| domain | best-supported finding | quantitative evidence | evidence type | key source/date |
|---|---|---|---|---|
| Identity / inheritance | CONDCA is a rare autosomal recessive neurodegenerative disease caused by biallelic AGTPBP1 (CCP1) variants; OMIM 618276 | Foundational cohort: 13 affected individuals from 10 unrelated families; later summaries cite ~18-20 reported patients | Human clinical-genetic cohort; disease database association | Shashi et al., *EMBO J* 2018, published 2018-11-12, DOI: https://doi.org/10.15252/embj.2018100540, PMID 30420557 (pqac-00000025, pqac-00000026); Open Targets EFO_0010256 (pqac-00000000) |
| Core phenotypes and frequencies | Early infantile/childhood-onset progressive neurologic disease with motor delay, hypotonia, weakness, cognitive impairment, cerebellar atrophy, and motor neuropathy/lower motor neuron involvement | Aggregated review of ~20 patients: motor delay 20/20; hypotonia 19/20; muscle weakness 16/18; cognitive delay 17/20; microcephaly 11/20; feeding difficulties 13/20; respiratory distress 9/20; cerebellar atrophy 18/20; corpus callosum dysplasia 6/20; muscle atrophy 9/18 | Human case-series synthesis from primary reports/review | Baltanás et al., *Biomedicines* 2021, DOI: https://doi.org/10.3390/biomedicines9091157 (pqac-00000003, pqac-00000001) |
| Natural history / onset | Onset is usually from birth to 20 months with progressive worsening; disease can be severe and fatal in childhood, though milder survivors exist | In the 2018 cohort, 6/13 had a fatal course; one summarized review reports 7/18 deaths; patient ages at presentation ranged from 7 months to 14 years in one review summary | Human cohort and review synthesis | Shashi et al. 2018 (pqac-00000025); Baltanás et al. 2021 (pqac-00000001, pqac-00000002) |
| MRI / neurodiagnostics | Brain MRI most consistently shows cerebellar atrophy; corpus callosum abnormalities and microcephaly are frequent co-findings | Cerebellar atrophy in 18/20 in aggregated review; severe or moderate cerebellar atrophy shown across many individuals in foundational cohort | Human imaging evidence | Shashi et al. 2018 (pqac-00000025, pqac-00000026); Baltanás et al. 2021 (pqac-00000003) |
| Electrophysiology / peripheral nerve | Disease affects cerebellum, spinal motor neurons, and peripheral nerves, typically with axonal motor neuropathy and denervation, while sensory involvement is less emphasized | Aggregated review: denervation 5/20, neurogenic changes 2/20, axonal motor neuropathy 5/20 | Human neurophysiology and pathology | Shashi et al. 2018 (pqac-00000025); Baltanás et al. 2021 (pqac-00000001, pqac-00000003) |
| Molecular mechanism | AGTPBP1/CCP1 loss causes defective tubulin deglutamylation, reduced D2-tubulin generation, and excess tubulin polyglutamylation, linking microtubule PTM dysregulation to neurodegeneration | Human muscle biopsy showed polyglutamylated tubulin accumulation; missense mutants lacked detectable catalytic activity for D2-tubulin generation in cell assays | Human molecular pathology; cell-based functional evidence | Shashi et al. 2018, DOI above (pqac-00000026, pqac-00000008) |
| Mechanistic downstream effects | Excess polyglutamylation impairs neuronal transport and is sufficient to drive neuron-autonomous degeneration; TTLL1 is a major pathogenic counter-enzyme in CCP1 deficiency | In mouse models, simultaneous TTLL1 loss fully rescued degeneration of selected neurons; transport defects affected multiple cargo classes in hippocampal neurons | Mouse genetics; cultured neuron experiments | Magiera et al., *EMBO J* 2018, DOI: https://doi.org/10.15252/embj.2018100440 (pqac-00000024); Bodakuntla et al., *EMBO J* 2021, published 2021-07-26, DOI: https://doi.org/10.15252/embj.2021108498 (pqac-00000023) |
| Diagnostics | Whole-exome sequencing is the key diagnostic approach because phenotype overlaps other pediatric neurodegenerative/cerebellar atrophy disorders; segregation testing is used for confirmation | 2024 Egyptian WES cohort: 7 patients from 6 families overall; 2 AGTPBP1 cases identified; sequencing described at ~50x average coverage | Human diagnostic study | Ashaat et al., *Molecular Neurobiology* 2024, published online 2023-12-28, DOI: https://doi.org/10.1007/s12035-023-03866-y (pqac-00000021, pqac-00000022) |
| Variant spectrum | Reported AGTPBP1 disease variants include nonsense, frameshift, splice, deletion, and missense alleles; truncating genotypes trend more severe than some missense genotypes | Foundational cohort identified 6 loss-of-function and 6 missense variants; variants were absent or extremely rare in population databases (AF below 0.00005 in cited summary) | Human clinical-genetic and functional evidence | Shashi et al. 2018 (pqac-00000026); Baltanás et al. 2021 (pqac-00000002) |
| Expanded phenotypes | Phenotypic spectrum may extend beyond classic cerebellar atrophy/motor neuron disease to atypical imaging or systemic findings | 2021 report described 2 siblings with homozygous c.3293G>A and neurodegeneration without cerebellar atrophy; 2023 case reported homozygous c.2447A>C (p.Gln816Pro) with seizures, dystonia, dilated cardiomyopathy, and caudate/putaminal/cerebellar atrophy | Human case reports | Türay et al., *Neurogenetics* 2021, DOI: https://doi.org/10.1007/s10048-021-00643-8 (pqac-00000004); Samur et al., *J Pediatr Neurol* 2023, DOI: https://doi.org/10.1055/s-0042-1749669 (pqac-00000018) |
| Recent 2024 human developments | New AGTPBP1 cases continue to expand mutational and phenotypic spectrum in consanguineous families | Ashaat 2024 reported 2 homozygous AGTPBP1 variants in Egyptian patients: novel c.2650A>C (p.Thr884Pro), likely pathogenic; and c.1534A>G (p.Thr512Ala), classified as VUS in that paper; cohort age range 1.5-18 years, all families consanguineous | Human WES cohort | Ashaat et al. 2024 (pqac-00000019, pqac-00000021, pqac-00000022) |
| Prognosis | Prognosis is generally poor with severe disability, progressive neurologic decline, and childhood mortality, but expressivity is variable | 6/13 fatal in Shashi 2018; milder survivors included a 14-year-old with spastic-ataxic movement disorder and mild intellectual disability in the foundational cohort | Human cohort | Shashi et al. 2018 (pqac-00000025, pqac-00000026) |
| Treatment status | No approved disease-modifying therapy or disease-specific clinical trial was identified; management is currently supportive and genetics-guided | Clinical trial search found no relevant registered interventional trial; supportive treatment reversed cardiomyopathy in one 2023 case report, but not the neurologic disease | Clinical trial landscape; case report | ClinicalTrials search result (pqac-00000000); Samur et al. 2023 (pqac-00000018) |
| Preclinical therapy signals (2025) | In the PCD mouse model, rhVEGF-B showed neuroprotective benefit, whereas rhIGF-1 did not under tested conditions | Abstract reports rhVEGF-B at moderate dosage "stopped the process of neuronal death" and restored motor, cognitive, and social functions; increased dosing was detrimental; rhIGF-1 showed no neuroprotective effect | Mouse preclinical therapeutic study | Pérez-Revuelta et al., *Int J Mol Sci* 2025, published 2025-01-10, DOI: https://doi.org/10.3390/ijms26020538 (pqac-00000014, pqac-00000015, pqac-00000016, pqac-00000017) |
| Model organism | The Purkinje cell degeneration (pcd) mouse is the best-established model and recapitulates cerebellar atrophy plus broader neurodegeneration; sheep are cited as having lower motor neuron-like disease with AGTPBP1 involvement | Mouse model shows Purkinje cell loss, cerebellar atrophy, peripheral nerve pathology, reduced motor neurons, excess polyglutamylation, and decreased D2-tubulin; review also cites ovine lower motor neuron disease | Mouse and comparative-animal evidence | Shashi et al. 2018 (pqac-00000027); Baltanás et al. 2021 (pqac-00000013, pqac-00000009) |


*Table: This table condenses the strongest available evidence for AGTPBP1-related childhood-onset neurodegeneration with cerebellar atrophy across clinical, molecular, diagnostic, prognostic, and model-system domains. It is useful as a quick-reference scaffold for a fuller disease knowledge-base entry.*