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Megalencephaly-capillary malformation-polymicrogyria syndrome(MCAP)

MedGen UID:
355421
Concept ID:
C1865285
Disease or Syndrome
Synonyms: Macrocephaly cutis marmorata telangiectatica congenita; MACROCEPHALY-CAPILLARY MALFORMATION; Macrocephaly-capillary malformation syndrome (M-CM, MCAP); MCAP; Megalencephaly cutis marmorata telangiectatica congenita; Megalencephaly-Capillary Malformation (MCAP) Syndrome; MEGALENCEPHALY-CAPILLARY MALFORMATION SYNDROME; Megalencephaly-Capillary Malformation Syndrome (MCAP Syndrome); MEGALENCEPHALY-CAPILLARY MALFORMATION-POLYMICROGYRIA SYNDROME, SOMATIC; Megalocephaly cutis marmorata telangiectatica congenita
SNOMED CT: M-CM (Macrocephaly-capillary malformation) (700063005); Macrocephaly-capillary malformation (700063005); Macrocephaly-cutis marmorata telangiectatica congenita (700063005); Megalencephaly, capillary malformation, polymicrogyria syndrome (700063005); Megalencephaly capillary malformation (700063005); MCAP - megalencephaly capillary malformation (700063005)
Modes of inheritance:
Not genetically inherited
MedGen UID:
988794
Concept ID:
CN307044
Finding
Source: Orphanet
clinical entity without genetic inheritance.
 
Gene (location): PIK3CA (3q26.32)
 
Monarch Initiative: MONDO:0011240
OMIM®: 602501
Orphanet: ORPHA60040

Disease characteristics

Excerpted from the GeneReview: PIK3CA-Related Overgrowth Spectrum
PIK3CA-related overgrowth spectrum (PROS) encompasses a range of clinical findings in which the core features are congenital or early-childhood onset of segmental/focal overgrowth with or without cellular dysplasia. Prior to the identification of PIK3CA as the causative gene, PROS was separated into distinct clinical syndromes based on the tissues and/or organs involved (e.g., MCAP [megalencephaly-capillary malformation] syndrome and CLOVES [congenital lipomatous asymmetric overgrowth of the trunk, lymphatic, capillary, venous, and combined-type vascular malformations, epidermal nevi, skeletal and spinal anomalies] syndrome). The predominant areas of overgrowth include the brain, limbs (including fingers and toes), trunk (including abdomen and chest), and face, all usually in an asymmetric distribution. Generalized brain overgrowth may be accompanied by secondary overgrowth of specific brain structures resulting in ventriculomegaly, a markedly thick corpus callosum, and cerebellar tonsillar ectopia with crowding of the posterior fossa. Vascular malformations may include capillary, venous, and less frequently, arterial or mixed (capillary-lymphatic-venous or arteriovenous) malformations. Lymphatic malformations may be in various locations (internal and/or external) and can cause various clinical issues, including swelling, pain, and occasionally localized bleeding secondary to trauma. Lipomatous overgrowth may occur ipsilateral or contralateral to a vascular malformation, if present. The degree of intellectual disability appears to be mostly related to the presence and severity of seizures, cortical dysplasia (e.g., polymicrogyria), and hydrocephalus. Many children have feeding difficulties that are often multifactorial in nature. Endocrine issues affect a small number of individuals and most commonly include hypoglycemia (largely hypoinsulinemic hypoketotic hypoglycemia), hypothyroidism, and growth hormone deficiency. [from GeneReviews]
Authors:
Ghayda Mirzaa  |  John M Graham  |  Kim Keppler-Noreuil   view full author information

Additional descriptions

From OMIM
Megalencephaly-capillary malformation-polymicrogyria syndrome (MCAP) is characterized by a spectrum of anomalies including primary megalencephaly, prenatal overgrowth, brain and body asymmetry, cutaneous vascular malformations, digital anomalies consisting of syndactyly with or without postaxial polydactyly, connective tissue dysplasia involving the skin, subcutaneous tissue, and joints, and cortical brain malformations, most distinctively polymicrogyria (summary by Mirzaa et al., 2012). This disorder is also known as the macrocephaly-capillary malformation (MCM) syndrome (Conway et al., 2007). Mirzaa et al. (2012) suggested use of the term MCAP rather than MCM to reflect the very large brain size, rather than simply large head size, that characterizes this syndrome, and the importance and high frequency of perisylvian polymicrogyria.  http://www.omim.org/entry/602501
From MedlinePlus Genetics
Megalencephaly-capillary malformation syndrome (MCAP) is a disorder characterized by overgrowth of several tissues in the body. Its primary features are a large brain (megalencephaly) and abnormalities of small blood vessels in the skin called capillaries (capillary malformations).

In individuals with MCAP, megalencephaly leads to an unusually large head size (macrocephaly), which is typically evident at birth. After birth, the brain and head continue to grow at a fast rate for the first few years of life; then, the growth slows to a normal rate, although the head remains larger than average. Additional brain abnormalities are common in people with MCAP; these can include excess fluid within the brain (hydrocephalus) and abnormalities in the brain's structure, such as those known as Chiari malformation and polymicrogyria. Abnormal brain development leads to intellectual disability in most affected individuals and can also cause seizures or weak muscle tone (hypotonia). In particular, polymicrogyria is associated with speech delays and difficulty chewing and swallowing.

The capillary malformations characteristic of MCAP are composed of enlarged capillaries that increase blood flow near the surface of the skin. These malformations usually look like pink or red spots on the skin. In most affected individuals, capillary malformations occur on the face, particularly the nose, the upper lip, and the area between the nose and upper lip (the philtrum). In other people with MCAP, the malformations appear as patches spread over the body or as a reddish net-like pattern on the skin (cutis marmorata).

In some people with MCAP, excessive growth affects not only the brain but other individual parts of the body, which is known as segmental overgrowth. This can lead to one arm or leg that is bigger or longer than the other or a few oversized fingers or toes. Some affected individuals have fusion of the skin between two or more fingers or toes (cutaneous syndactyly).

Additional features of MCAP can include flexible joints and skin that stretches easily. Some affected individuals are said to have doughy skin because the tissue under the skin is unusually thick and soft.

The gene involved in MCAP is also associated with several types of cancer. Only a small number of individuals with MCAP have developed tumors (in particular, a childhood form of kidney cancer known as Wilms tumor and noncancerous tumors in the nervous system known as meningiomas).  https://medlineplus.gov/genetics/condition/megalencephaly-capillary-malformation-syndrome

Clinical features

From HPO
Leukemia
MedGen UID:
9725
Concept ID:
C0023418
Neoplastic Process
A cancer of the blood and bone marrow characterized by an abnormal proliferation of leukocytes.
Nephroblastoma
MedGen UID:
10221
Concept ID:
C0027708
Neoplastic Process
The presence of a nephroblastoma, which is a neoplasm of the kidney that primarily affects children.
Syndactyly
MedGen UID:
52619
Concept ID:
C0039075
Congenital Abnormality
Webbing or fusion of the fingers or toes, involving soft parts only or including bone structure. Bony fusions are referred to as "bony" syndactyly if the fusion occurs in a radio-ulnar axis. Fusions of bones of the fingers or toes in a proximo-distal axis are referred to as "symphalangism".
Polydactyly
MedGen UID:
57774
Concept ID:
C0152427
Congenital Abnormality
A congenital anomaly characterized by the presence of supernumerary fingers or toes.
Ventricular septal defect
MedGen UID:
42366
Concept ID:
C0018818
Congenital Abnormality
A hole between the two bottom chambers (ventricles) of the heart. The defect is centered around the most superior aspect of the ventricular septum.
Overgrowth
MedGen UID:
376550
Concept ID:
C1849265
Finding
Excessive postnatal growth which may comprise increased weight, increased length, and/or increased head circumference.
Large earlobe
MedGen UID:
334979
Concept ID:
C1844573
Finding
Increased volume of the earlobe, that is, abnormally prominent ear lobules.
Hydrocephalus
MedGen UID:
9335
Concept ID:
C0020255
Disease or Syndrome
Hydrocephalus is an active distension of the ventricular system of the brain resulting from inadequate passage of CSF from its point of production within the cerebral ventricles to its point of absorption into the systemic circulation.
Meningioma
MedGen UID:
7532
Concept ID:
C0025286
Neoplastic Process
The presence of a meningioma, i.e., a benign tumor originating from the dura mater or arachnoid mater.
Seizure
MedGen UID:
20693
Concept ID:
C0036572
Sign or Symptom
A seizure is an intermittent abnormality of nervous system physiology characterised by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.
Megalencephaly
MedGen UID:
65141
Concept ID:
C0221355
Congenital Abnormality
Diffuse enlargement of the entire cerebral hemispheres leading to macrocephaly (with or without overlying cortical dysplasia).
Polymicrogyria
MedGen UID:
78605
Concept ID:
C0266464
Congenital Abnormality
Polymicrogyria is a congenital malformation of the cerebral cortex characterized by abnormal cortical layering (lamination) and an excessive number of small gyri (folds).
Global developmental delay
MedGen UID:
107838
Concept ID:
C0557874
Finding
A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.
Cavum septum pellucidum
MedGen UID:
327087
Concept ID:
C1840380
Finding
If the two laminae of the septum pellucidum are not fused then a fluid-filled space or cavum is present. The cavum septum pellucidum is present at birth but usually obliterates by the age of 3 to 6 months. It is up to 1cm in width and the walls are parallel. It is an enclosed space and is not part of the ventricular system or connected with the subarachnoid space.
Ventriculomegaly
MedGen UID:
480553
Concept ID:
C3278923
Finding
An increase in size of the ventricular system of the brain.
Intellectual disability
MedGen UID:
811461
Concept ID:
C3714756
Mental or Behavioral Dysfunction
Subnormal intellectual functioning which originates during the developmental period. Intellectual disability, previously referred to as mental retardation, has been defined as an IQ score below 70.
Hernia
MedGen UID:
6816
Concept ID:
C0019270
Finding
The protrusion of part of an organ or fibroadipose tissue through an abnormal opening.
Hypotonia
MedGen UID:
10133
Concept ID:
C0026827
Finding
Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.
Joint laxity
MedGen UID:
39439
Concept ID:
C0086437
Finding
Lack of stability of a joint.
Generalized hypotonia
MedGen UID:
346841
Concept ID:
C1858120
Finding
Generalized muscular hypotonia (abnormally low muscle tone).
Progressive macrocephaly
MedGen UID:
395368
Concept ID:
C1859896
Finding
The progressive development of an abnormally large skull.
Downslanted palpebral fissures
MedGen UID:
98391
Concept ID:
C0423110
Finding
The palpebral fissure inclination is more than two standard deviations below the mean.
Epicanthal fold
MedGen UID:
151862
Concept ID:
C0678230
Congenital Abnormality
Epicanthus is a condition in which a fold of skin stretches from the upper to the lower eyelid, partially covering the inner canthus. Usher (1935) noted that epicanthus is a normal finding in the fetus of all races. Epicanthus also occurs in association with hereditary ptosis (110100).
Smooth philtrum
MedGen UID:
222980
Concept ID:
C1142533
Finding
Flat skin surface, with no ridge formation in the central region of the upper lip between the nasal base and upper vermilion border.
Depressed nasal bridge
MedGen UID:
373112
Concept ID:
C1836542
Finding
Posterior positioning of the nasal root in relation to the overall facial profile for age.
Broad forehead
MedGen UID:
338610
Concept ID:
C1849089
Finding
Width of the forehead or distance between the frontotemporales is more than two standard deviations above the mean (objective); or apparently increased distance between the two sides of the forehead.
Cutis marmorata
MedGen UID:
78093
Concept ID:
C0263401
Disease or Syndrome
A reticular discoloration of the skin with cyanotic (reddish-blue appearing) areas surrounding pale central areas due to dilation of capillary blood vessels and stagnation of blood within the vessels. Cutis marmorata generally occurs on the legs, arms and trunk and is often more severe in cold weather.
Hypertelorism
MedGen UID:
9373
Concept ID:
C0020534
Finding
Although hypertelorism means an excessive distance between any paired organs (e.g., the nipples), the use of the word has come to be confined to ocular hypertelorism. Hypertelorism occurs as an isolated feature and is also a feature of many syndromes, e.g., Opitz G syndrome (see 300000), Greig cephalopolysyndactyly (175700), and Noonan syndrome (163950) (summary by Cohen et al., 1995).
Microphthalmia
MedGen UID:
10033
Concept ID:
C0026010
Congenital Abnormality
Microphthalmia is an eye abnormality that arises before birth. In this condition, one or both eyeballs are abnormally small. In some affected individuals, the eyeball may appear to be completely missing; however, even in these cases some remaining eye tissue is generally present. Such severe microphthalmia should be distinguished from another condition called anophthalmia, in which no eyeball forms at all. However, the terms anophthalmia and severe microphthalmia are often used interchangeably. Microphthalmia may or may not result in significant vision loss.\n\nPeople with microphthalmia may also have a condition called coloboma. Colobomas are missing pieces of tissue in structures that form the eye. They may appear as notches or gaps in the colored part of the eye called the iris; the retina, which is the specialized light-sensitive tissue that lines the back of the eye; the blood vessel layer under the retina called the choroid; or in the optic nerves, which carry information from the eyes to the brain. Colobomas may be present in one or both eyes and, depending on their size and location, can affect a person's vision.\n\nPeople with microphthalmia may also have other eye abnormalities, including clouding of the lens of the eye (cataract) and a narrowed opening of the eye (narrowed palpebral fissure). Additionally, affected individuals may have an abnormality called microcornea, in which the clear front covering of the eye (cornea) is small and abnormally curved.\n\nBetween one-third and one-half of affected individuals have microphthalmia as part of a syndrome that affects other organs and tissues in the body. These forms of the condition are described as syndromic. When microphthalmia occurs by itself, it is described as nonsyndromic or isolated.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVMegalencephaly-capillary malformation-polymicrogyria syndrome
Follow this link to review classifications for Megalencephaly-capillary malformation-polymicrogyria syndrome in Orphanet.

Professional guidelines

PubMed

Park HJ, Shin CH, Yoo WJ, Cho TJ, Kim MJ, Seong MW, Park SS, Lee JH, Sim NS, Ko JM
Orphanet J Rare Dis 2020 Aug 10;15(1):205. doi: 10.1186/s13023-020-01480-y. PMID: 32778138Free PMC Article

Recent clinical studies

Etiology

Di Rocco F, Licci ML, Garde A, Mottolese C, Thauvin-Robinet C, Chevarin M, Guibaud L, Vabres P, Kuentz P, Faivre L
Eur J Med Genet 2023 Feb;66(2):104678. Epub 2022 Dec 9 doi: 10.1016/j.ejmg.2022.104678. PMID: 36503153
Park HJ, Shin CH, Yoo WJ, Cho TJ, Kim MJ, Seong MW, Park SS, Lee JH, Sim NS, Ko JM
Orphanet J Rare Dis 2020 Aug 10;15(1):205. doi: 10.1186/s13023-020-01480-y. PMID: 32778138Free PMC Article

Diagnosis

St John LJ, Rao N
BMJ Case Rep 2021 Dec 30;14(12) doi: 10.1136/bcr-2021-247034. PMID: 34969807Free PMC Article
Park HJ, Shin CH, Yoo WJ, Cho TJ, Kim MJ, Seong MW, Park SS, Lee JH, Sim NS, Ko JM
Orphanet J Rare Dis 2020 Aug 10;15(1):205. doi: 10.1186/s13023-020-01480-y. PMID: 32778138Free PMC Article
McCuaig CC
Curr Opin Pediatr 2017 Aug;29(4):448-454. doi: 10.1097/MOP.0000000000000518. PMID: 28654575
Mirzaa GM, Conway RL, Gripp KW, Lerman-Sagie T, Siegel DH, deVries LS, Lev D, Kramer N, Hopkins E, Graham JM Jr, Dobyns WB
Am J Med Genet A 2012 Feb;158A(2):269-91. Epub 2012 Jan 6 doi: 10.1002/ajmg.a.34402. PMID: 22228622

Clinical prediction guides

Di Rocco F, Licci ML, Garde A, Mottolese C, Thauvin-Robinet C, Chevarin M, Guibaud L, Vabres P, Kuentz P, Faivre L
Eur J Med Genet 2023 Feb;66(2):104678. Epub 2022 Dec 9 doi: 10.1016/j.ejmg.2022.104678. PMID: 36503153

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