A de novo 1.4-Mb deletion at 21q22.11 in a boy with developmental delay.

[monosomy 21]

Monosomy 21 is a very rare chromosomal abnormality . At least 45 patients with partial deletion involving 21 q 11 have been reported . Here , we report a Japanese boy who presented with pre- and postnatal growth delays , psychomotor developmental delay , microcephaly , and iris coloboma . Cytogenetic analysis revealed a de novo 1 .4 -Mb deletion at 21 q 22 .11 containing 19 protein-coding RefSeq genes . We compared the clinical phenotypes between the present patient and 16 previously reported patients with a deleted region associated with postnatal growth delay and psychomotor developmental delay . Interestingly , ITSN 1 was the only gene deleted or disrupted in all cases ; this gene is known to be associated with intellectual disability . Microcephaly and brain structural abnormalities including polymicrogyria and agenesis /hypoplasia of the corpus callosum may also result from haploinsufficiency of ITSN 1 , highlighting its clinical significance for the neurological features of patients with monosomy 21 .

Diseases
Validation

Diseases presenting "brain structural abnormalities including polymicrogyria and agenesis" symptom

monosomy 21

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