syndrome.
- Other identified causes included a de novo translocation, autosomal recessive inheritance, intrauterine infection, and perfusion failure.
- An empiric recurrence risk of 7% was calculated for ILS cases with unknown etiology.
Implications:
- Genetic testing for 17p13.3 microdeletions should be considered in patients with ILS.
- The findings highlight the genetic heterogeneity of ILS, necessitating comprehensive diagnostic approaches.
- Accurate etiological diagnosis is vital for genetic counseling and understanding recurrence risks.