Acromicric dysplasia

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What is acromicric dysplasia?

Acromicric dysplasia is a condition characterized by severely short stature, short limbs, stiff joints, and distinctive facial features.

Newborns with acromicric dysplasia are of normal size, but slow growth over time results in short stature. The average height of adults with this disorder is about 4 feet, 2 inches for women and 4 feet, 5 inches for men. The long bones of the arms and legs, and the bones in the hands and feet, are shorter than would be expected for the individual's height. Other skeletal features that occur in this disorder include slowed mineralization of bone (delayed bone age), abnormally shaped bones of the spine (vertebrae), and constrained movement of joints. Affected individuals often develop carpal tunnel syndrome, which is characterized by numbness, tingling, and weakness in the hands and fingers. A misalignment of the hip joints (hip dysplasia) can also occur in this disorder. These skeletal and joint problems may require treatment, but most affected individuals have few limitations in their activities.

Children with acromicric dysplasia may have a round face, sharply defined eyebrows, long eyelashes, a bulbous nose with upturned nostrils, a long space between the nose and upper lip (philtrum), and a small mouth with thick lips. These facial differences become less apparent in adulthood. Intelligence is unaffected in this disorder, and life expectancy is generally normal.

How common is acromicric dysplasia?

Acromicric dysplasia is a rare disorder; its prevalence is unknown.

What genes are related to acromicric dysplasia?

Acromicric dysplasia is caused by mutations in the FBN1 gene, which provides instructions for making a large protein called fibrillin-1. This protein is transported out of cells into the extracellular matrix, which is an intricate lattice of proteins and other molecules that forms in the spaces between cells. In this matrix, molecules of fibrillin-1 attach (bind) to each other and to other proteins to form threadlike filaments called microfibrils. The microfibrils become part of the fibers that provide strength and flexibility to connective tissues, which support the bones, skin, and other tissues and organs. Additionally, microfibrils store molecules called growth factors, including transforming growth factor beta (TGF-β), and release them at various times to control the growth and repair of tissues and organs throughout the body.

Most of the FBN1 gene mutations that cause acromicric dysplasia change single protein building blocks in the fibrillin-1 protein. The mutations result in a reduction and disorganization of the microfibrils. Without enough normal microfibrils to store TGF-β, the growth factor is abnormally active. These effects likely contribute to the physical abnormalities that occur in acromicric dysplasia, but the mechanisms are unclear.

How do people inherit acromicric dysplasia?

Acromicric dysplasia is an autosomal dominant condition, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Most cases result from new mutations in the gene and occur in people with no history of the disorder in their family. In other cases, an affected person inherits the mutation from one affected parent.

Where can I find information about diagnosis or management of acromicric dysplasia?

These resources address the diagnosis or management of acromicric dysplasia and may include treatment providers.

Genetic Testing Registry: Acromicric dysplasia

You might also find information on the diagnosis or management of acromicric dysplasia inEducational resources and Patient support.

General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.

To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.

Where can I find additional information about acromicric dysplasia?

You may find the following resources about acromicric dysplasia helpful. These materials are written for the general public.

MedlinePlus - Health information
Genetic and Rare Diseases Information Center - Information about genetic conditions and rare diseases
Educational resources - Information pages (4 links)
Patient support - For patients and families (4 links)

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

Genetic Testing Registry - Repository of genetic test information (1 link)
PubMed - Recent literature
OMIM - Genetic disorder catalog

What other names do people use for acromicric dysplasia?

ACMICD

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines and How are genetic conditions and genes named? in the Handbook.

What if I still have specific questions about acromicric dysplasia?

Ask the Genetic and Rare Diseases Information Center

Where can I find general information about genetic conditions?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding acromicric dysplasia?

autosomal ; autosomal dominant ; carpal tunnel syndrome ; cell ; dysplasia ; extracellular ;extracellular matrix ; gene ; growth factor ; joint ; microfibrils ; mutation ; philtrum ; prevalence ;protein ; short stature ; stature ; syndrome

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

References (3 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.