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Disease Profile

Hypomyelination and congenital cataract

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

<1 / 1 000 000

US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Leukodystrophy, hypomyelinating, 5; HLD5; Hypomyelination congenital cataract


Congenital and Genetic Diseases; Eye diseases; Nervous System Diseases


Hypomyelination and congenital cataract is a very rare disease characterized by cloudy coverings of the eye that are present at birth (congenital cataracts) and neurologic impairment that becomes apparent after the first year of life. The neurologic impairment is progressive and presents as ataxia and spasticity. Affected individuals may lose the ability to walk. Signs and symptoms may vary but can include loss of sensation in the hands and feet (peripheral neuropathy), curvature of the spine (scoliosis), difficulty speaking (dysarthria), seizures, and moderate intellectual disability. Hypomyelination and congenital cataract is caused by a change (mutation ) in the FAM126A gene and is inherited in an autosomal recessive manner.[1][2][3] Diagnosis of hypomyelination and congenital cataract is based on clinical findings of muscle weakness and cataracts, and a brain MRI that indicates a loss of the myelin surrounding the neurons. The diagnosis can be confirmed by genetic testing of the FAM126A gene. Treatment is focused on relieving symptoms of the condition and may include physical therapy, special education, and medication to treat seizures.[1]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Abnormal cerebellum morphology
Abnormality of the cerebellum
Cerebellar abnormalities
Cerebellar abnormality
Cerebellar anomaly

[ more ]

Abnormal pyramidal sign
Cerebral hypomyelination
Developmental cataract
Clouding of the lens of the eye at birth
Global developmental delay
Intellectual disability, moderate
IQ between 34 and 49
Percent of people who have these symptoms is not available through HPO
Autosomal recessive inheritance
Babinski sign
Cerebral white matter atrophy
Decreased motor nerve conduction velocity
Difficulty articulating speech
Increased reflexes
Infantile onset
Onset in first year of life
Onset in infancy

[ more ]

Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific

[ more ]

Intention tremor
Loss of ability to walk
Lower limb amyotrophy
Lower limb muscle weakness
Lower extremity weakness
Lower limb weakness
Muscle weakness in lower limbs

[ more ]

Motor delay
Muscular hypotonia of the trunk
Low muscle tone in trunk
Onion bulb formation
Peripheral nerve disease
Truncal titubation
Variable expressivity


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Providing General Support

    Learn more

    These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

    Where to Start

    • Genetics Home Reference (GHR) contains information on Hypomyelination and congenital cataract. This website is maintained by the National Library of Medicine.

      In-Depth Information

      • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
      • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
      • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
      • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
      • PubMed is a searchable database of medical literature and lists journal articles that discuss Hypomyelination and congenital cataract. Click on the link to view a sample search on this topic.


        1. Biancheri R, Zara F, Bruno C, Gazzerro E, Rossi A, van der Knaap MS and Minetti C. Hypomyelination and Congenital Cataract. GeneReveiws. June 4 2015; https://www.ncbi.nlm.nih.gov/books/NBK2587/.
        2. Hypomyelination and congenital cataract. Genetics Home Reference. July 2009; https://ghr.nlm.nih.gov/condition/hypomyelination-and-congenital-cataract.
        3. Biancheri R1, Zara F, Rossi A, Mathot M, Nassogne MC, Yalcinkaya C, Erturk O, Tuysuz B, Di Rocco M, Gazzerro E, Bugiani M, van Spaendonk R, Sistermans EA, Minetti C, van der Knaap MS, and Wolf NI. Hypomyelination and congenital cataract: broadening the clinical phenotype. Arch Neurol. September 2011; 68(9):1191-4. https://www.ncbi.nlm.nih.gov/pubmed/21911699.