Abstract
BackgroundSegmental duplication of the long arm of chromosome 14 (14q) has commonly been reported to affect the proximal segment of 14q, while distal duplication is a rare condition and often associated with segmental monosomy of other chromosomes.Case presentationWe report the clinical and genetic characterization of a 4-year-old male patient with 14q32.3-qter trisomy resulting from an adjacent segregation of a paternal reciprocal translocation (14;21)(q32.1;p12). The child shows minor facial anomalies, severe developmental delay, growth retardation, and a history of congenital hypothyroidism and neonatal transitory hyperglycemic crises.ConclusionsTo the best of our knowledge, only 15 other cases of segmental 14q trisomy were documented. We compared molecularly defined cases to identify a minimal common duplicated region and to find genes with a hypothetical role in the phenotype. The presented case supports the previous suggestion of a pure “distal 14q partial duplication” and underlines the clinical variability.
Highlights
ConclusionsTo the best of our knowledge, only 15 other cases of segmental 14q trisomy were documented
Segmental duplication of the long arm of chromosome 14 (14q) has commonly been reported to affect the proximal segment of 14q, while distal duplication is a rare condition and often associated with segmental monosomy of other chromosomes.Case presentation: We report the clinical and genetic characterization of a 4-year-old male patient with 14q32.3qter trisomy resulting from an adjacent segregation of a paternal reciprocal translocation (14;21)(q32.1;p12)
Sequences with a high level of homology, dispersed within and inter chromosomes, are the basis of an incorrect pairing followed by recombination; this mechanism is known as Non Allelic Homologous Recombination (NAHR)
Summary
Our observation support the existence of a “distal 14q duplication syndrome” characterized by facial dysmorphisms (high/prominent forehead, hypertelorism, downslanted palpebral fissures, wide flattened nasal bridge, broad mouth, thin upper lip with exaggerated Cupid’s bow, micrognathia), hyptonia, growth retardation and developmental delay which may be severe. Further cases will clarify the incidence of major malformations. We found that congenital heart defects are the most frequent major malformations (4 out of 11 patients), while CNS anomaly and kidney hypoplasia, both observed only in our patient, seem to be rare. Thyroid involvement will deserve specific attention in patients affected by triple copy of 14q terminal region, in order to understand its real incidence and pathophysiology.
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