What are the other Names for this Condition? (Also known as/Synonyms)

• Muscle-Liver-Brain-Eye Nanism
• Perheentupa Syndrome
• Pericardial Constriction and Growth Failure

What is Mulibrey Nanism? (Definition/Background Information)

• Mulibrey Nanism (MN) is a rare genetic disorder characterized by profound growth delays and distinctive abnormalities of the muscles, liver, brain, and eyes
• The acronym MULIBREY stands for (MU)scle, (LI)ver, (BR)ain, and (EY)e; nanism is another word for dwarfism
• Signs and symptoms of the disorder may include constrictive pericarditis; low birth weight; short stature; severe progressive growth delays; hypotonia; hepatomegaly; and yellow discoloration of the eyes in infancy
• It is caused by mutations in the TRIM37 gene and is inherited in an autosomal recessive manner
• Treatment may include surgery for constrictive pericarditis, medications for progressive heart failure and hormone replacement therapy

(Source: Mulibrey Nanism; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Mulibrey Nanism? (Age and Sex Distribution)

• Mulibrey Nanism is a rare congenital disorder. The presentation of symptoms may occur at birth
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Mulibrey Nanism? (Predisposing Factors)

• A positive family history may be an important risk factor, since Mulibrey Nanism is an inherited condition

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Mulibrey Nanism? (Etiology)

• Mulibrey Nanism is caused by mutations in the TRIM37 gene and is inherited in an autosomal recessive manner

(Source: Mulibrey Nanism; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Autosomal recessive: Autosomal recessive conditions are traits or disorders that occur when two copies of an abnormal gene have been inherited on a non-sex chromosome. If both parents have an autosomal recessive condition, there is a 100% likelihood of passing on the mutated genes to their children. If, however, only one mutant copy of the gene is inherited, the individual will be a carrier of the condition, but will not be present with any symptoms. Children born to two carriers, have a 25% chance of being homozygous dominant (unaffected), a 50% chance of being heterozygous (carrier), and a 25% chance of being homozygous recessive (affected).

What are the Signs and Symptoms of Mulibrey Nanism?

Mulibrey Nanism (MN) is characterized by progressive growth failure that begins prenatally (before birth).

• Hypotonia (poor muscle tone) is common
• Newborns often have characteristic abnormalities of the head and face, including a triangularly shaped face
• Yellow discoloration of the eyes and other ocular abnormalities may be present, but vision is usually normal
• More than 90% of affected individuals have a J-shaped sella turcica, which is a depression in the sphenoid bone at the base of the skull. Infants with Mulibrey Nanism may also have symptoms related to overgrowth of the fibrous sac surrounding the heart (constrictive pericarditis)
• When constrictive pericarditis is present at birth, affected infants may have a bluish discoloration of the skin (cyanosis), especially on the lips and fingertips
• Individuals with MN typically have a high-pitched voice

Other symptoms may include abnormally prominent veins in the neck, congestion in the lungs, abnormal fluid accumulation in the abdomen (ascites), swelling of the arms and/or legs (peripheral edema), and/or enlargement of the heart (cardiac hypertrophy) and/or liver (hepatomegaly).

• There may also be elevated pressure in the veins, congestion or blockage in the main artery serving the lungs (pulmonary artery), and/or a build-up of fibrous tissue in the walls of the lungs (pulmonary fibrosis)
• Associated complications of these conditions may lead to congestive heart failure
• In some cases, individuals with Mulibrey Nanism may have additional physical abnormalities, such as an unusually thin shinbone (fibrous tibia dysplasia). Large cerebral ventricles in the brain and delayed motor development are uncommon findings
• Most affected individuals have normal intelligence. Individuals with Mulibrey Nanism often have underdevelopment of various endocrine glands, that leads to hormone deficiencies

Very frequently present symptoms in 80-99% of the cases:

• Cachexia
• High pitched voice
• Intrauterine growth retardation
• J-shaped sella turcica
• Macrocephaly

Frequently present symptoms in 30-79% of the cases:

• Hepatomegaly
• Wide nasal bridge

Some signs and symptoms of Mulibrey Nanism include:

• Delayed puberty sometimes occurs, accompanied by infrequent or very light menstrual periods
• Absent frontal sinuses
• Astigmatism
• Congestive heart failure
• Dental crowding
• Dolichocephaly
• Dysarthria
• Frontal bossing
• Hypertelorism
• Hypodontia
• Hypoplastic frontal sinuses
• Microglossia
• Muscular hypotonia
• Myocardial fibrosis
• Nephroblastoma
• Nevus
• Pericardial constriction
• Pigmentary retinopathy
• Strabismus
• Triangular face
• Ventriculomegaly
• Weak voice

(Source: Mulibrey Nanism; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Mulibrey Nanism Diagnosed?

• Testing for the TRIM37 gene is available for carrier testing, confirming the diagnosis, and prenatal diagnosis of Mulibrey Nanism

(Source: Mulibrey Nanism; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Mulibrey Nanism?

The complications of Mulibrey Nanism may include:

• Wasting syndrome or cachexia
• Severe heart abnormalities
• Severe liver dysfunction

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Mulibrey Nanism Treated?

• Treatment may include surgery for constrictive pericarditis, medications for progressive heart failure and hormone replacement therapy

(Source: Mulibrey Nanism; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How can Mulibrey Nanism be Prevented?

Currently, Mulibrey Nanism may not be preventable, since it is a genetic disorder.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Mulibrey Nanism? (Outcomes/Resolutions)

• Differences in the nature and severity of the wide range of abnormalities and complications make it difficult to predict the course of the disorder in any one individual
• Some individuals may be more mildly affected, while others experience severe complications
• Episodes of respiratory failure induced by an infection, as well as congestive heart failure, have occurred in infants (in addition to older individuals) with the disorder and may cause early death
• It has been suggested that constrictive pericarditis with restrictive cardiomyopathy, when present, plays a large part in the prognosis
• Because the heart involvement is critical for the prognosis, early diagnosis is usually of major importance

(Source: Mulibrey Nanism; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Additional and Relevant Useful Information for Mulibrey Nanism:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/diseases-conditions/rare-disorders/