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Uniparental disomy of chromosome 14 (UPD(14)) results in one of two distinct abnormal phenotypes depending upon the parent of origin.1 The discordance between the maternal and paternal UPD(14) phenotypes may result from overexpression and/or underexpression of one or more imprinted genes located on chromosome 14q. A cluster of imprinted genes has been identified and localised to 14q32.2–5 However, it is unknown whether the altered expression of these genes results in any of the phenotypic features associated with maternal and paternal UPD(14). To refine the candidate imprinted region, it would be useful to identify cases of segmental UPD with clinical features associated with paternal or maternal UPD(14). We recently reported the first case of segmental paternal isodisomy of chromosome 14.6 In addition, there are two reported cases of segmental maternal UPD(14).7,8 We recently had the opportunity to re-evaluate the patient reported by Martin et al.7
Key points
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We performed comprehensive microsatellite marker analysis on a previously reported case of segmental maternal uniparental disomy for chromosome 14.
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Of the 103 markers tested, only one suggested maternal uniparental disomy. Other informative markers within the same linkage group indicated biparental inheritance of chromosome 14.
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We therefore conclude that this most likely represents a mutation of a polymorphic marker, rather than uniparental disomy.
CASE REPORT
The patient was admitted to the Texas Children’s Hospital General Clinical Research Center after parental informed consent for participation in our Baylor College of Medicine Institutional Review Board approved research protocol. On physical examination, her weight and length were normal (50th centile). She showed relative macrocephaly, with head circumference at the 97th centile. Her only dysmorphic features were a high forehead and a pointed chin. She had normal hands and feet and did not have scoliosis, joint laxity, or any evidence …