| Domain | Evidence-backed finding/statistic | Suggested ontology terms | Evidence type/strength |
|---|---|---|---|
| Disease identity | DHX30-related neurodevelopmental disorder; established name **neurodevelopmental disorder with severe motor impairment and absent language (NEDMIAL)**; broader spectrum also described as neurodevelopmental disorder with variable motor and language impairment. **OMIM 617804**. (pqac-00000006) | OMIM:617804; NEDMIAL | Curated disease identity; strong |
| Causal gene | Pathogenic germline variants in **DHX30**, encoding an ATP-dependent DExH-box RNA helicase, cause the disorder. (pqac-00000002, pqac-00000006) | DHX30; RNA helicase activity (GO:0003724); ATP-dependent activity | Human genetic plus functional evidence; strong |
| Core severe phenotype | All **19/19 (100%)** individuals with heterozygous helicase-core-motif missense variants had global developmental delay/intellectual disability, severe speech impairment, and gait abnormalities. (pqac-00000002) | HP:0001263 Global developmental delay; HP:0001249 Intellectual disability; HP:0002167 Speech delay; HP:0001288 Gait disturbance | Multicenter human cohort; strong, but small sample |
| Language | **74%** of severe helicase-core-missense carriers were nonverbal; absent or minimal expressive language is a defining manifestation. (pqac-00000001) | HP:0001344 Absent speech | Human cohort; moderate–strong |
| Motor development | Only **47%** of severe helicase-core-missense carriers learned to walk; those who walk commonly have an abnormal or ataxic gait. (pqac-00000001) | HP:0001270 Motor delay; HP:0001288 Gait disturbance; HP:0001251 Ataxia | Human cohort; moderate–strong |
| Muscle tone | Hypotonia occurred in **95%** of severe helicase-core-missense carriers. (pqac-00000001) | HP:0001252 Hypotonia | Human cohort; strong for severe subtype |
| Feeding | Feeding difficulties occurred in **84%** of severe helicase-core-missense carriers. (pqac-00000001) | HP:0011968 Feeding difficulties | Human cohort; moderate–strong |
| Growth | Microcephaly occurred in **81%** of severe helicase-core-missense carriers; poor growth has also been reported in individual cases. (pqac-00000001, pqac-00000008) | HP:0000252 Microcephaly; HP:0001508 Failure to thrive | Cohort plus case evidence; moderate–strong |
| Musculoskeletal | Joint hypermobility occurred in **74%** of severe helicase-core-missense carriers; atraumatic dislocation, contractures, and foot deformities have been described. (pqac-00000001, pqac-00000012) | HP:0001382 Joint hypermobility; HP:0001373 Joint dislocation | Cohort plus case evidence; moderate |
| Neurological/behavioral spectrum | Seizures, autistic features or stereotypies, sleep disturbance, strabismus/nystagmus, and impaired social communication occur variably and are not obligatory. In an earlier 14-person comparison, seizures occurred in 3/14. (pqac-00000007, pqac-00000014) | HP:0001250 Seizure; HP:0000729 Autistic behavior; HP:0002360 Sleep disturbance; HP:0000486 Strabismus; HP:0000639 Nystagmus | Small cohorts/case series; limited–moderate |
| Neuroimaging | MRI may be normal or show delayed/hypomyelination, reduced white matter, ventriculomegaly, cerebral/cerebellar atrophy, or corpus-callosum abnormalities; no single diagnostic imaging signature is established. (pqac-00000000, pqac-00000010) | HP:0002119 Ventriculomegaly; HP:0001272 Cerebellar atrophy; HP:0007360 Abnormality of the corpus callosum | Human case series; variable, moderate |
| Inheritance | Usually **autosomal dominant and de novo**. Recurrence in siblings from clinically unaffected parents demonstrates parental gonadal/germline mosaicism; an inherited truncating variant from a mosaic mother and a de novo mosaic affected individual have also been reported. (pqac-00000000, pqac-00000002, pqac-00000009) | Autosomal dominant inheritance; HP:0003745 Genetic anticipation not supported | Human segregation evidence; strong |
| Variant–mechanism distinction | Heterozygous missense variants in conserved helicase-core motifs cause the classic severe phenotype by reducing ATPase/RNA-helicase activity while promoting abnormal stress-granule formation and global translation impairment. Haploinsufficiency/truncating variants generally cause a milder phenotype. (pqac-00000002, pqac-00000005) | GO:0003724 RNA binding; GO:0006412 Translation; GO:0010494 Cytoplasmic stress granule | Human genotype–phenotype correlation plus cellular/biochemical assays; strong |
| Mitochondrial biology | DHX30 also has mitochondrial and cytoplasmic forms and associates with mitoribosomal transcripts/ribosomes; depletion alters mitoribosomal-protein translation and mitochondrial energy metabolism. Direct contribution of this pathway to NEDMIAL manifestations remains inferred because experiments used non-neural cancer-cell models. (pqac-00000017, pqac-00000019) | GO:0005739 Mitochondrion; GO:0005761 Mitochondrial ribosome; GO:0032543 Mitochondrial translation | In-vitro mechanistic evidence; indirect for NEDMIAL |
| Diagnosis | Molecular confirmation requires identifying a pathogenic or likely pathogenic **DHX30** variant, preferably by trio exome/genome sequencing or a neurodevelopmental-disorder panel, followed by segregation and parental mosaicism assessment. CMA may detect deletions involving DHX30 but is often nondiagnostic for sequence variants. (pqac-00000000, pqac-00000008, pqac-00000009) | Genetic testing; whole-exome sequencing; whole-genome sequencing; chromosomal microarray | Human diagnostic implementation; strong for sequencing utility |
| Zebrafish models | Expression of pathogenic helicase-core variants caused embryonic developmental defects, partly rescued by wild-type DHX30. CRISPR dhx30-deficient zebrafish had impaired stress-granule assembly, altered sleep–wake activity, and reduced social preference despite viability and grossly normal morphology. (pqac-00000002, pqac-00000005) | NCBI Taxon:7955; GO:0032502 Developmental process; GO:0010494 Cytoplasmic stress granule | In-vivo functional model; moderate–strong |
| Mouse model | Complete **Dhx30** knockout is reported to cause early embryonic lethality, limiting its ability to model the heterozygous human neurological phenotype. (pqac-00000006) | NCBI Taxon:10090; HP:0003826 Stillbirth/embryonic lethality concept | Model-organism database/review evidence; moderate |
| Treatment status | No approved disease-modifying, gene, RNA, or targeted therapy and no relevant interventional DHX30 trial were identified. Current care is individualized and symptomatic—developmental therapies, communication support, nutritional/feeding care, mobility/orthopedic management, and standard treatment of seizures or sleep problems. | Physical therapy; occupational therapy; speech and language therapy; augmentative communication; anticonvulsant therapy | Clinical practice extrapolation; no controlled disease-specific treatment evidence |
| Evidence gaps | Population prevalence/incidence, penetrance, unbiased natural history, adult survival, standardized quality-of-life outcomes, validated biomarkers, modifier genes, protective factors, gene–environment interactions, patient-derived neural models, and treatment-response rates are unknown. Published frequencies are vulnerable to small-sample and ascertainment bias. (pqac-00000002, pqac-00000006) | Natural history study; patient registry; quality of life | Major evidence gaps; certainty low |


*Table: Knowledge-base-ready summary of identifiers, severe-subtype phenotype frequencies, inheritance, molecular mechanisms, diagnosis, models, treatment status, and major evidence gaps. Frequencies primarily describe 19 individuals with helicase-core-motif missense variants and should not be generalized to all DHX30 variant classes.*