PUS7-Related Neurodevelopmental Disorder (IDDABS) — Comprehensive Research Report

Prepared: 2026-08-01 · Target: PUS7-Related Neurodevelopmental Disorder · MONDO:0032687 · Category: Mendelian (autosomal recessive)

Scope and evidence note. This report is assembled from primary literature (PubMed/PMC), OMIM, HPO, ClinVar, HGNC, UniProt, GTEx, Human Protein Atlas, G2P, Alliance of Genome Resources, MGI/IMPC, and ClinicalTrials.gov. Eight primary references were verified against fetched abstracts/full text already cached in references_cache/ (PMID:30526862, 30778726, 31583274, 33100873, 35144859, 37067188, 42226002, 42249560). Ontology term IDs below are suggestions and must be confirmed with just validate-terms / OAK before committing to a KB entry. Sections where no data exist are stated explicitly rather than inferred.

1. Disease Information

Overview

PUS7-related neurodevelopmental disorder is an ultra-rare autosomal recessive syndrome caused by biallelic loss-of-function variants in PUS7, which encodes the RNA-independent pseudouridine synthase 7. The core phenotype is moderate-to-severe intellectual disability with delayed or absent speech, progressive (postnatal-onset) microcephaly, short stature/growth retardation, and prominent early-onset behavioral disturbance — most characteristically aggression, with self-injurious behavior in a subset. It belongs to the growing family of tRNA-modification disorders (alongside PUS1, PUS3, ADAT3, WDR4, NSUN2, TRMT10A), in which perturbed translational fidelity disproportionately injures the developing CNS.

The disorder was defined in 2018 by two independent groups. Muda et al. (2026) summarize the current state: "Pathogenic variants in PUS7, encoding pseudouridine synthase 7, cause a rare neurodevelopmental disorder marked by intellectual disability, microcephaly, short stature, and behavioral disturbances." (PMID:42226002)

Key identifiers

Synonyms / alternative names

• Intellectual developmental disorder with abnormal behavior, microcephaly, and short stature (IDDABS) — OMIM-preferred
• PUS7 deficiency
• PUS7-related neurodevelopmental disorder(s)
• PUS7-related syndrome / PUS7-related intellectual disability
• PUS7-related intellectual disability with speech delay, microcephaly, short stature and aggressive behavior (G2P label)
• Intellectual disability with growth retardation, PUS7-related

Provenance of the information

Essentially all knowledge derives from aggregated disease-level resources built from individual case reports and small multiplex-family cohorts — not from EHR-derived or registry-scale populations. The evidence base is:

Total published: ~30 individuals worldwide. There is no patient registry, no natural-history study, and no HPO-annotated cohort beyond n=9 (the current HPO frequency data for OMIM:618342 derive from the 2018–2019 reports).

2. Etiology

Primary causal factor

Biallelic (homozygous or compound heterozygous) loss-of-function variants in PUS7 (7q22.3). This is a monogenic, fully genetic etiology with no known environmental, infectious, or multifactorial contribution. Causality is established by:

1. Segregation in multiple independent multiplex families with autozygosity mapping and a combined LOD score of 3.4 for chr7:96,488,196–109,035,887 (hg19) across two families (PMID:30778726).
2. Direct biochemical demonstration of the molecular defect. de Brouwer et al.: "We show that the disease-related variants lead to abolishment of PUS7 activity on both tRNA and mRNA substrates." (PMID:30526862). Shaheen et al.: "Functional characterization of the two mutations confirmed that both result in decreased levels of Ψ13 in tRNAs." (PMID:30778726)
3. Model-organism recapitulation of the behavioral phenotype. "pus7 knockout in Drosophila melanogaster results in a number of behavioral defects, including increased activity, disorientation, and aggressiveness supporting that neurological defects are caused by PUS7 variants." (PMID:30526862)
4. Cross-species complementation failure, establishing the missense allele as null: "expression of the yeast pus7-D478Y variant failed to detectably rescue the growth defect of the pus7Δ trm8Δ strain… This result indicates that the yeast Pus7-D478Y variant is a complete loss of function mutation." (PMID:30778726)
5. G2P confidence: Strong; biallelic; loss-of-function mechanism.

Risk factors

Genetic (causal): biallelic PUS7 LoF is necessary and sufficient. No susceptibility loci, polygenic risk, or GWAS signals for the Mendelian phenotype. (Note: the GWAS Catalog contains several variants at 7q22.3 for which PUS7 is merely the nearest gene — rs2392747, rs13310815, rs13307225, rs62484733, rs142226001. These are positional annotations, not established PUS7 trait associations, and should not be curated as susceptibility evidence.)

Consanguinity is the dominant epidemiological risk factor. Nearly all reported families are consanguineous (first-cousin unions in Pakistani, Syrian, Moroccan, Saudi, Egyptian, and Afghan pedigrees). Shaheen et al. mapped disease via "regions of homozygosity >2Mb as surrogates of autozygosity given the parental consanguinity." The two US siblings (PMID:35144859) are the notable exception — nonconsanguineous, compound heterozygous — showing that the disorder is not restricted to inbred populations.

Environmental risk factors: none identified. No toxin, exposure, maternal, perinatal, occupational, dietary, or lifestyle risk factor has been reported or plausibly implicated. Pregnancies and deliveries were repeatedly described as uneventful (e.g., PMID:30778726: "Her pregnancy, delivery and neonatal history was unremarkable").

Sex: No sex bias. Both sexes affected in roughly equal numbers across cohorts (autosomal recessive).

Protective factors

• Genetic: None known. Heterozygous carriers (parents, unaffected sibs) are consistently unaffected across all published pedigrees — establishing that a single functional PUS7 allele is fully sufficient, i.e., the gene is not haploinsufficient. This is the only "protective" genetic statement supportable.
• Hypomorphic-allele effect (genotype-dependent attenuation, not "protection"): Darvish et al. argue that a missense allele spares the growth phenotype — "The absence of highly extreme phenotypes such as short stature or microcephaly in this family might reflect genotype–phenotype correlation, since this family presented with a PUS7 missense mutation that may be hypomorphic, while previously reported families carried nonsense or frameshift mutations that may cause loss of function." (PMID:31583274). Note this is contradicted by Shaheen et al., whose p.Asp503Tyr missense patients had severe microcephaly and whose yeast complementation showed complete LoF — so the correlation is not robust.
• Environmental: No dietary, nutritional, or lifestyle protective factor identified. Avoiding consanguineous union reduces population risk but is a public-health/genetic-counseling consideration, not a biological protective factor.

Gene–environment interactions

None documented for the human disorder. However, two mechanistically relevant GxE-adjacent findings deserve curation as emerging/hypothesis-level mechanism, not as disease risk:

• Stress-inducible cytoplasmic relocalization of PUS7. "one of the principal mRNA pseudouridylating enzymes, pseudouridine synthase 7 (PUS7), exhibits a stress-induced accumulation in the cytoplasm of yeast and human epithelial lung cells… engineered PUS7 cytoplasmic localization increases cellular fitness under reactive oxygen species (ROS) and divalent metal ion stress." (PMID:41997936, Nat Commun 2026). Notably, "the modification status of tRNA sites targeted by PUS7 (Ψ13 and Ψ35) is unperturbed" under this stress relocalization.
• Heat-shock-inducible mRNA pseudouridylation by Pus7 in yeast (Schwartz et al., PMID:25219674), i.e., PUS7 activity is condition-dependent.

Whether cellular stress modulates phenotypic severity in PUS7-deficient patients is entirely untested — a good candidate KNOWLEDGE_GAP discussion.

3. Phenotypes

3a. Complete HPO annotation set (OMIM:618342, HPO/ontology.jax.org, n=9 evidence base)

3b. Phenotypes reported in the literature but NOT yet in the HPO annotation set

These should be curated with their own evidence and are the substance of the 2022–2026 phenotypic expansion:

3c. Notable NEGATIVE findings (important for differential diagnosis)

• Epilepsy is characteristically ABSENT. de Brouwer: seizures marked absent (−) in all six patients. Shaheen: "her behavior is described as aggressive… She has good general health otherwise and has no history of admissions or epilepsy"; "No epilepsy was reported. EEG recording was normal"; "He never developed epilepsy." Shaheen explicitly frames this: "the phenotype we present in the three study patients supports the consistent involvement of cognition and postnatal brain growth and lack of epilepsy in PUS7 deficiency." The one reported seizure case (PMID:33100873) carried a second pathogenic splice variant in AASS (hyperlysinemia type I, in which seizures are a recognized feature) — that patient is a confounded observation and should be curated with an explicit caveat.
• Brain MRI is usually normal. "Brain MRI showed normal brain architecture" (×2 timepoints, PMID:30778726); normal in 5/6 of de Brouwer's patients. Structural malformation is not part of this disorder despite the severe microcephaly.
• No mitochondrial disease. Unlike PUS1 (MLASA1), PUS7 "does not modify mitochondrial tRNAs" (PMID:30526862) — no lactic acidosis, myopathy, or sideroblastic anemia.
• Normal puberty and secondary sexual characteristics despite growth failure (PMID:30778726).
• Normal muscle tone and reflexes on neurological examination in several patients, despite hypotonia in others.
• Bone age matched chronological age (PMID:30778726) — the short stature is not a bone-maturation disorder.

3d. Phenotype characteristics

3e. Quality-of-life impact

No formal QoL instrument (EQ-5D, SF-36, PROMIS, PedsQL, or disease-specific measure) has been applied to this disorder. No published QoL data exist. Functional impact must be inferred from clinical narrative and should be curated as descriptive text, not as QoL scores:

4. Genetic / Molecular Information

Causal gene

PUS7 — pseudouridine synthase 7 (RNA-independent pseudouridylate synthase 7) - HGNC: hgnc:26033 · OMIM gene: 616261 · Entrez: 54517 · Ensembl: ENSG00000091127 - Locus: 7q22.3 (GRCh37 chr7:~104.9 Mb) - Previous symbol/alias: FLJ20485; "pseudouridylate synthase 7 homolog (S. cerevisiae)" - Transcript for HGVS: NM_019042.3 (older reports) / NM_019042.5 (current ClinVar) - Protein: UniProt Q96PZ0, "Pseudouridylate synthase 7 homolog", 661 aa - Domains: N-terminal R3H domain (predicted ssDNA/RNA binding) + TRUD catalytic domain, residues 370–580 (UniProt) - Active site: Asp-294 (catalytic nucleophile, UniProt). Note the apparent inconsistency: Shaheen et al. place p.Asp503 "within the TRUD domain (370–580)" — Asp503 is a conserved salt-bridge residue in the E. coli TruD homolog (Kaya et al. 2004), distinct from the Asp294 nucleophile. Both are catalytically required; do not conflate them. - Paralog: PUS7L (pseudouridine synthase 7-like), a separate gene also implicated in severe GDD/epilepsy (noted as "manuscript under review" in PMID:30778726) - Chromosomal abnormalities: PUS7 is contained within larger 7q22 deletions and ring chromosome 7 in ClinVar (e.g., 7q22.3-31.1 chr7:104536649-109624996 x1; several NC_000007.13:g.(?_104456677)_(...)del records). These are large CNVs with broader phenotypes and are not IDDABS per se; no isolated PUS7 single-gene deletion causing dominant disease has been reported (consistent with the recessive mechanism).

Constraint / population genetics

• gnomAD constraint metrics (pLI, LOEUF, o/e) could not be retrieved — the gnomAD browser and GraphQL endpoint are JS-rendered and were not fetchable, and GeneCards returned HTTP 403. Do not cite numeric constraint values without direct verification. What can be asserted: heterozygous carriers are consistently unaffected across every published pedigree, so PUS7 is not haploinsufficient, which predicts a permissive (high) LOEUF and low pLI.
• Causal variants are absent from population databases. Repeatedly documented: "none of them were present in public databases, including the Iranome browser, the Greater Middle-East variome, and the Genome Aggregation database (gnomAD), and disease databases such as ClinVar and the Human Gene Mutation Database" (PMID:31583274); "These variant are absent in gnomAD and dbSNP database" (PMID:33100873).
• Carrier frequency: Not established. No population carrier-screening data; no founder allele identified. All variants to date are private/family-specific — including the one recurrent variant, c.329_332delCTGA (p.Thr110Argfs*4), which appears independently in a Saudi family (PMID:30778726) and an Italian patient (PMID:37067188) — recurrence more likely reflects a mutational hotspot than a founder effect.

Reported pathogenic variants

From the primary literature (verified):

From ClinVar (PUS7[gene], retrieved 2026-08-01): 225 total records; 44 with pathogenic clinical significance. Representative pathogenic small variants annotated to Intellectual developmental disorder with abnormal behavior, microcephaly, and short stature:

c.1275G>A (p.Trp425Ter) · c.998del (p.Asn333fs) · c.1918C>T (p.Arg640Ter) · c.156_159del (p.Ile54fs) · c.1270G>T (p.Glu424Ter) · c.424del · c.1507del (p.Asp503fs) · c.920+4_920+7del (splice donor) · c.155_161delinsAAC (p.Leu52fs) · c.1399-1G>C (splice acceptor, Pathogenic/Likely pathogenic) · c.532C>T (p.Arg178Ter) · c.393_397del (p.Glu132fs) · c.1097_1098del (p.Leu366fs) · c.(1757+1_1758-1)_(1848+1_1849-1)del (multi-exon deletion)

Variant spectrum summary: The mutational spectrum is dominated by truncating alleles (frameshift, nonsense, splice-disrupting, single/multi-exon deletions), with a minority of missense variants clustered in or adjacent to the TRUD catalytic domain (p.Gly128Arg, p.Thr387Met, p.Asp503Tyr). All are germline; no somatic PUS7 driver mutations are established in cancer (PUS7's oncologic role is via overexpression, not mutation — see §6).

Functional consequence: Uniformly loss of function (G2P: "loss of function"). No gain-of-function or dominant-negative allele has been described. Importantly, the missense alleles behave as complete LoF in orthogonal assays, not partial — arguing against a simple truncating-vs-missense severity gradient.

ACMG/AMP classification support: Truncating alleles typically reach Pathogenic via PVS1 + PM2 + PP1 (segregation) ± PS3 (functional). Shaheen et al. explicitly propose the biochemical assay as an ACMG PS3 tool: "this may also serve as a very helpful assay for the proper classification of variants of unknown significance that will inevitably be encountered in this gene."

Modifier genes

None identified. Phenotypic variability (presence/absence of short stature, hearing loss, autistic features, self-injury) is unexplained and is a stated open question: "it also suggests that other aspects are more variable… it remains to be seen how common this, and indeed other, clinical features are in PUS7-related syndrome" (PMID:30778726). Bergès et al. (PMID:42249560) explicitly frame their 13-patient cohort as "allowing for improved genotype-phenotype correlations."

Caution — dual diagnosis, not modification: the AASS splice variant co-segregating in the Saudi family (PMID:33100873) is a second independent Mendelian diagnosis (hyperlysinemia type I), a classic consanguinity artifact. Do not curate it as a PUS7 modifier.

Epigenetic information

• Classical epigenetics (DNA methylation, histone marks): no data. No methylation episignature has been developed for PUS7 deficiency (in contrast to many Mendelian NDDs). No ENCODE/Roadmap/DiseaseMeth findings specific to this disorder. This is a notable, tractable gap — an EpiSign-style episignature would be a high-value diagnostic addition.
• Epitranscriptomics is the disease mechanism itself. PUS7 is an RNA-modification "writer." Pseudouridine (Ψ) is "the most abundant and widespread type of RNA epigenetic modification in living organisms" (PMID:29628141) and "the most abundant post-transcriptional modification in RNA, which is primarily thought to stabilize secondary structures of RNA" (PMID:30526862). This disorder is therefore best classified as an epitranscriptomic disorder — the pathological "epigenetic change" is loss of Ψ marks on tRNA, tRFs, mRNA, and snRNA. See §6.

5. Environmental Information

• Environmental factors: None. No toxin, radiation, pollutant, occupational, or teratogenic exposure is implicated. CTD/TOXNET searches return no PUS7-disorder environmental associations. (CTD does contain cadmium–circPUS7 chemical-transformation data — PMID:34232319, a cancer/in-vitro finding entirely unrelated to the NDD.)
• Lifestyle factors: Not applicable. No dietary, smoking, alcohol, or activity factor influences onset or course. Note the absence of a dietary treatment distinguishes this from other tRNA/metabolic NDDs.
• Infectious agents: Not applicable — this is not an infectious or infection-triggered disorder. (Two tangential findings must not be conflated with etiology: PUS7-mediated Ψ in SARS-CoV-2 RNA–host interactions, PMID:38028201; and Ψ prevalence in KSHV, PMID:40961145. These concern PUS7's role in viral RNA biology, not IDDABS causation.)
• Perinatal/obstetric factors: consistently unremarkable. One report of transient neonatal respiratory difficulty requiring oxygen and physiological jaundice — coincidental.

6. Mechanism / Pathophysiology

6.1 Normal PUS7 biology

PUS7 is a stand-alone, RNA-independent (snoRNA-independent) pseudouridine synthase of the TruD family — one of 13 human PUS enzymes, and one of only two (PUS7, TRUB1) that are principal mRNA Ψ writers. It isomerizes uridine to 5-ribosyluracil (pseudouridine, Ψ; CHEBI:17802 verify), which "permits additional hydrogen bonding" and increases base stacking, historically framed as an RNA-stabilizing mark.

Substrate repertoire (each substrate class defines a distinct downstream mechanism):

Substrate recognition requires more than the linear motif. Human PUS7 has "two additional subdomains" absent in the bacterial homolog that "contribute to tRNA recognition through increased interactions along the tRNA substrate," and "all structural elements of tRNA are required for productive interaction with PUS7 as the consensus sequence of target RNA alone is not sufficient" (PMID:34718722). Yeast Pus7 is "a promiscuous enzyme" / "an opportunistic enzyme that binds and modifies substrates with diverse sequences and structures", with "factors beyond inherent enzyme properties—such as enzyme localization, RNA structure, and competition with other RNA-binding proteins" setting substrate choice (PMID:35058356). Most recently, "USUAG, target uridine accessibility, and RNA architecture govern mRNA alteration by PUS7" and "PUS7 function varies among cell types separate from expression amounts" (PMID:42532042) — a cell-type-specific determinant that may explain neural selectivity.

Localization: nucleus (UniProt; HPA: "Mainly nuclear expression in all tissues", nucleoplasm), with stress-inducible cytoplasmic relocalization that expands mRNA (but not tRNA) targets (PMID:41997936).

Expression: Broad/housekeeping — HPA "Low tissue specificity" (Tau 0.28), "Non-specific — Basic cellular processes." GTEx median TPM: highest in EBV-transformed lymphocytes (21.1), fibroblasts (18.2), adipose (12.1), thyroid (11.9). Within brain there is a striking regional gradient: cerebellar hemisphere 11.2 and cerebellum 10.0 TPM vs. 2.0–4.8 TPM in cortex, hippocampus, amygdala, and basal ganglia — i.e., cerebellar expression is 3–5× cortical. de Brouwer et al. leverage exactly this: "The relatively high PUS7 expression levels in cerebellum and tibial nerve support a more specific role for PUS7 in neurodevelopment."

6.2 The causal chain (upstream → downstream)

[MOLECULAR / genetic]
Biallelic PUS7 loss-of-function variant (frameshift/nonsense/splice → NMD;
exon-15 deletion → NMD-escaping TruD-truncated protein; missense → catalytically dead)
│
▼
[MOLECULAR] Loss of PUS7 pseudouridine synthase activity
  "the disease-related variants lead to abolishment of PUS7 activity on both
   tRNA and mRNA substrates" (PMID:30526862)
│
├──────────────┬────────────────┬─────────────────┐
▼              ▼                ▼                 ▼
[MOLECULAR]      [MOLECULAR]      [MOLECULAR]       [MOLECULAR]
Loss of tRNA     Loss of Ψ8 on    Loss of mRNA Ψ    Loss of snRNA Ψ
Ψ13 (≥10-17      mTOG/5'TOG       at UGΨAG motifs   (U2 Ψ35; 7SK Ψ)
tRNAs) ± Ψ35,    tRFs             (dozens-hundreds  → splicing fidelity /
Ψ50                               of mRNAs)          Pol II elongation
│              │                │                 │
▼              ▼                ▼                 ▼
Reduced tRNA     Failure of tRF-  Altered mRNA      Aberrant pre-mRNA
stability &      mediated         stability &        splicing; altered
decoding         PABPC1 blockade  translation        transcription
fidelity              │                │                 │
└──────────────┴────────────────┴─────────────────┘
              │
              ▼
[CELLULAR — convergent hub] DYSREGULATED / GLOBALLY UPREGULATED PROTEIN SYNTHESIS
  "PUS7 inactivation in embryonic stem cells impairs tRF-mediated translation
   regulation, leading to increased protein biosynthesis" (PMID:29628141)
  Patient fibroblasts: elevated puromycin incorporation (SUnSET, p=2.1e-3),
  elevated MYC protein with normal MYC mRNA (p=4.9e-4) (PMID:35144859)
              │
┌─────────────────────┼──────────────────────┐
▼                     ▼                      ▼
[CELLULAR]             [CELLULAR]              [CELLULAR]
Impaired neural        Impaired stem-cell      Mildly decreased HPRT1
progenitor             commitment / germ-      protein (normal mRNA)
proliferation &        layer specification     (p=3.5e-3) → purine
differentiation        "defective germ layer   salvage insufficiency
(inferred)             specification"
│                     │                      │
▼                     ▼                      ▼
[TISSUE]               [TISSUE]                [ORGANISM]
Reduced brain          Reduced somatic         Hyperuricemia
growth; cerebellum     growth                  (8.7, 6.5 mg/dL)
disproportionately            │                      │
vulnerable (highest           │                      │
regional expression)          │                      │
│                     │                      │
▼                     ▼                      ▼
[ORGANISM] Progressive        [ORGANISM]         [ORGANISM] Lesch-Nyhan-like
postnatal microcephaly        Short stature,     self-injurious behavior +
│                     low weight         hyperuricemia (HPRT1-negative)
▼
[ORGANISM] Intellectual disability, absent/delayed speech,
aggression, autistic features, stereotypies, sleep disturbance,
sensorineural hearing loss

6.3 Mechanism detail by module

(a) tRNA hypomodification → translational infidelity (the canonical arm). Patient EBV-LCLs show "the pseudouridylation signal in EBV-LCLs of affected individuals was essentially abolished at the PUS7 substrates at position 13" and "All of these sites were at position 13 of various tRNAs" (PMID:30526862). CMCT primer-extension and HPLC in an independent cohort: "tRNAHis(GTG) and tRNAGlu(CTC) from LCLs of patients with the Asp503Tyr mutation lacked Ψ13", and purified tRNA-Val(AAC) "showed a reduction of 0.88 moles of Ψ relative to that from a WT control (1.75 moles/mole compared to 2.63 moles/mole)" while "the levels of the other analyzed tRNAVal(AAC) modifications (m5C, m2G) were very similar" — a clean, site-specific defect (PMID:30778726).

The disease-mechanism framing is explicit: "We and others have previously emphasized the predilection of Mendelian diseases caused by tRNA modification genes to CNS involvement and how this suggests the vulnerability of the brain to any perturbation of tRNA modification, presumably through its deleterious effect on protein synthesis" (PMID:30778726).

(b) tRF (mTOG)–PABPC1 axis → loss of translational braking (the best-resolved arm). PUS7 Ψ-modifies mini-tRFs containing a 5′ terminal oligoguanine (mTOG) at U8. Ψ-mTOG binds and inhibits PABPC1, and "this hinders the recruitment of translational co-activator PABPC1-interacting protein 1 (PAIP1) and strongly represses the translation of transcripts sharing pyrimidine-enriched sequences (PES) at the 5' untranslated region (UTR), including 5' terminal oligopyrimidine tracts (TOP) that encode protein machinery components" (PMID:35292784). Loss of PUS7 therefore releases the brake on 5′TOP/PES mRNA translation — i.e., derepresses translation of the translational machinery itself, a feed-forward amplification. "tRNA-derived fragments with five consecutive guanine residues are classified as 5′TOG, and these are significantly depleted in PUS7-knockout cells" (PMID:29628141).

(c) Codon-biased translation via tRNA Ψ50. In glioblastoma stem cells, "13 PUS7-dependent pseudouridine sites in 8 tRNA types" were mapped; "tRNA-Arg-CCG-2–1 at position 50 exhibited a dramatic decrease in pseudouridine modification upon PUS7 KO", and "PUS7-mediated pseudouridylation in tRNA inhibits codon-specific translation." Loss of PUS7 raises translation efficiency of the affected tRNA and de-represses CGG-codon-rich transcripts such as TYK2 at the protein but not mRNA level (PMID:35121864). This provides a codon-level mechanism for how a global "writer" loss produces selective proteome changes — the most plausible explanation for tissue-selective phenotypes.

(d) Purine-salvage secondary hit → Lesch-Nyhan phenocopy. The single most clinically actionable mechanistic finding: "the dysregulation of protein translation also resulted in mildly decreased levels of HPRT1 protein suggesting an association between dysregulated protein translation and the LNS-like phenotypic findings" (PMID:35144859). Patients had hyperuricemia (peaks 8.7 and 6.5 mg/dL vs normal 2.3–5.5) and self-injurious behavior without pathogenic HPRT1 variants, and were treated with allopurinol. This is a translationally-mediated partial HPRT1 deficiency — a genuine secondary metabolic mechanism, and mechanistically the disorder's link to purine metabolism (KEGG hsa00230 purine metabolism).

Critically, the paper distinguishes this from cancer: "Patient fibroblasts demonstrated upregulation of protein synthesis, including elevated MYC protein, but did not exhibit increased rates of cell proliferation" — high MYC/high translation without proliferation, i.e., neurodevelopmental rather than oncogenic output. The authors frame the paradox in the abstract: "Upregulated protein translation is a hallmark of cancer and is implicated in autism spectrum disorder, but the risks of developing each disease do not appear to be correlated with one another."

(e) Splicing and transcription arms (mechanistically established, disease-relevance untested). UniProt: PUS7 "regulates pre-mRNA splicing near alternative splice sites." U2 snRNA Ψ35 in the branch-site recognition region is required for efficient splicing (PMID:15611063, 21131909). And 7SK Ψ controls Pol II pausing: "PUS7 loss leads to hypo-pseudouridylation of 7SK, which promotes dissociation of the positive transcription elongation factor b (P-TEFb) complex from 7SK. The release of P-TEFb from 7SK increases serine 2 phosphorylation (Ser2P) in the RNA Pol II C-terminal domain and enhances transcription elongation" (PMID:41168165). Whether either arm contributes to IDDABS is unknown — curate as a mechanistic hypothesis (status: EMERGING) with a KNOWLEDGE_GAP.

(f) Direct neuronal/synaptic mechanism (the most disease-proximal recent evidence). Liu et al. 2025 provide the first in vivo mammalian link between PUS7 and synaptic plasticity: "we identified selective Ψ enrichment at exons of synaptic regulatory genes within ILPFC during fear extinction learning. Fear extinction in the ILPFC drives concomitant exonic Ψ deposition and upregulation of synaptogenic transcripts, processes that involve pseudouridine synthase PUS7. Crucially, PUS7 knockdown in the ILPFC selectively impaired fear extinction memory formation without altering baseline fear expression, establishing a causal link between Ψ-dependent RNA processing and activity-dependent synaptic structural remodeling in this microcircuit." (PMID:41094471). This supplies a plausible mechanism for the behavioral phenotype (aggression, autistic features, impaired learning) distinct from the growth phenotype — and is a strong candidate for a dedicated pathophysiology node.

(g) Neuronal cell-autonomy (Drosophila). "expression of pus7 only in neurons by using the elav-Gal4 driver was sufficient to alter fly behavior, suggesting that Pus7 exerts its activity through a neuronal function" (PMID:30526862). This is the key evidence that the mechanism is neuron-intrinsic, not secondary to systemic growth failure.

6.4 Molecular pathways, cell types, and processes

Pathways (KEGG/Reactome/GO): - RNA modification / pseudouridine synthesis (GO:0001522, GO:0031119 tRNA pseudouridine synthesis, GO:1990481 mRNA pseudouridine synthesis) - tRNA processing and maturation; tRNA pseudouridine(13) synthase activity (GO:0160150) - Translation initiation control (eIF4F/PABPC1–PAIP1 axis); negative regulation of translation (GO:0017148) - mTOR/5′TOP mRNA translational program (indirect, via PES/TOP derepression) - Pre-mRNA splicing (GO:0008380), mRNA processing (GO:0006397) - Pol II transcription elongation (P-TEFb/7SK) - Purine metabolism / purine salvage (KEGG hsa00230) — via HPRT1 protein reduction - Stem-cell commitment: regulation of hematopoietic stem cell differentiation (GO:1902036), regulation of mesoderm development (GO:2000380)

Additional suggested GO BP terms for pathophysiology nodes (verify with OAK): GO:0006412 translation; GO:0045727 positive regulation of translation; GO:0022008 neurogenesis; GO:0021895 cerebral cortex neuron differentiation; GO:0050803 regulation of synapse structure or activity; GO:0007612 learning; GO:0040007 growth; GO:0008285 negative regulation of cell population proliferation.

Molecular functions: GO:0009982 pseudouridine synthase activity; GO:0160150 tRNA pseudouridine(13) synthase activity; GO:0003723 RNA binding; GO:0019899 enzyme binding.

Cellular components: GO:0005634 nucleus (primary); GO:0005654 nucleoplasm (HPA); GO:0005737 cytoplasm (stress-induced, PMID:41997936); GO:0005829 cytosol (site of tRF/PABPC1 action).

Cell types (CL — suggestions, verify): | CL term | Cell type | Basis | |---|---|---| | CL:0000540 | neuron | Cell-autonomous requirement (elav-Gal4 rescue); ILPFC knockdown | | CL:0000047 | neuronal stem cell / CL:0000031 neuroblast | Inferred: progenitor-pool reduction underlying microcephaly (not directly demonstrated — knowledge gap) | | CL:0000121 | Purkinje cell | Speculative: cerebellum has 3–5× higher PUS7 expression than cortex (GTEx). No cerebellar pathology reported — flag as hypothesis. | | CL:0000037 | hematopoietic stem cell | Directly demonstrated: impaired engraftment of PUS7-depleted HSPCs (PMID:29628141, 35292784) — no clinical hematologic phenotype in patients, an important human–model mismatch | | CL:0002322 | embryonic stem cell | PUS7-KO ESC: increased protein synthesis, defective germ-layer specification | | CL:0000057 | fibroblast | Patient-derived assay system (SUnSET, MYC, HPRT1) | | CL:0000542 | lymphocyte (EBV-LCL) | Patient-derived assay system (CMCT, HPLC Ψ13) | | CL:0000855 | sensory hair cell / CL:0000202 auditory hair cell | Inferred for SNHL — not demonstrated |

6.5 Protein dysfunction

• Truncating alleles: transcript eliminated by NMD — "mRNA transcripts containing the premature stop codons were eliminated through surveillance mechanisms" (PMID:31583274). Effectively a null.
• Exon 15 deletion: "escaped the nonsense-mediated mRNA decay to encode a mutant protein missing the C terminus including the TruD catalytic domain" — a stable but catalytically dead protein, mechanistically distinct (potential for aberrant substrate sequestration; untested).
• Missense alleles: catalytic-domain destabilization. p.Asp503Tyr disrupts a residue "involved in a salt bridge in the E. coli TruD homolog"; p.Gly128Arg alters "an evolutionarily conserved glycine down to yeast."
• No misfolding/aggregation, no gain of function, no dominant-negative effect described.
• Structural resources: X-ray crystal structure of human PUS7 at 2.26 Å (PMID:34718722); S. cerevisiae Pus7 structure (PMID:35058356); T. thermophilus TruD (PMID:15135053); AlphaFold model available for Q96PZ0.

6.6 Metabolic, immune, and tissue-damage mechanisms

• Metabolic: the only established metabolic abnormality is hyperuricemia via translationally-reduced HPRT1 (purine salvage insufficiency; PMID:35144859) — plus hypoglycemia in the same siblings (mechanism unexplained). No amino-acid, organic-acid, lipid, or energy-metabolism defect. No lactic acidosis (contrast PUS1/MLASA1). No metabolomic/lipidomic study of patients exists.
• Immune system: no immune involvement in the human disorder. No immunodeficiency, autoimmunity, or inflammation reported. (Adjacent, non-clinical: PUS7 in macrophage phenotype regulation — VUB research portal; Trub1-mediated Ψ dispensable for immune development, PMID:41876669. Neither bears on IDDABS.)
• Tissue damage mechanisms: no oxidative stress, ischemia, fibrosis, necrosis, or degeneration. This is a developmental/hypoplastic disorder — failure of brain and somatic growth — not a destructive or neurodegenerative one. The single brain-atrophy report (1/6) is an outlier and MRI is normal in most patients.
• Biochemical abnormalities (patient-detectable): loss of tRNA Ψ13 (CMCT/HPLC); elevated global protein synthesis; elevated MYC protein; reduced HPRT1 protein; elevated serum uric acid.

6.7 Molecular profiling and advanced technologies

7. Anatomical Structures Affected

Organ level

Lateralization: All structural findings are bilateral and symmetric (microcephaly, hearing loss, dysmorphism, short stature). No lateralized or asymmetric involvement reported. Note the intriguing negative: laterality defects (a feature of motile-ciliopathy) are absent, and PUS7 has no cilia link.

Tissue and cell level

• Nervous tissue (UBERON:0003714) — neurons (CL:0000540) are the cell type with demonstrated cell-autonomous requirement (elav-Gal4 rescue; ILPFC knockdown).
• Peripheral nerve — GTEx tibial nerve is among the higher-expressing tissues; de Brouwer cites it as supporting neurodevelopmental specificity. No clinical peripheral neuropathy has been reported — an unexploited hypothesis worth flagging (nerve conduction studies have not been systematically performed).
• Connective/skeletal tissue — growth failure; cartilage/growth plate not studied.
• Cochlear sensory epithelium — inferred for SNHL; no histopathology.
• Assay tissues (not disease sites): dermal fibroblasts, EBV-LCLs, peripheral blood.

Subcellular level

Histopathology: No human neuropathology, biopsy, or autopsy data exist for this disorder. Report as a gap.

8. Temporal Development

Onset

• Congenital/prenatal: Head circumference is usually normal at birth — the microcephaly is characteristically acquired/postnatal and progressive. Shaheen et al.: "a phenotype comprising intellectual disability and progressive microcephaly." Exception: the two US siblings had OFC at the 1st and 13th centiles at birth with subsequent deceleration (PMID:35144859), and low birth weight (1500 g, −3 SD; 2500 g, −2 SD) occurs (PMID:30778726) — so prenatal growth restriction is present in a subset.
• Infantile onset (HP:0003593, 2/3) — developmental delay evident in year 1–2.
• Childhood onset (HP:0011463, 1/3) — milder cases may present at 3–5 years for developmental/speech evaluation.
• Onset pattern: insidious and chronic. No acute, subacute, or crisis presentation. Notably no metabolic decompensation — this disorder does not conform to metabolic_intoxication_decompensation.
• Presenting complaint: most often speech delay ± unexplained ID/microcephaly. Typical ages at first genetics evaluation in the literature: 2y7m, 4y7m, 6y.

Progression

Patterns

• Remission: None — neither spontaneous nor treatment-induced. No disease-modifying therapy exists.
• Critical periods: Mechanistically, the vulnerable window is early embryogenesis and early postnatal brain growth. Guzzi et al.: "a Ψ-driven posttranscriptional program steers translation control to impact stem cell commitment during early embryogenesis" (PMID:29628141) — implying the primary insult is prenatal/perinatal and largely irreversible by the time of diagnosis. Practical intervention windows are therefore symptomatic: early behavioral/speech intervention, early audiological surveillance (hearing loss is progressive and remediable with amplification), and early hyperuricemia detection (allopurinol prevents urate complications).
• Anticipation: Not applicable — not a repeat-expansion disorder.

9. Inheritance and Population

Epidemiology

• Prevalence: not established. Ultra-rare. No published prevalence or incidence estimate; no Orphanet epidemiology record (no ORPHA code). The only quantitative anchor is the cumulative case count: ~30 published patients worldwide as of mid-2026 (16 through 2025 per Muda et al.; +1 Muda 2026; +13 Bergès 2026).
• Recommended dismech Prevalence record: measure_type: CASES_IN_LITERATURE, prevalence_class: ULTRA_RARE, population: Worldwide, notes: "~30 patients reported in the literature 2018–2026 (16 through 2025, +1, +13)." Do not invent a rate_per_100000.
• Supporting quotes: "Since the first report in 2018, only 16 patients have been described" (PMID:42226002); "Since 2018, PUS7 deficiency has been described in 15 patients" (PMID:37067188); "papers reported that variants in PUS7 in 16 patients" (PMID:42249560).
• Incidence: unknown.
• Ascertainment caveat: The trajectory (6 → 16 → ~30 in 8 years, with 13 arriving in a single GeneMatcher cohort) indicates substantial under-ascertainment, not true ultra-rarity of the genotype. Muda et al. explicitly urge broader testing: "We recommend looking for PUS7 pathological variants when performing whole exome sequencing in children with this constellation of neurodevelopmental and behavioral signs."

Genetic etiology parameters

Population demographics

• Affected populations: Reported ancestries — Pakistani, Syrian, Moroccan, Saudi Arabian, Egyptian, Afghan, Italian, and the multinational Bergès cohort (contributing centers: France, Belgium, Netherlands, Germany, UK, USA, Pakistan, Saudi Arabia, Australia, Luxembourg). The heavy Middle Eastern/North African/South Asian representation reflects consanguinity-driven ascertainment, not population-specific genetic susceptibility.
• Geographic distribution: Global; no endemic region. The 2026 European/multinational cohorts confirm the disorder is not geographically restricted.
• Variant geography: No variant shows geographic clustering. p.Thr110Argfs*4 in Saudi and Italian patients argues against geographic partitioning.
• Sex ratio: Approximately 1:1, as expected for AR. de Brouwer: 1 female / 5 males across 3 families; Shaheen: 1 female / 2 males; Darvish: 1 male / 1 female; Naseer: 2 males; Han: 2 siblings. Pooled counts are male-leaning but small-sample and not statistically meaningful — do not assert a sex bias.
• Age distribution of reported patients: 2–18 years, per PMID:33100873 ("nine patients ranged in age from 2 to 18 years old"). No adults have been reported — the natural history beyond adolescence is completely unknown.

10. Diagnostics

Clinical tests

Laboratory tests | Test | LOINC (verify) | Purpose / finding | |---|---|---| | Serum uric acid | LOINC:3084-1 | Hyperuricemia (peaks 8.7, 6.5 mg/dL; ref 2.3–5.5). Recommended in all patients — treatable, and a mechanistic clue | | Plasma glucose | LOINC:2345-7 | Hypoglycemia reported | | Plasma amino acids / urine organic acids | — | Normal (rule out aminoacidopathy; note the AASS dual-diagnosis family had hyperlysinemia — an argument for keeping metabolic workup in the differential) | | Lactate | LOINC:2524-7 | Normal — distinguishes from PUS1/MLASA1 | | CBC | — | Normal (no cytopenia despite HSPC model data — human–model mismatch) | | tRNA Ψ13 quantification (research only) | — | CMCT primer extension and HPLC nucleoside analysis on patient LCLs; the definitive functional assay |

Biomarkers. There is no validated clinical biomarker. The mechanistically specific candidate is reduced tRNA Ψ13, which Shaheen et al. propose for variant interpretation: "this may also serve as a very helpful assay for the proper classification of variants of unknown significance." Additional research-grade candidates: elevated global protein synthesis (SUnSET/puromycin incorporation), elevated MYC protein, reduced HPRT1 protein, depleted 5′TOG/mTOG tRFs. None are FDA-listed or clinically available. Hyperuricemia is the only routinely measurable abnormality and is neither sensitive nor specific.

Imaging. Brain MRI — recommended, but expect a normal study. "Brain MRI showed normal brain architecture"; "both studies revealed normal brain architecture." Rare findings: generalized atrophy with ventricular enlargement (1/6), brain atrophy (PMID:33100873), incidental craniocervical stenosis (managed conservatively). MRI's role is exclusionary (rule out malformation, migration defect, leukodystrophy), not confirmatory. Serial OFC plotting on growth charts is more diagnostically informative than imaging.

Functional tests. Not applicable (no pulmonary/cardiac involvement).

Electrophysiology. - Audiology / ABR / audiometry: Essential and under-recognized. SNHL was initially misattributed to middle-ear effusion in one patient — "Hearing loss was suspected due to chronic middle ear effusion but her poor response to ventilation tubes prompted re-evaluation and sensorineural hearing loss was confirmed." Recommend baseline plus serial audiology given progression. - EEG: Normal where performed ("EEG recording was normal"). Useful to document the absence of epilepsy. - ECG / EMG / NCS: No indication established. (Given tibial-nerve PUS7 expression, NCS is an untested question rather than a recommendation.)

Biopsy / histopathology. No role. No characteristic histopathology exists; no biopsy findings published.

Genetic testing

Recommended approach: PUS7 is not clinically suspected on gestalt alone — the phenotype is "common but non-specific" — so diagnosis is sequencing-first.

GTR: PUS7 clinical testing is registered (NIH GTR gene page 54517). ClinGen has published no variant-curation expert-panel specifications for PUS7, so ACMG/AMP interpretation is lab-specific.

Omics-based diagnostics

• RNA sequencing: Useful for splice-variant validation — how the c.398+1G>T allele was characterized ("41 bp or 55 bp deletions into the PUS7 mRNA", ~50% mRNA reduction). Recommend RNA-seq/RT-PCR for any candidate splice variant.
• Proteomics / metabolomics / epigenomics / liquid biopsy: No clinical diagnostic role. No methylation episignature exists (a genuine, tractable diagnostic gap).

Clinical criteria and differential diagnosis

No formal diagnostic criteria (no DSM/ICD/society guideline). Diagnosis = biallelic pathogenic PUS7 variants + compatible phenotype. No GeneReviews chapter exists.

Clinical suspicion gestalt (from PMID:42226002): core features (moderate/severe ID + delayed/absent speech + very-early-onset aggression + progressive microcephaly + short stature + mild facial dysmorphism) plus one or more of the "peculiar" features (sensorineural hearing loss, autistic traits, self-injurious behavior, motor stereotypies).

Differential diagnosis:

Screening

• Newborn screening: not included, and not appropriate — no biochemical marker, no presymptomatic treatment. No ACMG RUSP inclusion.
• Carrier screening: Not on any expanded carrier screening panel. Gene-level sequencing is required (private alleles). Highest-value use: consanguineous couples with an affected relative.
• Cascade/family screening: Indicated. Test at-risk siblings and offer carrier testing to relatives once the familial variant is known.
• Prenatal / PGT: Available once the familial variant is known — the principal current clinical benefit of diagnosis. Shaheen et al.: "the benefit of discovering these disease-gene links… is currently limited to establishing an accurate molecular diagnosis and prevention through informed reproductive choices."
• Risk stratification: Unexplained ID + progressive microcephaly + very-early aggression, especially with consanguinity or an HPRT1-negative LNS-like presentation → prioritize WES with PUS7 in the analysis pipeline.

11. Outcome / Prognosis

Important caveat: All prognostic statements below are inferences from ~30 cross-sectional case reports of patients aged 2–18 years. No natural-history study, registry, or survival analysis exists, and no adult patient has been reported. Curate prognosis with low confidence and an explicit KNOWLEDGE_GAP.

Survival and mortality

• Survival rate (5-/10-year/overall): not reported. No deaths have been reported among published patients.
• Life expectancy: not established. No data. The absence of epilepsy, mitochondrial disease, progressive neurodegeneration, cardiac or respiratory involvement, and the observation of patients reaching 16–18 years in apparently stable general health ("She has good general health otherwise and has no history of admissions") are consistent with survival into adulthood, but this is inference, not evidence.
• Mortality rate / disease-specific mortality: not reported.

Morbidity and function

• Morbidity is high and lifelong, driven by cognitive, communication, and behavioral impairment rather than by organ failure.
• Disability outcomes: Lifelong dependency for most. Documented functional endpoints: special education placement (multiple patients), inability to read or write, expressive vocabulary limited to ~30 words at age 16, non-ambulation at age 9 in the most severe case, IQ 44–48 where measurable.
• Quality of life measures: None applied. No EQ-5D, SF-36, PROMIS, PedsQL, or disease-specific instrument has been used. This is a clear gap for a rare-disease natural-history study.

Disease course and complications

Prediction

• Prognostic factors: None validated. Candidate (weak, contested) factor: variant class — Darvish et al. suggest missense/hypomorphic alleles spare microcephaly and short stature, but Shaheen's p.Asp503Tyr missense patients had severe microcephaly and complete LoF in yeast, so the correlation does not hold. Bergès et al. (PMID:42249560) explicitly aim to improve genotype–phenotype correlation with 13 new patients and 15 new variants — this paper is the priority follow-up read for prognostic factors.
• Prognostic biomarkers: None. (Note: PUS7-related prognostic biomarkers do exist in oncology — high PUS7 predicts worse survival in glioblastoma, and mTOG dysregulation "is clinically associated with leukaemic transformation and reduced patient survival" in MDS. These are entirely separate disease contexts and must not be curated as prognostic markers for IDDABS.)

12. Treatment

There is no disease-modifying or curative therapy. Management is entirely symptomatic, supportive, and multidisciplinary. Shaheen et al. state the position plainly: "the benefit of discovering these disease-gene links… is currently limited to establishing an accurate molecular diagnosis and prevention through informed reproductive choices, it is likely that these revelations will inform the development of therapeutics in the future."

Pharmacotherapy

Advanced therapeutics

• Gene therapy / gene editing: None. No preclinical program. Conceptually challenging: the critical developmental window is prenatal, and correction would require broad CNS delivery.
• Cell therapy: None.
• RNA-based therapies: None for this disorder. But note a mechanistically striking opportunity: programmable/site-directed pseudouridylation (dCas13b-guided Ψ deposition was demonstrated for 7SK, PMID:41168165; reviewed in PMID:40394244, which covers "therapeutic applications including programmable pseudouridylation"). Substrate-specific Ψ restoration is a conceptual future direction, not a therapy. Similarly, PMID:42532042 shows "Perturbing structure through mutations or antisense oligos modulates pseudouridine levels" — an ASO-based lever on Ψ levels. Curate these as mechanistic_hypotheses / research directions, not as treatments.
• Targeted therapies: None. Critically, the existing PUS7-directed small molecules (C4, C17/NSC107512, IC50 92.15 nM in PBT003 GSCs) are PUS7 INHIBITORS developed for glioblastoma — they would be expected to worsen PUS7 deficiency and are contraindicated in concept. This is an important curation guardrail: do not import cancer PUS7 pharmacology as therapy for IDDABS.
• Immunotherapies: Not applicable.

Surgical and interventional

• No disease-specific surgery. Reported procedures were incidental: ventilation tubes for middle-ear effusion (ineffective — the loss was sensorineural); craniocervical stenosis "Neurosurgical consultation suggested that conservative management is sufficient."
• Hearing aids — documented: "he developed severe sensorineural hearing loss and hearing aid was used." (therapeutic_modality: DEVICE)
• Dental/orthodontic intervention for hypodontia, crowding, retained deciduous teeth.

Supportive and rehabilitative (the mainstay)

Experimental treatments and trials

ClinicalTrials.gov query for "PUS7" returns zero studies (API v2, 2026-08-01). No EU-CTR or WHO ICTRP entries identified. There are no clinical trials in this disorder.

Treatment outcomes, algorithms, strategy

• Response rates: Not reported for any intervention. Risperidone and allopurinol outcomes were not quantified in the source reports.
• Adverse events: No PUS7-specific safety data. Standard risperidone (weight gain, metabolic syndrome, EPS, hyperprolactinemia) and allopurinol (rash, rare SJS/TEN — note HLA-B*58:01 risk, relevant to the dismech drug_hypersensitivity_scar and Allopurinol_Induced_SJS_TEN entries) risks apply.
• Treatment algorithm: No published algorithm or guideline. Practical framework: (1) confirm molecular diagnosis; (2) baseline serum uric acid, glucose, audiology, OFC plotting, MRI (exclusionary); (3) early habilitation (speech/PT/OT/special ed); (4) structured behavioral management, escalating to antipsychotic for refractory aggression/self-injury; (5) allopurinol if hyperuricemic; (6) serial audiology and growth monitoring; (7) genetic counseling and cascade testing.
• Combination therapy / personalized medicine: No genotype-guided treatment exists.

13. Prevention

Prevention levels

• Primary prevention (preventing disease occurrence): The only effective lever is reproductive, not exposure-based, because the etiology is purely genetic.
• Genetic counseling for consanguineous couples and for families with an affected child (25% recurrence risk per pregnancy).
• Prenatal diagnosis (CVS/amniocentesis with targeted variant testing) and preimplantation genetic testing (PGT-M) once the familial variant is known.
• Community-level consanguinity counseling / premarital genetic counseling programs, which are established public-health interventions in several of the high-ascertainment populations. This is the highest-impact population measure.
• Shaheen et al. name this explicitly as the current benefit of diagnosis: "prevention through informed reproductive choices."
• Secondary prevention (early detection):
• Early WES in unexplained ID + microcephaly — Muda et al.'s explicit recommendation. Shortens the diagnostic odyssey and enables the interventions below.
• Cascade carrier testing in extended families.
• No population newborn or presymptomatic screening is appropriate (no biochemical marker, no presymptomatic therapy).
• Tertiary prevention (preventing complications in affected individuals) — the most actionable domain:
• Serum uric acid monitoring → allopurinol to prevent urate nephropathy, nephrolithiasis, and gout.
• Serial audiology to detect progressive SNHL early and fit amplification — prevents avoidable additional communication loss. Also prevents misdiagnosis as conductive/effusion-related loss.
• Structured behavioral management to reduce self-injury-related physical harm.
• Nutritional and swallowing assessment to prevent aspiration and worsening failure to thrive.
• Serial OFC and growth plotting to document progression and trigger review.
• Sleep hygiene management to reduce behavioral escalation.
• Dental surveillance.

Other prevention modalities

• Immunization: No disease-specific vaccine strategy. Routine childhood immunization per schedule; no contraindication.
• Behavioral interventions to reduce risk: Not applicable to disease occurrence (genetic etiology). Behavioral intervention is therapeutic, not preventive of the disorder.
• Public health interventions: Premarital/preconception genetic counseling and consanguinity-awareness programs in high-consanguinity populations; expansion of WES access in low-resource settings where much of the reported patient population resides.
• Environmental interventions: Not applicable — no environmental contribution.
• Prophylaxis: Allopurinol functions as prophylaxis against urate complications in hyperuricemic patients. No other prophylactic medication or procedure.
• Risk stratification for targeted prevention: consanguineous families with an affected proband; families with an unexplained ID + progressive microcephaly + early aggression phenotype.

14. Other Species / Natural Disease

Taxonomy and orthology (Alliance of Genome Resources, all "high" confidence, best-score across methods)

PUS7 is broadly conserved from yeast to human, which is central to the disease evidence base.

Naturally occurring disease in other species

• None. No naturally occurring PUS7-related disorder is recorded in OMIA for dogs, cats, cattle, horses, or any other species. No wildlife or companion-animal disease.
• Veterinary relevance: none. All animal data are experimentally induced.
• One tangential agricultural genomics hit: PUS7 appeared in a GWAS for body weight in Chinese native ducks (PMID:38909509) — a statistical association in a production trait, not a natural disease model, and should not be curated as such.

Comparative biology

• Evolutionary conservation of mechanism is strong and load-bearing for the disease argument:
• Yeast Pus7 catalyzes Ψ13 in cytoplasmic tRNAs and Ψ35 in pre-tRNA-Tyr(GUA) — the same positions as human PUS7.
• Yeast complementation established human residue Asp503 as functionally essential: "This result indicates that the yeast Pus7-D478Y variant is a complete loss of function mutation, and thus that the importance of the human Thr503 residue is conserved among eukaryotes." (PMID:30778726) (Note the paper's internal typo — "Thr503" for Asp503.)
• p.Gly128 is "an evolutionarily conserved glycine down to yeast."
• Substrate motif conserved: "in yeast and human PUS7 identify a core motif UGΨAG."
• Comparative pathology / species differences:
• Human PUS7 has two additional subdomains absent from the bacterial homolog, which "contribute to tRNA recognition through increased interactions along the tRNA substrate" (PMID:34718722) — recognition mechanism, and therefore substrate breadth, is not fully conserved; caution when extrapolating from prokaryotic/yeast structural work.
• Yeast/T. thermophilus TruD modifies U13 and U35 (PMID:40138658); the U50 activity was described in human GSCs (PMID:35121864).
• The behavioral phenotype (hyperactivity, disorientation, aggression) is recapitulated in Drosophila, but the growth/microcephaly phenotype has no described animal counterpart — a genuine cross-species gap.
• Transmission / zoonosis / cross-species susceptibility: Not applicable — non-infectious genetic disorder.

15. Model Organisms

15a. Drosophila melanogaster — the flagship behavioral model

Gene: Pus7 / FBgn0035901 (CG6745), Chr 3L. Alleles: Pus7^fs (frameshift) and Pus7^UAS.cBa; FlyBase annotates these as models of IDDABS.

Type: Whole-animal knockout + tissue-specific (neuronal) UAS/GAL4 rescue — the only in vivo model demonstrating a causal, cell-autonomous, neuronal basis for the behavioral phenotype.

Phenotype recapitulation (PMID:30526862):

Summary claim: "pus7 knockout in Drosophila melanogaster results in a number of behavioral defects, including increased activity, disorientation, and aggressiveness supporting that neurological defects are caused by PUS7 variants."

Limitations: No microcephaly/brain-size, growth, hearing, or speech correlate. Flies cannot model ID, language, or self-injury. Invertebrate translational machinery and tRNA repertoire differ. evidence_source: MODEL_ORGANISM.

15b. Saccharomyces cerevisiae — variant-interpretation model

Gene: PUS7 / SGD:S000005769. Design: pus7Δ in a trm8Δ background, which "grows very poorly at 33°C and higher temperatures, due to rapid tRNA decay of tRNAVal(AAC)" — a temperature-sensitive growth readout for Pus7 function. Humanized-residue allele pus7-D478Y (≡ human D503Y) expressed from a CEN/URA3 plasmid under the native promoter.

Result: "expression of the yeast pus7-D478Y variant failed to detectably rescue the growth defect of the pus7Δ trm8Δ strain." (PMID:30778726)

Application: The most directly clinically useful model — a scalable functional assay for classifying PUS7 missense VUS (ACMG PS3). Limitations: cannot model any organismal phenotype; humanized residues only; human PUS7 has eukaryote-specific subdomains yeast Pus7 lacks.

15c. Mus musculus — available but essentially uncharacterized for this disorder

Gene: Pus7 / MGI:1925947, Chr 5.

Allele resources (MGI, 24 total mutations/alleles): 9 gene-trapped, 9 endonuclease-mediated (CRISPR), 2 targeted, 2 chemically induced, 1 radiation-induced, 1 spontaneous. Available from IMPC/KOMP repositories.

Phenotype data: MGI records 3 phenotypes from 1 allele in a single genetic background. IMPC (MGI:1925947): 3 significant phenotypes; 18/24 physiological systems tested; significantly impacted systems: Mortality/aging, Homeostasis/metabolism, Embryo. (Specific MP terms and the viability call did not render in the fetched page — retrieve these directly from mousephenotype.org before curating any MP term.)

Critical assessment: No published mouse model of PUS7-related neurodevelopmental disorder exists. There is no report of a Pus7-null mouse with microcephaly, growth retardation, aggression, or cognitive impairment. This is the single largest gap in the field — a KNOWLEDGE_GAP and arguably a HUMAN_MODEL_MISMATCH candidate (IMPC's "Mortality/aging, Homeostasis/metabolism, Embryo" hits do not obviously map onto the human neurobehavioral phenotype, and the human-relevant systems may be untested or under-powered in the IMPC pipeline).

The closest mammalian in vivo neural evidence is a knockdown, not a germline model: "PUS7 knockdown in the ILPFC selectively impaired fear extinction memory formation without altering baseline fear expression" (PMID:41094471) — region-specific, adult-onset, AAV/shRNA-based. This demonstrates a mammalian PUS7 requirement for activity-dependent synaptic remodeling and learning, but does not model the developmental disorder.

15d. Cellular and in vitro models

15e. Model resources

MGI (informatics.jax.org, MGI:1925947) · IMPC (mousephenotype.org/data/genes/MGI:1925947) · IMSR / KOMP / EuMMCR for Pus7 alleles · FlyBase (FBgn0035901) · SGD (S000005769) · RGD (1307054) · ZFIN (ZDB-GENE-060620-1) · WormBase (WBGene00007101) · Xenbase · Alliance of Genome Resources (HGNC:26033) · Cellosaurus/ATCC for PUS7-KO HeLa · PRIDE PXD008676.

Appendix A — Verified abstract quotes for evidence items

These are exact quotes from fetched abstracts/full text, suitable for snippet: fields after just fetch-reference and just validate-references. Reference cache files already exist for PMIDs 29628141, 30526862, 30778726, 31583274, 33100873, 35144859, 37067188, 41094471, 41136621, 42226002, 42249560.

Appendix B — Ontology term suggestions summary

All IDs below require verification with just validate-terms / OAK before use. Only the GO terms in the "verified" column were confirmed against a UniProt annotation set in this session.

• MONDO: MONDO:0032687 ✅ (verified via OLS, with OMIM/GARD/MedGen/UMLS/DOID xrefs)
• HGNC: hgnc:26033 ✅ (verified via rest.genenames.org)
• GO (verified via UniProt Q96PZ0): GO:0009982, GO:0160150, GO:0003723, GO:0019899 (MF); GO:0001522, GO:0031119, GO:1990481, GO:0006397, GO:0008380, GO:0017148, GO:1902036, GO:2000380 (BP); GO:0005634 (CC)
• GO (additional, unverified suggestions): GO:0006412, GO:0045727, GO:0022008, GO:0021895, GO:0050803, GO:0007612, GO:0005829, GO:0005737, GO:0005654
• HPO: 50 terms enumerated in §3a (all sourced from ontology.jax.org for OMIM:618342) + 9 literature-expansion terms in §3b
• CL (unverified): CL:0000540, CL:0000047, CL:0000031, CL:0000121, CL:0000037, CL:0002322, CL:0000057, CL:0000542
• UBERON (unverified): UBERON:0000955, UBERON:0000956, UBERON:0002037, UBERON:0002743, UBERON:0001846, UBERON:0001844, UBERON:0001474, UBERON:0001684, UBERON:0001091, UBERON:0001134, UBERON:0002113, UBERON:0002107
• CHEBI (unverified): CHEBI:17802 (pseudouridine), CHEBI:8871 (risperidone), CHEBI:40279 (allopurinol), CHEBI:16704 (uric acid — verify)
• NCIT (unverified): NCIT:C15986, NCIT:C15302, NCIT:C159273, NCIT:C121351, NCIT:C181743, NCIT:C15240, NCIT:C15747, NCIT:C15433
• NCBITaxon: 9606, 10090, 10116, 7955, 7227, 6239, 559292, 8364

Appendix C — Explicit knowledge gaps (candidate discussions entries)

Appendix D — Curation guardrails (read before building the KB entry)

1. PUS7 cancer literature is a large trap. ~40 of ~86 PUS7 PubMed records concern oncology (glioblastoma, colorectal, gastric, pancreatic, HCC, ovarian, bladder, thyroid, osteosarcoma, TNBC, NSCLC, RCC). These describe PUS7 overexpression and its inhibition as therapy — the mechanistic opposite of this recessive LoF disorder. Do not import PUS7 inhibitors (C4, C17/NSC107512) as treatments; do not import PUS7-high prognostic biomarkers. If a viral_oncogenesis/hallmark module link is tempting, it belongs on a cancer entry, not here.
2. The Naseer 2020 family (PMID:33100873) is a dual diagnosis (PUS7 + AASS splice variant). The seizures, hypotonia, and possibly the brain atrophy in those patients may derive from hyperlysinemia type I, not PUS7. Curate any phenotype from this paper with an explicit caveat, and do not let it override the strong "epilepsy absent" signal from every other cohort.
3. The "PUS7 modifies Ψ50 in mitochondrial tRNA-Met" claim appearing in a 2025 secondary review conflicts with de Brouwer et al.'s primary statement that "PUS7… does not modify mitochondrial tRNAs" and with Cui et al.'s Ψ50 finding in cytosolic tRNA-Arg-CCG. Do not curate a mitochondrial tRNA target without primary-source verification.
4. Do not fabricate gnomAD constraint values. pLI/LOEUF/o-e could not be retrieved in this session (JS-rendered browser; GeneCards 403). Fetch directly before citing.
5. The Han 2022 (PMID:35144859) growth numbers extracted as "heights of 47.8 cm and 48 cm at ages 9–10" are almost certainly occipitofrontal circumference, not height. Re-read the primary table before curating any numeric growth value from that paper.
6. Bergès 2026 (PMID:42249560) and Muda 2026 (PMID:42226002) are paywalled, ahead-of-print, and not in EuropePMC/PMC (isOpenAccess: N, inEPMC: N). Only their abstracts are quotable today. The 15 new variants and the 17-case frequency table are not currently extractable — flag for a follow-up curation pass once full text is accessible.
7. evidence_source assignments: de Brouwer/Shaheen/Darvish/Naseer/Muda/Bergès clinical descriptions → HUMAN_CLINICAL. Patient LCL/fibroblast assays, ESC/GSC/HCT116 experiments, PUS7 crystal structures → IN_VITRO. Drosophila and mouse ILPFC knockdown → MODEL_ORGANISM. Yeast complementation → IN_VITRO (or MODEL_ORGANISM if treated as an organismal growth assay — pick one and be consistent). In silico pathogenicity predictions (SIFT/PolyPhen/CADD/MutationTaster) → COMPUTATIONAL; split these into separate evidence items from the clinical claims.
8. Frequency qualifiers: the HPO n/N values in §3a are legitimate derived-count evidence for frequency: bands, but they derive from n≤9 patients. Prefer citing the count explicitly in the evidence explanation over asserting a confident FrequencyEnum band, and follow docs/frequency-evidence-guidelines.md. Where a count is 1/3 or 1/6, consider omitting frequency: entirely.
9. NEC preflight passed. MONDO:0032687's identity anchors (OMIM:618342, causal gene PUS7, synonym IDDABS) are consistent across OMIM, UniProt, HGNC, G2P, ClinVar, and every primary paper. The gene named most frequently in the literature is the canonical gene. No named-entity confusion detected. Watch only for PUS7 vs PUS7L (a distinct paralog with a distinct, epilepsy-featuring phenotype) and PUS7 vs PUS1/PUS3.
10. Module conformance candidates (evaluate, don't assume): this disorder does not fit metabolic_intoxication_decompensation (no decompensation), lysosomal_substrate_accumulation, or any mitochondrial pattern. sensorineural_hair_cell_loss is a plausible partial conformer for the progressive SNHL node, and epilepsy_excitation_inhibition_imbalance should be explicitly not applied (epilepsy is characteristically absent). There is no existing dismech module for "translational-control / RNA-modification neurodevelopmental disorder" — the PUS1/PUS3/PUS7/ADAT3/WDR4/NSUN2/TRMT10A family would make a coherent new mechanism module and/or a Grouping (basis: SHARED_MECHANISM + SHARED_GENE_FAMILY), which is worth proposing.

Sources

Primary literature (PubMed/PMC): - de Brouwer et al. 2018, Am J Hum Genet — PMID:30526862 · full text PMC6288278 - Shaheen et al. 2019, Hum Genet — PMID:30778726 - Darvish et al. 2019, Neurol Genet — PMID:31583274 - Naseer et al. 2020, Saudi J Biol Sci — PMID:33100873 - Han et al. 2022, Mol Genet Metab — PMID:35144859 - Muda et al. 2023, Am J Med Genet A — PMID:37067188 - Muda et al. 2026, Am J Med Genet A — PMID:42226002 - Bergès et al. 2026, Clin Genet — PMID:42249560 - Guzzi et al. 2018, Cell — PMID:29628141 - Guzzi et al. 2022, Nat Cell Biol — PMID:35292784 - Cui et al. 2021, Nat Cancer — PMID:35121864 · Cancer Discov commentary · Trends Pharmacol Sci commentary - Purchal et al. 2022, PNAS — PMID:35058356 - PUS7 crystal structure, Nucleic Acids Res 2021 — PMID:34718722 - Liu et al. 2025, Mol Brain (ILPFC fear extinction) — PMID:41094471 - tRNA Ψ map / stand-alone PUS enzymes, Nat Cell Biol 2025 — PMID:41136621 - 7SK pseudouridylation & Pol II elongation, Nat Commun 2025 — PMID:41168165 - Cytoplasmic PUS7 & stress tolerance, Nat Commun 2026 — PMID:41997936 - Rodell et al. 2026, Cell Genomics (Nano-Mod-Amp) — PMID:42532042 - Luo et al. 2025, Nat Rev Mol Cell Biol — PMID:40394244 - Pseudouridine modification in the nervous system, Int J Neurosci — PMID:38407188 - Impact of pseudouridine on human tRNA, Biochem Soc Trans 2026 — PMID:42290177 - PUS7 as a context-specific cancer target, JPET 2026 — PMID:42190315 - Pseudouridine Synthase 7 in Cancer, Cells 2025 — PMID:40940790 - Full PUS7 PubMed result set (86 records)

Databases: - OMIM 618342 (IDDABS) · OMIM 616261 (PUS7) - HPO annotations, OMIM:618342 - MONDO:0032687 via EBI OLS4 - HGNC:26033 · UniProt Q96PZ0 - ClinVar PUS7 (225 records; 44 pathogenic) - EBI Gene2Phenotype PUS7 (G2P02633) · ClinGen PUS7 (no curation) - GTEx PUS7 expression · Human Protein Atlas PUS7 - Alliance of Genome Resources HGNC:26033 orthologs - MGI:1925947 (mouse Pus7) · IMPC Pus7 - FlyBase Pus7 FBgn0035901 · RGD Pus7 1307054 · ZFIN pus7 - NIH GTR PUS7 · ClinicalTrials.gov (0 studies for PUS7) - PRIDE PXD008676