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Intellectual disability v5.290 DOHH Arina Puzriakova Phenotypes for gene: DOHH were changed from DOHH associated neurodevelopmental disorder to Neurodevelopmental disorder with microcephaly, cerebral atrophy, and visual impairment, OMIM:620066
Intellectual disability v5.288 DOHH Arina Puzriakova Tag Q4_22_MOI was removed from gene: DOHH.
Tag Q4_22_promote_green was removed from gene: DOHH.
Intellectual disability v5.286 DOHH Arina Puzriakova reviewed gene: DOHH: Rating: GREEN; Mode of pathogenicity: ; Publications: ; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v5.286 DOHH Arina Puzriakova Source NHS GMS was added to DOHH.
Source Expert Review Green was added to DOHH.
Rating Changed from Amber List (moderate evidence) to Green List (high evidence)
Intellectual disability v3.1737 DOHH Eleanor Williams Tag Q4_22_rating was removed from gene: DOHH.
Tag Q4_22_promote_green tag was added to gene: DOHH.
Intellectual disability v3.1732 DOHH Sarah Leigh Classified gene: DOHH as Amber List (moderate evidence)
Intellectual disability v3.1732 DOHH Sarah Leigh Added comment: Comment on list classification: There is enough evidence for this gene to be rated GREEN at the next major review.
Intellectual disability v3.1732 DOHH Sarah Leigh Gene: dohh has been classified as Amber List (Moderate Evidence).
Intellectual disability v3.1731 DOHH Sarah Leigh Tag Q4_22_rating tag was added to gene: DOHH.
Tag Q4_22_MOI tag was added to gene: DOHH.
Intellectual disability v3.1731 DOHH Sarah Leigh gene: DOHH was added
gene: DOHH was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DOHH was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: DOHH were set to 35858628
Phenotypes for gene: DOHH were set to DOHH associated neurodevelopmental disorder
Review for gene: DOHH was set to GREEN
Added comment: Not associated with a phenotype in OMIM, Gen2Phen or MONDO. PMID: 35858628 reports six DOHH variants in three unrelated cases of a neurodevelopmental disorder. All of these cases had intellectual disability, microcephaly and hypotonia.
Sources: Literature
Intellectual disability v2.597 DHPS Konstantinos Varvagiannis gene: DHPS was added
gene: DHPS was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DHPS was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: DHPS were set to 21389784; 21850436
Phenotypes for gene: DHPS were set to Abnormal muscle tone; Global developmental delay; Intellectual disability; Seizures; EEG abnormality; Behavioral abnormality; Abnormality of head or neck
Penetrance for gene: DHPS were set to Complete
Review for gene: DHPS was set to GREEN
Added comment: Ganapathi et al. (doi.org/10.1016/j.ajhg.2018.12.017 - PMID : NA) report on 5 individuals from 4 unrelated families with biallelic pathogenic variants in DHPS.

The phenotype consisted of DD/ID (5/5), tone abnormalities (hypotonia/hypertonia/spasticity - 5/5), seizures (5/5 - in one case though unclear staring spells) with EEG abnormalities (5/5). Additionally most individuals displayed behavioral issues, or some common facial features.

Several other disorders had been ruled prior to the diagnosis, in all cases by exome sequencing.

All individuals harbored a specific missense variant (c.518A>G or p.Asn173Ser) in trans with various other variants incl. a splice site mutation (c.1014+1G>A), an in-frame deletion of 2 amino acids (c.912_917delTTACAT or p.Tyr305_Ile306del) or a variant abolishing the translation initiation codon (c.1A>G or p.Met1?) [All variants using NM_001930.3 as a reference].

Deoxyhypusine synthase (encoded by DHPS) is an enzyme participating in the first step of hypusine synthesis, an amino-acid which is specific to eukaryotic initiation factor 5A (eIF5A) and its homolog (eIF5A2).

eIF5A, its hypusinated form and DHPS have all been previously implicated in cellular proliferation/differentiation. eIF5A has also been proposed to be a mRNA translation elongation factor. A role of eIF5A in neuronal growth and survival has been proposed previously (all ref. in present article).

Neither eIF5A, nor DHPS or DOHH (an enzyme required for the second step of hypusination) have been associated to any disorders previously. Mutations in genes encoding other eukaryotic elongator factors (eg. EEF1A2, EEF2) have been associated with neurodevelopmental disorders.

Concerning the DHPS variants reported:

cDNA studies suggested that the c.1014+1G>A variant is translated but results in aberrant splicing and truncation of the protein before its active site.

The in-frame deletion as well as the missense variant were shown to have absent or partial (20%) enzyme activity in vitro respectively compared to wild-type (following expression in E.coli BL21(DE3) cells).

In line with this, reduced hypusination of eIF5A was observed for these 2 variants when compared to wild-type DHPS, upon co-transfection of constructs overexpressing DHPS (wt or mut.) and eIF5A in HEK293T cells.

Absence of homozygous DHPS LoF variants in population databases might suggest that complete deficiency is incompatible with normal embryonic development. Mice heterozygous for Dhps deletion do not demonstrate severe phenotypes, though homozygosity is embryonically lethal (PMIDs: 21389784, 21850436).
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DHPS is not associated with any phenotype in G2P, nor in OMIM.
This gene is not - at least commonly - included in gene panels for ID offered by diagnostic laboratories.
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As a result, DHPS can be considered for inclusion in this panel as green (or amber).
Sources: Literature