Macrocephaly-capillary malformation

A genetic disorder characterized by overgrowth and vascular anomalies

Macrocephaly-capillary malformation

Macrocephaly-capillary malformation (M-CM) is a rare genetic disorder characterized by a combination of macrocephaly, capillary malformation, and other distinctive features. It is also known as macrocephaly-capillary malformation syndrome (M-CM syndrome) or macrocephaly-cutis marmorata telangiectatica congenita (M-CMTC).

Clinical Features

Individuals with M-CM typically present with a range of clinical features, which may vary in severity. The hallmark features include:

• Macrocephaly: An abnormally large head size, often present at birth or developing in early infancy.
• Capillary malformations: These are flat, pink or red birthmarks, often referred to as "port-wine stains," that can occur anywhere on the body.
• Overgrowth: Disproportionate overgrowth of one side of the body (hemihyperplasia) or generalized overgrowth.
• Developmental delay: Many individuals experience delays in reaching developmental milestones.
• Hypotonia: Decreased muscle tone, which can affect motor skills.
• Syndactyly: Fusion of fingers or toes, which may be partial or complete.
• Polydactyly: Extra fingers or toes.
• Connective tissue abnormalities: Such as joint hypermobility or skin laxity.

Genetics

M-CM is caused by mutations in the PIK3CA gene, which plays a role in cell growth and division. These mutations are typically not inherited but occur as a de novo event, meaning they arise spontaneously in the affected individual. The condition is part of a group of disorders known as PIK3CA-related overgrowth spectrum (PROS).

Diagnosis

Diagnosis of M-CM is based on clinical evaluation and the presence of characteristic features. Genetic testing can confirm the diagnosis by identifying mutations in the PIK3CA gene. Imaging studies, such as MRI or CT scan, may be used to assess brain structure and identify any associated abnormalities.

Management

There is no cure for M-CM, and treatment is symptomatic and supportive. Management may involve:

• Regular monitoring of head growth and development.
• Physical and occupational therapy to address motor delays and hypotonia.
• Surgical intervention for syndactyly or polydactyly if necessary.
• Educational support for developmental delays.
• Monitoring for potential complications, such as seizures or hydrocephalus.

Prognosis

The prognosis for individuals with M-CM varies depending on the severity of symptoms and associated complications. Early intervention and supportive therapies can improve quality of life and developmental outcomes.

Related pages

• Genetic disorder
• Overgrowth syndrome
• PIK3CA-related overgrowth spectrum
• Capillary malformation