The SLC39A7 gene provides the blueprint for a protein that performs a distinct function within our cells. This gene is also known by another name, ZIP7, which is often used in scientific literature. It is part of a larger family of 14 related genes that all contribute to a particular aspect of cellular function. The information encoded in SLC39A7 dictates the structure and the job of the protein it builds.
The Role of the SLC39A7 Gene
The primary instruction provided by the SLC39A7 gene is for the creation of a protein called Zinc Transporter 7, or ZIP7. This protein’s job is to transport the mineral zinc, and its location within the cell is carefully managed. The ZIP7 protein is a transmembrane protein, meaning it is embedded within the membrane of a specific cellular compartment.
This compartment is known as the Endoplasmic Reticulum, or ER. The ER is a complex network of membranes where many of the cell’s proteins are built and folded into their correct shapes. The ZIP7 protein is situated in the membrane of this compartment. Its specific function is to control the movement of zinc ions, allowing them to pass from inside the ER out into the main volume of the cell, an area called the cytosol.
This release of zinc from the ER into the cytosol is a regulated event. The ZIP7 protein must be activated through a process called phosphorylation. This movement of zinc is important for maintaining a stable environment within the ER. If this process is disrupted, it can lead to a condition known as ER stress, where unfolded or misfolded proteins accumulate, impairing its function. Proper zinc transport by ZIP7 helps ensure that other proteins are folded correctly and that cellular signaling pathways can operate.
Associated Genetic Conditions
When the SLC39A7 gene contains mutations, it can lead to a rare, inherited disorder known as Spondylo-cheiro-dysplastic Ehlers-Danlos Syndrome (SCD-EDS). This condition affects the body’s connective tissues, which provide structure and support to skin, bones, joints, and other organs.
The term “Spondylo-” refers to the spine. Individuals with this condition often have skeletal abnormalities, including a form of spinal curvature known as kyphoscoliosis and flattened vertebrae, a condition called platyspondyly. This results in short stature that becomes progressively more apparent during childhood. Other effects include widened areas at the ends of long bones and a general reduction in bone density, or osteopenia.
“Cheiro-” is a term that relates to the hands, which have a distinctive appearance in individuals with SCD-EDS. The hands often feature slender, tapering fingers and finely wrinkled skin on the palms. Another characteristic is the atrophy, or wasting, of the thenar muscles.
Finally, “Ehlers-Danlos Syndrome” points to the broader issues with connective tissue. This aspect of the condition manifests as joint hypermobility, where the joints are unusually loose and have an increased range of movement, particularly in the hands and feet. The skin is also affected, typically being soft, doughy, and mildly hyperextensible, meaning it can be stretched more than normal.
The Connection to Broader Health Issues
Beyond its link to SCD-EDS, the SLC39A7 gene and its protein product, ZIP7, are involved in other biological systems. The proper regulation of zinc within cells is a component of a healthy immune response. Zinc acts as an intracellular signaling molecule for immune cells, influencing processes like cytokine production and the proliferation of T-cells.
The SLC39A7 gene, by controlling zinc release from the ER, has a role in the development and function of specific immune cells. Studies have identified that mutations in this gene can lead to a condition characterized by an absence of B cells. The ZIP7 protein’s function is required for proper B cell receptor signaling, a process that allows these immune cells to develop and respond to threats correctly. Research has also shown that ZIP7 supports the function of macrophages, another type of immune cell, in their ability to engulf pathogens.
The cellular processes regulated by ZIP7 have drawn attention in the context of cancer research. The signaling pathways that are influenced by zinc release from the ER are the same pathways that control cell growth and proliferation. In certain types of cancer, such as breast cancer, an elevated expression of the ZIP7 protein has been observed. This increased activity is thought to contribute to the growth and survival of cancer cells and may even play a role in the development of resistance to treatments like tamoxifen.
Diagnosis and Management
Diagnosing Spondylo-cheiro-dysplastic Ehlers-Danlos Syndrome (SCD-EDS) begins with a thorough clinical examination. A specialist, often a medical geneticist, will assess the physical features of the individual, looking for the characteristic combination of symptoms. These include short stature, specific skeletal abnormalities visible on radiological imaging, and the distinctive features of the hands and skin. The presence of major criteria, such as progressive short stature and muscle hypotonia, combined with minor criteria like soft skin and delayed motor development, helps guide the diagnostic process.
While a physical evaluation can strongly suggest SCD-EDS, a definitive diagnosis requires molecular genetic testing. This testing identifies disease-causing mutations within the SLC39A7 gene. Finding such a mutation confirms the diagnosis and can also be used for prenatal diagnosis in families with a known history of the condition. Genetic counseling is an important step for families, providing information about the autosomal recessive inheritance pattern of the disorder.
There is currently no cure that addresses the underlying genetic cause of SCD-EDS, so management focuses entirely on addressing the symptoms and improving quality of life. This requires a multidisciplinary team of healthcare professionals. Physical and occupational therapy are central to managing joint instability and muscle weakness. Regular monitoring by specialists, such as orthopedists for skeletal issues and ophthalmologists for potential eye complications like keratoconus, is also necessary.