Partial and complete trisomy 14 mosaicism: clinical follow-up, cytogenetic and molecular analysis

Background: Trisomy 14 mosaicism is a rare chromosomal abnormality. It is associated with multiple congenital anomalies. We report a 15 year-old female with an unusual karyotype with three cell lines: 47,XX,+mar/47,XX,+14/ 46,XX. At six months old she had short stature, cleft palate, hyperpigmented linear spots in arms and legs and developmental delay. At present, she has mild facial dysmorphism and moderate mental retardation. Methods: Cytogenetic analysis was performed in peripheral blood lymphocytes and in the light and dark skin following standard methods. DNAarray – Oligo 180 k was carried out using Agilent Technologies and FISH analysis was accomplished using DNA BACs probes to confirm the result obtained by DNAarray. Methylation-Specific PCR (MS-PCR) of the MEG3 promoter and microsatellite analysis were performed. Results: Microarray analysis confirmed partial trisomy 14 mosaicism; the marker chromosome was found to be from chromosome 14, the result was confirmed with FISH. Methylation (14q32.3) and microsatellite (14q11-14q32.33) analysis were carried out and UPD was discarded. The global result was: mos 47,XX,+del(14)(q11.2)[45]/47,XX,+14 [10]/46,XX[45]. Conclusions: This is a unique case because of the coexistence of two abnormal cell lines, including one with +14 and another with +del(14)(q11.2). To our knowledge, only three patients have been reported with trisomy 14 and another abnormal cell line. The array analysis identified the marker chromosome and characterized the breakpoint. The del(14)(q11.2) does not seem to be related to any particular phenotypic characteristic of the patient; the clinical features of our patient observed until now, can be attributed to trisomy 14 mosaicism. Nevertheless, we cannot discard the manifestation of new symptoms related to her karyotype in the future.