NNT - nicotinamide nucleotide transhydrogenase - Genetics Home Reference

NNT - nicotinamide nucleotide transhydrogenase - Genetics Home Reference

NNT

On this page:

 

• Name 
• Normal function 
• Genetic changes 
• Gene location 
• Additional information
• Other names 
• About genes 
• Glossary definitions

What is the official name of the NNT gene?

The official name of this gene is “nicotinamide nucleotide transhydrogenase.”

NNT is the gene's official symbol. The NNT gene is also known by other names, listed below.

Read more about gene names and symbols on the About page.

What is the normal function of the NNT gene?

The NNT gene provides instructions for making an enzyme called nicotinamide nucleotide transhydrogenase. This enzyme is found embedded in the inner membrane of structures called mitochondria, which are the energy-producing centers of cells. This enzyme helps produce a substance called NADPH, which is involved in removing potentially toxic molecules called reactive oxygen species that can damage DNA, proteins, and cell membranes. Nicotinamide nucleotide transhydrogenase is found throughout the body, but it is particularly abundant in the hormone-producing adrenal and thyroid glands, heart, kidneys, and fatty tissue.

How are changes in the NNT gene related to health conditions?

familial glucocorticoid deficiency - caused by mutations in the NNT gene

At least 25 mutations in the NNT gene have been found to cause familial glucocorticoid deficiency. This condition is characterized by potentially life-threatening low blood sugar (hypoglycemia), recurrent infections, and skin coloring darker than that of other family members (hyperpigmentation). The features of familial glucocorticoid deficiency are caused by an inability of the adrenal glands to produce a group of hormones called glucocorticoids, which play a role in many functions in the body. NNT gene mutations account for approximately 10 percent of cases of this condition.

Most of the mutations that cause familial glucocorticoid deficiency change single protein building blocks (amino acids) in the nicotinamide nucleotide transhydrogenase enzyme. These mutations impair the enzyme's ability to produce NADPH, leading to an increase in reactive oxygen species in the adrenal glands. Over time, these toxic molecules can impair the function of adrenal gland cells and lead to the death of those cells (apoptosis), diminishing the production of glucocorticoids. A shortage of these hormones impairs blood sugar regulation, immune system function, and other cellular functions, leading to the signs and symptoms of familial glucocorticoid deficiency.

It is unclear why NNT gene mutations seem to only affect adrenal gland function. Researchers suggest that individuals with familial glucocorticoid deficiency caused by NNT gene mutations could develop problems in other tissues over time as reactive oxygen species exert their harmful effects.

Where is the NNT gene located?

Cytogenetic Location: 5p12

Molecular Location on chromosome 5: base pairs 43,602,688 to 43,705,565

The NNT gene is located on the short (p) arm of chromosome 5 at position 12.

More precisely, the NNT gene is located from base pair 43,602,688 to base pair 43,705,565 on chromosome 5.

See How do geneticists indicate the location of a gene? in the Handbook.

Where can I find additional information about NNT?

You and your healthcare professional may find the following resources about NNT helpful.

• Genetic Testing Registry - Repository of genetic test information (1 link)

You may also be interested in these resources, which are designed for genetics professionals and researchers.

• PubMed - Recent literature
• OMIM - Genetic disorder catalog
• Research Resources - Tools for researchers (4 links)

What other names do people use for the NNT gene or gene products?

• energy-linked transhydrogenase
• GCCD4
• NADPH transferase
• NADP transhydrogenase
• NAD(P) transhydrogenase
• NAD(P) transhydrogenase, mitochondrial
• nicotinamide adenine dinucleotide phosphate + transhydrogenase
• NNTM_HUMAN
• pyridine nucleotide transhydrogenase

See How are genetic conditions and genes named? in the Handbook.

Where can I find general information about genes?

The Handbook provides basic information about genetics in clear language.

• What is DNA?
• What is a gene?
• How do genes direct the production of proteins?
• How can gene mutations affect health and development?

These links provide additional genetics resources that may be useful.

• Genetics Education
• Human Genome Project
• Resources for Genetics Researchers

What glossary definitions help with understanding NNT?

acids ; adenine ; adrenal cortex ; adrenal glands ; apoptosis ; cell ; deficiency ; DNA ; enzyme ;familial ; fatty tissue ; gene ; glucocorticoid ; glucocorticoids ; glutathione ; hormone ;hypoglycemia ; immune system ; mitochondria ; nucleotide ; oxygen ; phosphate ; protein ;reactive oxygen species ; thyroid ; tissue ; toxic ; transferase

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

See also Understanding Medical Terminology.

References (5 links)

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook