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Strong variable clinical presentation in 3 patients with 7q terminal deletion
S G Frints1, C T Schrander-Stumpel, E F Schoenmakers
1Division of Molecular Cell Biology/Genetics, Maastricht University, The Netherlands.
Genetic Counseling (Geneva, Switzerland)
|April 29, 1998
Summary
Microdeletions in chromosome 7q36 are linked to holoprosencephaly (HPE) spectrum disorders. These deletions impact genes like SHH, crucial for brain development, even with subtle HPE signs.
Area of Science:
- Genetics
- Developmental Biology
- Neuroscience
Background:
- Terminal deletions of chromosome 7q can lead to complex developmental abnormalities.
- Holoprosencephaly (HPE) is a spectrum of brain malformations resulting from incomplete forebrain cleavage.
- The 7q36 region is known to harbor genes critical for embryonic development.
Observation:
- Three patients presented with de novo 7q36 terminal deletions and varying degrees of microcephaly.
- Clinical features included partial corpus callosum hypoplasia, growth retardation, facial dysmorphism, and a single maxillary central incisor.
- Two patients exhibited minimal forms of holoprosencephaly (HPE).
Findings:
- Fluorescence in situ hybridization (FISH) confirmed 7q36.1-->qter deletions in all three patients.
- The deleted region encompassed the Sonic hedgehog (SHH) gene, a key HPE-associated gene.
- Other deleted genes important for brain development included En2, HOX1, and HTR5A.
Implications:
- 7q36 microdeletion analysis is crucial for diagnosing patients with subtle HPE features.
- These findings highlight the role of 7q36 genes in brain patterning and midline development.
- Early identification of 7q36 deletions can guide clinical management and genetic counseling.