Distinctive Phenotypic Abnormalities Associated with Submicroscopic 21q22 Deletion Including DYRK1A

Area of Science:

• Genetics
• Developmental Biology
• Neurology

Background:

• Partial monosomy 21 is associated with variable phenotypes depending on deletion size and location.
• Previous reports highlight the complexity of defining specific syndromes within chromosome 21 deletions.

Purpose of the Study:

• To characterize a specific microdeletion syndrome at 21q22.1-q22.2.
• To identify a recognizable phenotype associated with deletions in this locus, including the DYRK1A gene.

Main Methods:

• Case study of two patients with overlapping 21q22.1-q22.2 microdeletions.
• Clinical phenotyping including neurodevelopmental assessment and brain MRI.
• Microarray analysis to define deletion boundaries and gene content.
• Literature review of overlapping deletions involving the DYRK1A gene.

Main Results:

• Both patients presented with severe psychomotor delay, behavioral issues, microcephaly, feeding difficulties, and characteristic facial features.
• Brain MRI revealed cerebral atrophy, widened ventricles, and thin corpus callosum.
• Microarray analysis identified a shared 2.5 Mb deletion in 21q22.1-q22.2, encompassing DYRK1A but excluding RUNX1.

Conclusions:

• The 21q22.1-q22.2 microdeletion, particularly involving DYRK1A, results in a recognizable and severe phenotype.
• This study refines the understanding of genotype-phenotype correlations in chromosome 21 microdeletion syndromes.
• Further research is needed to identify other contributing genes in this critical region.