Variable levels of mosaicism for trisomy 21 in a non‐immune hydropic infant with chylothorax

Abstract

We report the first case of mosaic trisomy 21 with non-immune hydrops fetalis and bilateral chylothoraces. Prenatal fetal blood karyotype analysis of 15 fetal cells revealed a 46,XX karyotype. Aggressive prenatal management, including fetal thoracocentesis and pleuro-amniotic shunt, was performed. A clinical phenotype of Down syndrome was apparent after the gross oedema had subsided. Subsequent chromosome study of neonatal blood lymphocytes showed mosaic trisomy 21 with 23 per cent trisomic cells. Review of the initial fetal blood sample identified trisomy in 5 per cent of 134 cells. Follow-up study at five months showed no trisomy 21 in 100 cells. This case illustrates the variable levels of mosaicism manifest in the peripheral blood of an infant with obvious Down syndrome phenotype, and the limitation of cytogenetic analysis of peripheral lymphocytes alone in prenatal and postnatal detection of low levels of mosaicism.

Thrombolysis for Central Venous Occlusion Causing Bilateral Chylothorax in a Patient with Down Syndrome

“…Subsequently, several cases of trisomy 21 have been reported with bilateral chylothorax and fetal hydrops detected antenatally in the absence of cardiac defects (11,12). Although the association of trisomy 21 with congenital chylothorax is well described, the exact cause is unclear.…”

Rare case of massive congenital bilateral chylothorax in a hydropic fetus with true mosaicism 47,XXX/46,XX

“…Other rare cases have been occasionally reported, including trisomy 13, partial 12q trisomy and 4‐p syndrome . To our knowledge, in the online literature available, just two cases have been reported so far in association with mosaicism, one with a 46,XY/46,XX and another one with 46,XX/47,XX+21. This latter case was characterized by variable levels of mosaicism and, eventually, a final genetic diagnosis of Down syndrome during infancy was made.…”

Nonimmune Hydrops Fetalis Due to Generalized Lymphatic Dysplasia in an Infant with Robertsonian Trisomy 21

“…Conversely, control of chyle flow with peritoneovenous shunt may be appreciated. [5][6][7] Aneuploidy syndromes (trisomy 21, 1,2 Turner syndrome) and Noonan syndrome [8][9][10] are often associated with chylothorax and/or chylous ascites. Lymphedema occasionally is accompanied by Turner syndrome and Noonan syndrome.…”

“…drops fetalis occasionally develop in infants with trisomy 21. 1,2 Most patients with neonatal chylothorax are managed with the conservative or surgical treatment, and more than half of them achieve spontaneous remission. 3 During the last 10 years, we experienced five cases of chylous effusions in trisomy 21 infants that were diagnosed antenatally.…”