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Disease Profile

Methylcobalamin deficiency cbl G type

Prevalence
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

< 331

US Estimated

< 514

Europe Estimated

Age of onset

All ages

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ICD-10

E72.1

Inheritance

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

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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

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X-linked
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.

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

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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.

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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.

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Not applicable

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Other names (AKA)

Homocystinuria-megaloblastic anemia, cblG complementation type; cblG; Methionine synthase deficiency

Categories

Blood Diseases; Congenital and Genetic Diseases; Kidney and Urinary Diseases;

Summary

Methylcobalamin deficiency cbl G type is a rare condition that occurs when the body is unable to process certain amino acids (building blocks of protein) properly. In most cases, signs and symptoms develop during the first year of life; however, the age of onset can range from infancy to adulthood. Common features of the condition include feeding difficulties, lethargy, seizures, poor muscle tone (hypotonia), developmental delay, microcephaly (unusually small head size), and megaloblastic anemia. Methylcobalamin deficiency cbl G type is caused by changes (mutations) in the MTR gene and is inherited in an autosomal recessive manner. Treatment generally includes regular doses of hydroxocobalamin (vitamin B12). Some affected people may also require supplementation with folates and betaine.[1][2]

Symptoms

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:
HPO ID
5%-29% of people have these symptoms
Blindness
0000618
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Percent of people who have these symptoms is not available through HPO
Autosomal recessive inheritance
0000007
Cerebral atrophy
Degeneration of cerebrum
0002059
Decreased methionine synthase activity
0003524
Decreased methylcobalamin
0003223
Failure to thrive
Faltering weight
Weight faltering

[ more ]

0001508
Feeding difficulties in infancy
0008872
Gait disturbance
Abnormal gait
Abnormal walk
Impaired gait

[ more ]

0001288
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

0001290
Global developmental delay
0001263
Homocystinuria
High urine homocystine levels
0002156
Hyperhomocystinemia
Elevated blood homocystine
0002160
Hypomethioninemia
Decreased plasma methionine
Decreased serum methionine

[ more ]

0003658
Infantile onset
Onset in first year of life
Onset in infancy

[ more ]

0003593
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation

[ more ]

0001249
Megaloblastic anemia
0001889
Poor coordination
0002370
Seizure
0001250

Diagnosis

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

    Organizations

    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 Supporting this Disease

      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 Methylcobalamin deficiency cbl G type. 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 Methylcobalamin deficiency cbl G type. Click on the link to view a sample search on this topic.

          References

          1. Nuria Carrillo-Carrasco, MD, David Adams, MD, PhD, and Charles P Venditti, MD, PhD. Disorders of Intracellular Cobalamin Metabolism. GeneReviews. November 2013; https://www.ncbi.nlm.nih.gov/books/NBK1328/.
          2. Homocystinuria without methylmalonic aciduria. Orphanet. March 2012; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=622.