Velocardiofacial syndrome


Velocardiofacial syndrome

Description, Causes and Risk Factors:

A syndrome with hypernasal speech, dysmorphic facial features (long midface, cylindrical nose, downward turned corners of mouth), and cardiac abnormalities; same chromosomal abnormality as seen in DiGeorge syndrome (a microdeletion in chromosome 22q11); dominant inheritance.

Velocardiofacial syndrome is also called the 22q11.2 deletion syndrome.

Velocardiofacial syndrome is a genetic condition that is sometimes hereditary. Velocardiofacial syndrome is characterized by a combination of medical problems that vary from child to child. These medical problems include: cleft palate, or an opening in the roof of the mouth, and other differences in the palate; heart defects; problems fighting infection; low calcium levels; differences in the way the kidneys are formed or work; a characteristic facial appearance; learning problems; and speech and feeding problems.

The name velocardiofacial syndrome comes from the Latin words 'velum' meaning palate, 'cardia' meaning heart and 'facies' having to do with the face. Not all of these identifying features are found in each child who is born with velocardiofacial syndrome. The most common features are palatal differences, heart defects, problems fighting infection, low calcium levels, differences in the kidney, characteristic facial appearance and feeding problems.

Two genes - COMT (catechol methyltransferase) and TBX1 - are associated with velocardiofacial syndrome. However, not all of the genes that cause Velocardiofacial Syndrome have been identified. Most children who have been diagnosed with this syndrome are missing a small part of chromosome 22. Chromosomes are threadlike structures found in every cell of the body. Each chromosome contains hundreds of genes. A human cell normally contains 46 chromosomes (23 from each parent). The specific location or address of the missing segment in individuals with velocardiofacial syndrome is 22q11.2.

Other genes associated with this disorder may include:

    RTN4R (also known as Nogo-66 Receptor, related to axonal regeneration and plasticity as well as myelin).

  • PRODH (one of the enzymes to convert proline to glutamate).

  • ZDH8.

  • SNAP29.

Velocardiofacial syndrome affects about 1 in 4,000 newborns. Velocardiofacial syndrome may affect more individuals, however, because some people who have the 22q11.2 deletion may not be diagnosed as they have very few signs and symptoms.

Symptoms:

Despite the involvement of a very specific portion of chromosome 22, there is great variation in the symptoms of this syndrome. At least 30 different symptoms have been associated with the 22q11 deletion. Most of these symptoms are not present in all individuals who have Velocardiofacial syndrome.

Symptoms may include:

    Cleft palate, usually of the soft palate (the roof of the mouth nearest the throat which is behind the bony palate).

  • Heart problems.

  • Similar faces (elongated face, almond-shaped eyes, wide nose, small ears).

  • Eye problems.

  • Feeding problems that include food coming through the nose (nasal regurgitation) because of the palatal differences.

  • Middle-ear infections (otitis media).

  • Low calcium due to hypoparathyroidism (low levels of the parathyroid hormone that can result in seizures).

  • Immune system problems which make it difficult for the body to fight infections; differences in the way the kidneys are formed or how they work; weak muscles; differences in the spine such as curvature of the spine (scoliosis) or bony abnormalities in the neck or upper back; and tapered fingers.

Children who have Velocardiofacial syndrome also often have learning difficulties and developmental delays. About 65 percent of individuals with the velocardiofacial syndrome are found to have a non-verbal learning disability. When tested, their verbal IQ scores are greater than 10 points higher than their performance IQ scores. This combination of test scores brings down the full scale IQ scores but they won't represent the abilities of the individual accurately. As a result of this type of learning disability, students will have relative strengths in reading and rote memorization but will struggle with math and abstract reasoning. These individuals may also have communication and social interaction problems such as autism. As adults, these individuals have an increased risk for developing mental illness such as depression, anxiety and schizophrenia.

Diagnosis:

Velocardiofacial syndrome is suspected as a diagnosis based on clinical examination and the presence of the signs and symptoms of the syndrome.

Tests: A special blood test called FISH (fluorescence in situ hybridization) is then done to look for the deletion in chromosome 22q11.2. More than 95 percent of individuals who have Velocardiofacial syndrome have a deletion in chromosome 22q11.2.

Those individuals who do not have the 22q11.2 deletion by standard FISH testing may have a smaller deletion that may only be found using more sophisticated lab studies such as comparative genomic hybridization, MLPA (multiplex ligation-dependent probe amplification), additional FISH studies performed in a research laboratory or using specific gene studies to look for mutations in the genes known to be in this region. Again, these studies may only be available through a research lab.

Imaging:

    Chest radiography can reveal evidence of a heart defect.

  • Echocardiography is needed to rule out a heart defect, even in the absence of a heart murmur.

  • Renal ultrasonography is used to look for a structural anomaly.

  • Brain MRI is used if a severe delay is present. Numerous brain malformations have been observed in these patients, such as pachygyria or polymicrogyria, agenesis of the corpus callosum, myelomeningocele, and mild cerebellar hypoplasia or mega cisterna magna (the latter 2 are the most common).[14] Interestingly, young patients with velocardiofacial syndrome have significant differences in white matter microstructure and volume, and some of these defects seem to be associated with schizotypal behavior.[15]

Treatment:

Evaluation of patients with velocardiofacial syndrome usually occurs in an outpatient setting. In newborns, diagnosis may be made in the hospital. If needed, use medical therapy to treat heart failure, hypocalcemia, immune deficiency, feeding problems, and inadequate growth.

In terms of neurocognitive issues associated with velocardiofacial syndrome, during infancy and preschool years, feeding problems, cleft palate, and developmental disorders occupy most of the clinical management in these patients. During school years, management shifts to cognitive, behavioral, and learning disorders. The most common cognitive finding in these patients is functioning within the low-borderline range. Related features include significant visuospatial dysfunction, diminished math attainment, and executive dysfunction. In late adolescence and adult years, psychiatric illness such as schizophrenia or bipolar disorder become more of a concern because these may develop in 10% of adults with this condition.

Early intervention and speech therapies are started when possible at one year of age to assess and treat developmental delays.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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