Trisomy 8 mosaicism is a rare condition with prevalence estimates in the range of 1:25000-1:50,000 births. It is a rare genetic disorder and clinically heterogeneous condition associated with a spectrum of developmental abnormalities, including intellectual disability, congenital heart defects and agenesis of corpus callosum [1,2]. Approximately 50% of these patients present with renal abnormalities [3]. We report a boy with dysmorphic features and delayed development.

A 10-year-old boy with delayed development and dysmorphic features was referred to us for cytogenetic analysis. The proband was first born child to consanguineous parents. He had short stature (height 121 cm, US: LS=0.86), dolicocephaly, broad nose with anteverted nostrils, flat tip pinnae, bilateral limited extension of elbow, restricted joint movements, bilateral comptodactyly, bilateral radial head subluxation, bilateral femoral neck coxa valga, squint, tongue tie, webbed neck and agenesis of corpus callosum. He had vestibular hypersensitivity, and fear of swings, heights and climbing of ladder. Psychological examination showed moderate sub-normality in social functioning. Radiological examination showed generalized osteopenia; electroencephalography (EEG) and thyroid function tests were normal. The cytogenetic analysis using GTG banding revealed mosaic trisomy 8 in 25% of metaphases scored. Fluorescence in situ hybridization (FISH) analysis using Vysis centromeric probe for chromosome 8 showed 59% cells with trisomy 8, and the karyotype was determined as mosaic trisomy 8 (46,XY/46,XY+8).

Trisomy 8 mosaicism occurs due to non-disjunction of chromosome 8 during mitosis in the zygote phase of fetal development. This condition is clinically heterogeneous, and it is associated with wide range of clinical abnormalities [1-4]. Our patient had additional clinical features: restricted joint movements, bilateral comptodactyly, bilateral radial head subluxation, bilateral femoral neck coxa valga, squint, tongue tie and webbed neck. Correlation of genetic abnormalities with clinical phenotype is always important to establish the syndromic diagnosis. The follow-up of mosaic trisomy 8 is essential, as it is more commonly seen in patients with acute myeloid leukemia and myelodysplastic syndrome.

1. Fineman RM, Ablow RC, Howard RO, Albright J, Breg R. Trisomy 8 mosaicism syndrome. Pediatrics. 1975;56:762-7.

2. Wisniewska M, Mazurek M. Trisomy 8 mosaicism syndrome. J Appl Genet. 2002; 43:115-8.

3. Aykut A, Cogulu O, Ozkinay F. Mosaic trisomy 8 syndrome with a novel finding of ectopic kidney. J Genet Couns. 2012;23:17-80.