Mosaic trisomy 12 diagnosed in a female patient: clinical features, genetic analysis, and review of the literature

Hainz, Daniela; Krüger, M.; Reber, Daniela; Mehnert, Karl; Brunet, Theresa; Lederer, Gaby; Langer-Freitag, Sabine; Hoefele, Julia

doi:10.1007/s12519-021-00438-9

Cited by 5 publications

(6 citation statements)

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“…Particularly, patient 1 showed unique eye alterations as bilateral distichiasis and triple rows of upper lashes; patient 2 showed redundant skin in the back of his neck, and patient 3 presented with hypertelorism and telecanthus. All these alterations are not common features in patients previously described in the literature (Table 2 ) [ 8 ]. Because a clinical hallmark of facial dysmorphism has not yet been described for patients with mosaic trisomy 12, the definition of this entity as “Mosaic Trisomy 12 Syndrome” has not been possible [ 6 , 7 , 15 , 17 ].…”

Section: Discussionmentioning

confidence: 66%

“…Mosaic trisomy 12 remains as a rare finding in live births. Until now, only twenty-one patients have been reported [ 8 ]. Most cases have been detected prenatally (32 cases) [ 25 – 27 ].…”

Section: Discussionmentioning

confidence: 99%

“…Most cases have been detected prenatally (32 cases) [ 25 – 27 ]. Common clinical features such as developmental delay, dysmorphic facial features, musculoskeletal deformities, congenital heart defects, and pigmentary mosaicism have been described [ 8 ]. However, it is known that the clinical manifestations associated with chromosomal mosaic alterations depend on the timing of the mosaicism-inducing event, the specific type of alteration and the affected cell, the level of mosaicism and the distribution of abnormal cells in different tissues [ 5 , 18 , 21 ].…”

Section: Discussionmentioning

confidence: 99%

“…Until now, only 4/13 patients previously reported with cytogenetic analysis in PB, showed trisomy 12 mosaicism in this tissue [ 3 , 4 , 6 , 13 ], and in 5/5 patients in whom the trisomy 12 was analyzed by interphase FISH [ 6 – 9 , 18 ]. Although the detection of trisomy 12 mosaicism in lymphocytes analyzing a large number of cells turns out to be efficient [ 43 ], it also has its downsides, such as: 1) The presence of mosaic restricted to specific tissues (e.g., skin); 2) PB or skin cell culturing (growth disadvantage of trisomy 12 cell lines) and 3) PB culturing with the use of phytohemagglutinin [ 6 – 8 ]. To avoid these problems, we emphasize the importance of looking the mosaic in other tissues such as skin, or using molecular techniques that do not require cell culturing, such as FISH and/or arrayCGH [ 5 , 7 ].…”

Section: Discussionmentioning

confidence: 99%

“…Postnatally mosaic trisomy for chromosome 12 is considered a rare finding [ 2 ] and to our knowledge, there are only twenty-one reported cases diagnosed with mosaic trisomy 12 after birth [ 3 – 18 ]. At phenotypic level, mosaic trisomy 12 includes patients with an apparently normal phenotype to patients with short stature, hypotonia, microcephaly, developmental delay, dysmorphic facial features such as epicanthal folds, broad nasal bridge, and low-set rotated ears, congenital heart defects, digital alterations and pigmentary mosaicism [ 3 , 8 , 17 – 19 ].…”

Section: Introductionmentioning

confidence: 99%

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Pigmentary mosaicism as a recurrent clinical manifestation in three new patients with mosaic trisomy 12 diagnosed postnatally: cases report and literature review

et al. 2022

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Background To date, only twenty-one cases diagnosed postnatally with mosaic trisomy 12 have been reported. The most frequent phenotypic manifestations are developmental delay, dysmorphic facial features, congenital heart defects, digital alterations, and pigmentary disorders. In the present report, detailed clinical and genetic profiles of three unrelated new patients with mosaic trisomy 12 are described and compared with previously reported cases. Case presentation In the present report, we include the clinical, cytogenetic, and molecular description of three Mexican patients diagnosed postnatally with mosaic trisomy 12. At phenotypic level, the three patients present with developmental delay, dysmorphic facial features, congenital heart defects and skin pigmentary anomalies. Particularly, patient 1 showed unique eye alterations as bilateral distichiasis, triple rows of upper lashes, and digital abnormalities. In patient 2 redundant skin, severe hearing loss, and hypotonia were observed, and patient 3 presented with hypertelorism and telecanthus. Hyperpigmentation with disseminated pigmentary anomalies is a common trait in all of them. The cytogenetic study was carried out under the strict criteria of analysis, screening 50–100 metaphases from three different tissues, showing trisomy 12 mosaicism in at least one of the three different tissues analyzed. With SNParray, the presence of low-level mosaic copy number variants not previously detected by cytogenetics, and uniparental disomy of chromosome 12, was excluded. STR markers allowed to confirm the absence of uniparental disomy as well as to know the parental origin of supernumerary chromosome 12. Conclusions The detailed clinical, cytogenetic, and molecular description of these three new patients, contributes with relevant information to delineate more accurately a group of patients that show a heterogeneous phenotype, although sharing the same chromosomal alteration. The possibility of detecting mosaic trisomy 12 is directly associated with the sensitivity of the methodology applied to reveal the low-level chromosomal mosaicism, as well as with the possibility to perform the analysis in a suitable tissue.

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