Kisho is an information platform, not a medical provider. Nothing on this site constitutes medical advice, diagnosis, or treatment recommendations. All content is aggregated from publicly available sources (including ClinicalTrials.gov, PubMed, FDA.gov, and Orphanet) and is provided for informational purposes only. Clinical trial eligibility, treatment decisions, and any health-related actions should always be discussed with a qualified healthcare professional. Kisho does not endorse any specific therapy, organization, or clinical trial. Terms of use · Privacy policy
Features include always present findings: Lower limb hyperreflexia; and very common findings: Spastic gait, Distal muscle weakness, and Hoffmann sign. 31 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Brain and nerves | 12 | Resting tremor, Gait ataxia, Spastic gait |
Bones and joints | 3 | Carpal bone hypoplasia, Delayed skeletal maturation, Abnormal pelvic girdle bone morphology |
Kidneys and urinary system | 2 | Urinary incontinence, Urinary urgency |
Digestive system | 2 | Gastroesophageal reflux, Vomiting |
Muscles | 2 | Distal muscle weakness, Corpus callosum atrophy |
Arms and legs | 2 | Lower limb spasticity, Lower limb hyperreflexia |
Eyes | 2 | Cataract, Nystagmus |
Growth and development | 1 | Short stature |
Neurocutaneous disorders due to mitochondrial proline synthesis defects comprise PYCR1-related autosomal recessive cutis laxa (ARCL), ALDH18A1-related ARCL, and ALDH18A1-related autosomal dominant cutis laxa (ADCL). These disorders are characterized by a generalized progeroid type of cutis laxa with recognizable dysmorphic features and, often, developmental delay . To date, 154 individuals have been reported: 114 with biallelic pathogenic variants in PYCR1 (PYCR1-related ARCL), 27 with biallelic pathogenic variants in ALDH18A1 (ALDH18A1-related ARCL), and 13 individuals with heterozygous de novo pathogenic variants in ALDH18A1 (ALDH18A1-related ADCL). The following description of the phenotypic features associated with this condition is based on these published reports . Table 2. Neurocutaneous Disorders due to Mitochondrial Proline Synthesis Defects: Frequency of Select Features
Feature | % of Persons w/Feature | Comment |
|---|---|---|
Cutaneous | Lax wrinkled skin | 100% |
ALDH18A1 encodes aldehyde dehydrogenase 18 family member A1 (795 aa). Bifunctional enzyme that converts glutamate to glutamate 5-semialdehyde, an intermediate in the biosynthesis of proline, ornithine and arginine Highest expression in Cells Cultured fibroblasts (95.6 TPM) and Cells EBV-transformed lymphocytes (93.1 TPM).
Hereditary spastic paraplegia 9A is associated with mutations in the ALDH18A1 gene on chromosome 10.
ALDH18A1 is classified as a druggable target (Druggable Genome, Enzyme, and Kinase categories) with score 0.0.
No consensus clinical diagnostic criteria for neurocutaneous disorders due to mitochondrial proline synthesis defects have been published.
Neurocutaneous disorders due to mitochondrial proline synthesis defects comprise PYCR1-related autosomal recessive cutis laxa (ARCL), ALDH18A1-related ARCL, and ALDH18A1-related autosomal dominant cutis laxa (ADCL). These disorders should be suspected in probands with the following clinical, laboratory, and imaging findings.
Clinical findings
Source: GeneReviews — "Neurocutaneous Disorders due to Mitochondrial Proline Synthesis Defects"
Table 4. Neurocutaneous Disorders due to Mitochondrial Proline Synthesis Defects: Differential Diagnosis
Gene(s) | Disorder | MOI | Key Features of Disorder |
|---|---|---|---|
ATP6V1E1 | V-ATP-ase-related cutis laxa (ARCL2A, 2C, 2D) (See ATP6V0A2-Related Cutis Laxa.) | AR | Generalized cutis laxa; Affected persons shorter than unaffected sibs; Variable intellectual disability; Seizures |
BANF1 | Nestor-Guillermo progeria syndrome, BANF1-related (OMIM 614008) |
Genetic testing for ALDH18A1 is available. Testing is considered confirmatory for diagnosis.
No approved treatments are currently available for hereditary spastic paraplegia 9A. The disease remains an area of unmet medical need.
Gene therapy approaches for hereditary spastic paraplegia 9A have been reported in the published literature.
No clinical practice guidelines for neurocutaneous disorders due to mitochondrial proline synthesis defects have been published. In the absence of published guidelines, the following recommendations are based on the authors' personal experience managing individuals with these disorders.
To establish the extent of disease and needs in an individual diagnosed with a neurocutaneous disorder due to a mitochondrial proline synthesis defect, the evaluations summarized (if not performed as part of the evaluation that led to the diagnosis) are recommended.
Table 5.
Neurocutaneous Disorders due to Mitochondrial Proline Synthesis Defects: Recommended Evaluations Following Initial Diagnosis
System/Concern | Evaluation | Comment
| Serum urine amino acids | To identify persons w/ levels of ornithine, citrulline, arginine, proline
| • Assess need for additional care for wound healing.
Assess risk for decubitus.
| Wound healing scarring tends to be normal, but lipodystrophy may risk of severe wounds.
| Brain MRI | To assess for gyral abnormalities, thin corpus callosum, ventricular dilatation, intracranial arterial tortuosity/ aneurysms
EEG | To assess for seizures
Full clinical neurologic exam | To assess tone, presence of movement disorders, spasticity
| Developmental assessment | • To incl motor, adaptive, cognitive, speech-language eval
Eval for early intervention/ special education
| Assess growth. | Consi...
Source: GeneReviews — "Neurocutaneous Disorders due to Mitochondrial Proline Synthesis Defects"
View trials for hereditary spastic paraplegia 9A
To monitor existing manifestations, the individual's response to supportive care, and the emergence of new manifestations, the evaluations summarized in are recommended. Table 7. Neurocutaneous Disorders due to Mitochondrial Proline Synthesis Defects: Recommended Surveillance
System/Concern | Evaluation | Frequency |
|---|---|---|
Neurologic | Clinical neurologic exam to assess for new seizures/ changes in seizures, movement disorders, spastic diplegia | Every 6 mos initially, then annually EEG |
Development | Monitor developmental progress educational needs. | Every 6 mos initially, then annually Growth |
Orthopedics | Assess for scoliosis, hip dislocation, joint hypermobility, motor development. | Every 6 mos until age 1 yr, then annually |
Ocular | Anterior chamber eval to assess for corneal clouding cataract | Annually Cardiovascular/ |
Neurovascular | Echocardiography | Every 3 yrs; More frequently in those w/abnormal echocardiogram Brain MR angiogram |
Pulmonary | Peak flow measurements or pulmonary function tests | Every 3 yrs beginning at age 8 yrs (in those who can cooperate) |
Source: GeneReviews — "Neurocutaneous Disorders due to Mitochondrial Proline Synthesis Defects"
Phenotype severity distribution: 1 always present feature, 3 very common features, 4 common features.
Estimated prevalence: <1 in 1,000,000 (VERY_RARE).
No clinical trials have been registered for hereditary spastic paraplegia 9A.
4 publications have been identified in PubMed for hereditary spastic paraplegia 9A. Research spans Gene Therapy / Novel Therapeutics (50%), Review / Meta-Analysis (25%), and Case Report / Case Series (25%).
Ziegler M (2026). [PMID: 42154535](https://pubmed.ncbi.nlm.nih.gov/42154535/). *JCI Insight*. [Gene Therapy / Novel Therapeutics]
Ziegler M (2025). [PMID: 40027661](https://pubmed.ncbi.nlm.nih.gov/40027661/). *bioRxiv*. [Gene Therapy / Novel Therapeutics]
Shan D (2025). [PMID: 40845627](https://pubmed.ncbi.nlm.nih.gov/40845627/). *Stem Cell Res*. [Case Report / Case Series]
Salari M (2025). [PMID: 40041249](https://pubmed.ncbi.nlm.nih.gov/40041249/). *Neurol Genet*. [Review / Meta-Analysis]
Data assembled from 7 of 12 sources · Last updated Sep 19, 2026, 6:55 PM UTC
Online Mendelian Inheritance in Man
European rare disease database
Genetic and Rare Diseases Info Center
Thin, translucent skin |
90% |
Visible veins |
Neurologic | Developmental delay | 98% |
Hypotonia | 93% | But often brisk reflexes in ALDH18A1-related ADCL |
Corpus callosum dysgenesis | 55% | — |
Athetoid movements | 26% | Most frequent in ALDH18A1-related ARCL |
Spastic diplegia | 10% | Only in ALDH18A1-related ADCL |
Growth | IUGR | 96% |
Postnatal growth deficiency | 85% | — |
Microcephaly | 68% | But neurocranium appears prominent |
Relative macrocephaly | 10% | Only in ALDH18A1-related ADCL |
Connective tissue/ Musculoskeletal | Joint hyperlaxity | 98% |
Osteopenia | 74% | Rarely, fractures |
Adducted thumbs/ clubfoot | 67% | — |
Congenital hip dislocation | 53% | — |
Wormian bones | 49% | — |
Hernias | 46% | — |
Enlarged fontanel w/delayed closure | 37% | — |
Dysmorphic/Progeroid | 95% | Often, prominent chin when older |
Ocular | Cataract | 58% |
Strabismus | 40% | — |
Blue sclerae | 35% | — |
Corneal clouding | 20% | Most frequent in ALDH18A1-related ARCL and ADCL; less frequent in PYCR1-related ARCL Based on , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Cutaneous features. At birth, all affected individuals have cutis laxa with some degree of skin wrinkling. |
Source: GeneReviews — "Neurocutaneous Disorders due to Mitochondrial Proline Synthesis Defects"
AR
Large neurocranium relative to viscerocranium; Aged appearance1 |
Characteristic facial features w/severely hypoplastic jaw EFEMP1(FBLN3) | EFEMP1-related cutis laxa (ARCL1D) (OMIM 620780) | AR | Translucent skin; Joint laxity2 |
EFEMP2 | EFEMP2-related cutis laxa (ARCL1B) | AR | Thin, translucent skin w/wrinkles |
EMILIN1 | Arterial tortuosity w/bone fragility syndrome (OMIM 620908) | AR | Thin, translucent skin w/wrinkles; Bone fragility3 |
FBLN5 | FBLN5-related cutis laxa (ARCL1A) | AR | Cutis laxa |
GORAB | Geroderma osteodysplasticum, GORAB-related (OMIM 231070) | AR | Generalized cutis laxa (pronounced at hands); Hip dislocation; Short stature; Aged appearance4 |
Hutchinson-Gilford progeria syndrome | AD | Translucent skin; Large neurocranium relative to viscerocranium; Aged appearance | Characteristic facial appearance; Severe growth deficiency; Atherosclerosis; Osteoporosis; Hair loss |
LOX | Arterial tortuosity w/bone fragility syndrome5 | AR | Thin, translucent skin w/wrinkles; Bone fragility |
LTBP1 | Cutis laxa w/craniosynostosis, short stature, brachydactyly, syndactyly, LTBP1-related (OMIM 619451) | AR | Short stature; Cutis laxa6 |
LTBP4-related cutis laxa (ARCL1C) | AR | Cutis laxa | Congenital emphysema; Congenital diaphragmatic hernia; Downslanted palpebral fissures; Generalized cutis laxa w/thick skin folds; Norm... |
Source: GeneReviews — "Neurocutaneous Disorders due to Mitochondrial Proline Synthesis Defects"