Microphthalmia with linear skin defects syndrome

What causes microphthalmia with linear skin defects syndrome (MLS syndrome)?

MLS syndrome is most commonly caused by mutations in the HCCS gene or a deletion of genetic material on the X chromosome that includes the HCCS gene. This gene provides instructions for a protein that is involved in many tissues of the body-particularly the mitochondria. The mitochondria are the structures in our cells that produce energy. The protein is additionally involved in the process in which damaged cells are destroyed (apoptosis). A mutations within the HCCS gene or loss of the gene entirely may lead to an issue with energy production and the ability to destroy damaged cells.

In some cases, MLS syndrome may be caused by mutations in the COX7B and NDUFB11 genes, (also located on the X chromosome).

Last updated on 05-01-20

How is microphthalmia with linear skin defects syndrome (MLS syndrome) inherited?

MLS syndrome is inherited in an X-linked manner. This means that the gene responsible for the condition is located on the X chromosome, and having only one mutated copy of the gene is enough to cause the condition. There is nothing either parent can do, before or during a pregnancy, to cause a child to have this condition.

Because males have only one X chromosome (and one Y chromosome) and females have two X chromosomes, X-linked dominant conditions affect males and females differently. Both males and females can have an X-linked dominant condition. However, because males don't have a second, working copy of the gene (as females do), they usually have more severe disease than females. Males that inherit MLS syndrome usually have very serious developmental concerns. Almost no males are born with this condition. If a mother has the mutated X-linked gene, each of her children (both male and female) has a 50% chance to inherit the mutated gene.

Most cases of MLS syndrome occur in people with no history of the disorder in their family. These cases usually result from the deletion of a piece of the X chromosome during the formation of the eggs or sperm or in early fetal development. They may also result from a new ( de novo) _mutation in the _HCCS gene.

Last updated on 05-01-20

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The RareGuru disease database is regularly updated using data generously provided by GARD, the United States Genetic and Rare Disease Information Center.

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