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Intellectual disability v2.847 DYNC1I2 Konstantinos Varvagiannis gene: DYNC1I2 was added
gene: DYNC1I2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DYNC1I2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: DYNC1I2 were set to 31079899
Phenotypes for gene: DYNC1I2 were set to Microcephaly; Intellectual disability; Abnormality of nervous system morphology; Abnormality of head or neck
Penetrance for gene: DYNC1I2 were set to Complete
Review for gene: DYNC1I2 was set to AMBER
Added comment: Ansar et al. (2019 - PMID: 31079899) report on five individuals from 3 families, with biallelic likely pathogenic DYNC1I2 variants.

The phenotype consisted of microcephaly, intellectual disability, cerebral malformations and suggestive facial features. 2/5 individuals, from different families presented seizures.

Affected individuals from a consanguineous Pakistani family were homozygous for a splicing variant (c.607+1G>A - RNA was unavailable for further studies). One individual from a futher family was compound heterozygous for a missense variant (c.740A>G or p.Tyr247Cys) and a 374 kb deletion encompassing DYNC1I2 as well as 3 other genes (DCAF17, CYBRD1, SLC25A12). Another individual was found to harbor c.740A>G (p.Tyr247Cys) in trans with c.868C>T (p.Gln290*). [NM_001378.2 used as reference].

DYNC1I2 encodes Dynein Cytoplasmic 1 intermediate chain 2, a component of the cytoplasmic dynein 1 complex. This complex is involved in retrograde cargo transport within the cytoplasmic microtubule network. Emerging evidence suggests a critical role of this complex in neurodevelopment and homeostasis (PMIDs cited by the authors: 25374356, 28395088). Mutations in other genes encoding components of the complex (principally DYNC1H1) give rise to neurological disorders, some of which with ID as a principal feature (eg. Mental retardation, autosomal dominant 13 - MIM 614563).

In zebrafish, DYNC1I2 has 2 orthologs - dync1i2a and dync1i2b. The former is suggested to be the functionally relevant DYNC1I2 ortholog as CRISPR-Cas9 dync1i2a disruption and/or suppression with morpholinos resulted in altered craniofacial patterning and reduction in head size (similar to the microcephaly phenotype reported in affected individuals).

In vivo complementation studies suggested a loss of function effect for the p.Tyr247Cys variant, similar to the p.Gln290* one.

Evidence is provided for a role of increased apoptosis, probably secondary to altered cell cycle progression (prolonged mitosis due to abnormal spindle morphology), to explain the reduced head size/microcephaly phenotype.

There is no associated phenotype in OMIM/G2P.

As a result, DYNC1I2 could be considered for inclusion in the ID panel probably as amber (ID reported for 5 individuals from 3 families, severity of ID not specified for all, eg. fam. 2 for whom the deletion was also spanning other genes which might contribute to the phenotype).
Sources: Literature
Intellectual disability v2.468 DYNC1H1 Louise Daugherty Source Victorian Clinical Genetics Services was added to DYNC1H1.
Intellectual disability DYNC1H1 BRIDGE consortium edited their review of DYNC1H1
Intellectual disability DYNC1H1 BRIDGE consortium edited their review of DYNC1H1
Intellectual disability DYNC1H1 BRIDGE consortium reviewed DYNC1H1