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Autosomal recessive cutis laxa type 2B is a rare, hereditary, developmental defect with connective tissue involvement characterized by cutis laxa of variable severity, in utero growth restriction, congenital hip dislocation and joint hyperlaxity, wrinkling of the skin, in particular the dorsum of hands and feet, and progeroid facial features. Hypotonia, developmental delay, and intellectual disability are common. In addition, cataracts, corneal clouding, wormian bones, lipodystrophy and osteopenia have been reported.
Features include always present findings: Dermal translucency, Prominent forehead, Large fontanelles, and Pes planus and others; and very common findings: Deeply set eye. 51 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Bones and joints | 5 | Joint hypermobility, Mild bone density loss (osteopenia), Sideways curvature of the spine (scoliosis) |
Skin | 4 | Redundant skin, Excessive wrinkled skin, Thin skin |
Brain and nerves | 3 | Hydrocephalus, Intellectual disability, Global developmental delay |
Head and neck | 3 | Microcephaly, Triangular face, High palate |
Growth and development | 2 | Failure to thrive, Intrauterine growth retardation |
Pregnancy and birth | 1 | Congenital hip dislocation |
Muscles | 1 | Decreased muscle mass |
Digestive system | 1 | Gastroesophageal reflux |
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% |
PYCR1 function has not been fully characterized.
Autosomal recessive cutis laxa type 2B is caused by mutations in the PYCR1 gene on chromosome 17.
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 PYCR1 is available. Testing is considered confirmatory for diagnosis.
No approved treatments are currently available for autosomal recessive cutis laxa type 2B. The disease remains an area of unmet medical need.
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 autosomal recessive cutis laxa type 2B
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: 24 always present features, 1 very common feature, 18 common features.
Estimated prevalence: <1 in 1,000,000 (VERY_RARE).
No clinical trials have been registered for autosomal recessive cutis laxa type 2B.
1 publication has been identified in PubMed for autosomal recessive cutis laxa type 2B. Research spans Case Report / Case Series (100%).
Shangguan S (2024). [PMID: 39172257](https://pubmed.ncbi.nlm.nih.gov/39172257/). *Molecular genetics and genomics : MGG*. [Case Report / Case Series]
Data assembled from 8 of 12 sources · Last updated Sep 19, 2026, 3:26 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"