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X-linked intellectual disability, Cabezas type is characterized by intellectual deficit, muscle wasting, short stature, a prominent lower lip, small testes, kyphosis and joint hyperextensibility. An abnormal gait, tremor, decreased fine motor coordination and impaired speech are also present. The syndrome has been described in six boys from three generations of the same family. Transmission is X-linked and the causative gene has been localized to the q24-q25 region of the X chromosome.
Features include always present findings: Intellectual disability, Motor delay, and Delayed speech and language development; and very common findings: Hyperactivity, Absent speech, Wide mouth, and Small hand and others. 81 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Brain and nerves | 15 | Seizure, Gait ataxia, Aggressive behavior |
Head and neck | 7 | Relative macrocephaly, Coarse facial features, Thick lower lip vermilion |
Arms and legs | 6 | Short foot, Small hand, Distal lower limb amyotrophy |
Muscles | 3 | Low muscle tone (hypotonia), Generalized hypotonia, Cerebellar vermis atrophy |
Bones and joints | 3 | Joint hypermobility, Excessive outward curvature of the upper spine (kyphosis), Sideways curvature of the spine (scoliosis) |
Growth and development | 2 | Short stature, Cachexia |
Hormones | 2 | Hypogonadism, Delayed puberty |
Digestive system | 1 | Abdominal obesity |
Skin | 1 | Excessive sweating (hyperhidrosis) |
Blood and immune system | 1 | Immunodeficiency |
CUL4B encodes cullin 4B (913 aa). Core component of multiple cullin-RING-based E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins. Highest expression in Cells Cultured fibroblasts (95.9 TPM) and Cervix Endocervix (45.3 TPM).
X-linked intellectual disability, Cabezas type is caused by mutations in the CUL4B gene on chromosome X.
The CUL4B protein participates in Global Genome Nucleotide Excision Repair (GG-NER), Nucleotide Excision Repair, and Transcription-Coupled Nucleotide Excision Repair (TC-NER) pathways.
CUL4B is classified as a druggable target (Enzyme category) with score 0.0.
Genetic testing for CUL4B is available. Testing is considered confirmatory for diagnosis.
Biomarker and diagnostic research for X-linked intellectual disability, Cabezas type has been reported in the published literature.
Phenotype severity distribution: 3 always present features, 20 very common features, 19 common features.
Estimated prevalence: <1 in 1,000,000 (VERY_RARE).
No clinical trials have been registered for X-linked intellectual disability, Cabezas type.
2 publications have been identified in PubMed for X-linked intellectual disability, Cabezas type. Research spans Diagnostic / Biomarker (50%) and Case Report / Case Series (50%).
Arora K (2025). [PMID: 40117183](https://pubmed.ncbi.nlm.nih.gov/40117183/). *Ann Indian Acad Neurol*. [Diagnostic / Biomarker]
Lin L (2025). [PMID: 40761315](https://pubmed.ncbi.nlm.nih.gov/40761315/). *Front Neurosci*. [Case Report / Case Series]
Data assembled from 7 of 12 sources · Last updated Sep 19, 2026, 5:36 AM UTC
Online Mendelian Inheritance in Man
European rare disease database
Genetic and Rare Diseases Info Center
Common questions about X-linked intellectual disability, Cabezas type