Megacystis microcolon intestinal hypoperistalsis syndrome

What causes megacystis microcolon intestinal hypoperistalsis syndrome?

This condition is part of a group of disorders caused by mutations in the ACTG2 gene. ACTG2-related disorders are inherited in an autosomal dominant manner.

Last updated on 05-01-20

Is megacystis microcolon intestinal hypoperistalsis syndrome inherited?

Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is inherited in an autosomal dominant manner. This means that having a change (mutation) in only one copy of the responsible gene in each cell is enough to cause features of the condition. There is nothing that either parent can do, before or during a pregnancy, to cause a child to have this condition.

In some cases, an affected person inherits the mutation from an affected parent. In other cases, the mutation occurs for the first time in a person with no family history of the condition. This is called a de novo mutation. While the exact proportion of inherited versus de novo mutations is unknown, current data suggest that de novo mutations are common.

When a person with a mutation that causes an autosomal dominant condition has children, each child has a 50% (1 in 2) chance to inherit that mutation. However, the severity of signs and symptoms can vary within a family. If the mutation in a family member with MMIHS has been identified, prenatal testing for pregnancies at increased risk is possible.

Last updated on 05-01-20

What is the age of the oldest reported person with megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS)?

In a review of the literature published in 2011 including 227 cases of megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS), the oldest survivors were a 19 year old female and 24 year old male. However the 24 year old male was only diagnosed as an adult and appeared to have a milder case. The 19 year old female however was diagnosed shortly after birth. What seems special about this case is that she had been able to remain free of infections since the age of 4 or 5 years old. In the most recent case report in 2016 which reported on 4 people with MMIHS, one was a 20 year old female survivor as well.


Last updated on 05-01-20

What is the long-term outlook for children with megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS)?

Survival in MMIHS seems to have improved, thanks to more specialized care, innovations in parenteral nutrition, and introduction of multivisceral transplantation. Long-term survival usually requires total parenteral nutrition and urinary catheterization or diversion. Most long-term survivors have ileostomies. In families with an inherited MMIHS-causing mutation, some family members with a mutation have milder features, living into adolescence and early adulthood.

While there are reports of longer survival, the prognosis and life expectancy remains poor, and it is still fatal in many cases. The main causes of death include sepsis, malnutrition, or multiple organ failure.

Last updated on 05-01-20

Name: Birth Defect Research for Children, Inc. 976 Lake Baldwin Lane, Suite 104
Orlando, FL, 32814, United States
Phone: +1-407-895-0802 Email: staff@birthdefects.org Url: https://www.birthdefects.org/
Name: MMIHS.org United States Url: http://www.mmihs.org/ Parent based organization. Offers several resources.

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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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