Molecular mapping of a translocation breakpoint at 14q13 in a patient with mirror-image polydactyly of hands and feet
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N Matsumoto1, H Ohashi, R Kato
1Department of Human Genetics, Nagasaki University School of Medicine, Japan. f0932@cc.nagasaki-u.ac.jp
Abstract:
Mirror hands and feet (MIM, 135750) is a rare congenital anomaly, and mirror-image polydactyly is considered to be a variant of mirror hands and feet. To our knowledge, seven patients with the disorder have been reported in the literature. Parent-to-child transmission was reported in two families, which may indicate a single-gene defect inherited in an autosomal dominant fashion. We had previously encountered a boy with mirror-image polydactyly whose karyotype showed 46,XY,t(2;14) (p23.3;q13) de novo. We hypothesized that at least one of the putative genes responsible for the determination of an anterior-posterior limb pattern is disrupted by a translocation breakpoint. In this study, we identified a yeast artificial chromosome clone spanning a translocation breakpoint at 14q13, and the breakpoint was confirmed to be located between two loci, AFM200ZH4 and D14S306, within a genetic distance of 0.6 cM.
Insights
Mirror hands and feet is a rare congenital anomaly. This study identified a translocation breakpoint at 14q13 in a patient, suggesting a gene disruption involved in limb pattern development.
Area of Science:
- Genetics
- Developmental Biology
- Medical Genetics
Background:
- Mirror hands and feet (MIM, 135750) is a rare congenital anomaly.
- Mirror-image polydactyly is a known variant of this condition.
- Previous reports suggest autosomal dominant inheritance in some families.
Purpose of the Study:
- To investigate the genetic basis of mirror-image polydactyly.
- To identify genes disrupted by chromosomal abnormalities in affected individuals.
- To explore the role of specific genes in limb pattern determination.
Main Methods:
- Karyotyping of a patient with mirror-image polydactyly.
- Identification of a translocation breakpoint using yeast artificial chromosome cloning.
- Fine genetic mapping of the translocation breakpoint.
Main Results:
- A de novo translocation t(2;14)(p23.3;q13) was identified in a patient.
- The translocation breakpoint at 14q13 was localized between AFM200ZH4 and D14S306.
- This breakpoint is within a genetic distance of 0.6 cM.
Conclusions:
- The identified translocation breakpoint may disrupt genes critical for anterior-posterior limb patterning.
- This finding provides a potential genetic explanation for mirror-image polydactyly in this patient.
- Further investigation is warranted to identify the specific gene(s) involved.