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"Essentially pure" partial trisomy (6)(p23-->pter) in two brothers due to maternal t(6;17)(p23;p13.3)
B Röthlisberger1, D Kotzot, H E Gnehm
1Institut für Medizinische Genetik, Universität Zürich, Zürich, Switzerland.
Insights
Two brothers with partial trisomy 6p, a genetic condition, exhibited growth issues and distinct facial features. This specific chromosomal abnormality, dup(6)(p23-->pter), defines a unique clinical presentation.
Area of Science:
- Genetics
- Human Genetics
- Clinical Genetics
Background:
- Partial trisomy 6p can result from various chromosomal rearrangements.
- Maternal translocations are a known cause of partial trisomy.
Observation:
- Two brothers presented with low birth weight, growth retardation, microcephaly, minor facial anomalies, and mental retardation.
- Fluorescent in situ hybridization (FISH) confirmed a small additional deletion on 17p13, suggesting the phenotype was primarily due to partial trisomy 6p.
Findings:
- The clinical phenotype in these brothers is attributed to pure partial trisomy 6p (dup(6)(p23-->pter)).
- Comparison with literature cases delineated a specific phenotype for dup(6)(p23-->pter), including low birth weight, growth retardation, microcephaly, blepharophimosis, blepharoptosis, microstomia, and abnormal ears.
Implications:
- This study helps delineate the specific clinical features associated with dup(6)(p23-->pter).
- Understanding this phenotype aids in genetic counseling and diagnosis for similar cases.
- Further research can refine genotype-phenotype correlations in partial trisomy 6p.
Abstract:
We report on two brothers with low birth weight, growth retardation, microcephaly, minor facial anomalies, mental retardation, and trisomy (6)(p23-->pter) due to a maternal t(6;17)(p23;p13.3). As demonstrated by fluorescent in situ hybridisation (FISH) with the Miller-Dieker cosmid probe (D17S379) and with a subtelomeric probe (D17S34) the additional deletion on 17p13 is very small, and therefore, the phenotype of these two boys is most likely the result of essentially pure partial trisomy 6p. Comparison of the clinical findings with those of ten cases from the literature of dup(6p) with a breakpoint in or more distal to 6p23 allows delineation of a specific phenotype of dup(6)(p23-->pter) characterized by low birth weight, growth retardation, microcephaly, and blepharophimosis, blepharoptosis, microstomia, and abnormal ears.