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Classical lissencephaly syndromes: does the face reflect the brain?
J E Allanson1, D H Ledbetter, W B Dobyns
1Children's Hospital of Eastern Ontario and University of Ottawa, Canada.
Journal of Medical Genetics
|December 1, 1998
Summary
Miller-Dieker syndrome (MDS) and isolated lissencephaly sequence (ILS) share similar facial features in young children. Subtle qualitative facial differences, like forehead shape and lip thickness, may distinguish MDS from ILS.
Area of Science:
- Genetics
- Pediatrics
- Clinical Dysmorphology
Background:
- Miller-Dieker syndrome (MDS) and isolated lissencephaly sequence (ILS) are linked to classical lissencephaly and LIS1 gene mutations on chromosome 17p.
- Traditionally, MDS is differentiated from ILS by a distinct facial phenotype, including a tall, furrowed forehead and a long, wide, thick upper lip.
- Objective anthropometric measurements have not been extensively used to compare these conditions.
Purpose of the Study:
- To compare objective facial pattern profiles between children with Miller-Dieker syndrome (MDS) and isolated lissencephaly sequence (ILS).
- To identify potential quantitative discriminators between MDS and ILS, particularly in early childhood.
- To assess the reliability of qualitative facial features in distinguishing between MDS and ILS.
Main Methods:
- Anthropometric measurements were taken from five children with MDS and 25 children and adolescents with ILS.
- Z-score (standard deviation score) pattern profiles were generated and compared between the two groups.
- Statistical analysis, including correlation coefficients, was used to evaluate the similarity of facial patterns.
Main Results:
- Patients with ILS exhibited reduced head circumference, a round head, a wide and flat face, a broad nose, and widely spaced eyes.
- A striking similarity in pattern profiles was observed between ILS and MDS patients aged 6 months to 4 years (correlation coefficient = 0.812, p<0.001).
- Distinguishing features in MDS included brachycephaly, a slightly wider face, and a significantly shorter nose compared to ILS.
Conclusions:
- Objective facial pattern profiles show significant overlap between MDS and ILS in early childhood, challenging traditional diagnostic distinctions.
- Qualitative facial features, such as a tall, furrowed forehead and a markedly thickened, inverted upper lip, remain crucial for differentiating MDS from ILS.
- Further research into quantitative anthropometric analysis may refine diagnostic criteria for lissencephaly subtypes.