A de novo 1.4-Mb deletion at 21q22.11 in a boy with developmental delay.
Monosomy 21 is a very rare chromosomal abnormality. At least 45 patients with partial deletion involving 21q11 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 21q22.11 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, ITSN1 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 ITSN1, highlighting its clinical significance for the neurological features of patients with monosomy 21.
Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan; Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
Ryoko
R
Fukai
Yoko
Y
Hiraki
Gen
G
Nishimura
Mitsuko
M
Nakashima
Yoshinori
Y
Tsurusaki
Hirotomo
H
Saitsu
Naomichi
N
Matsumoto
Noriko
N
Miyake
D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics; D002872:Chromosome Deletion; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics; D002658:Developmental Disabilities / Q000235:genetics*; D006801:Humans; D007223:Infant; D008297:Male; D010641:Phenotype
D033942:Adaptor Proteins, Vesicular Transport; C485568:ITSN1 protein, human
21q22.11 deletion; ITSN1; copy number analysis; developmental delay; fluorescence in situ hybridization (FISH)