Chromosome 14q Deletion Syndrome (2023)

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

• 14q Deletion Syndrome
• 14q Monosomy Syndrome
• Partial Monosomy 14q Syndrome

What is Chromosome 14q Deletion Syndrome? (Definition/Background Information)

• Chromosome 14q Deletion Syndrome is a rare chromosomal disorder that develops when there is missing genetic material on chromosome 14 (on long arm q) leading to a set of associated signs and symptoms. These may be mild or severe, depending on several factors such as the amount of genetic material lost, the number of genes affected, and the function of the affected genes
• The condition affects newborn children (congenital manifestation). It can result in growth and development delays, poor muscle tone, birth defects, and speech and language issues. Chromosome 14qDeletion Syndrome may present complications such as malnutrition due to feeding difficulties, delayed achievement of milestones, and reduced quality of life
• This chromosomal anomaly may develop from sporadic mutations (vast majority of cases), or it may be inherited from one’s parents (very rarely). 14qDeletion Syndrome may be diagnosed through specialized genetic testing. In some children, the condition may be mild and hence can also remain undiagnosed
• Following a diagnosis, the condition may be managed based on the presenting symptoms and extent of involvement of the body systems. The treatment of Chromosome 14qDeletion Syndrome may involve physician experts from several specialties, and can include the use of hearing aids, seizure control, speech and language therapy, physiotherapy, and surgery for correction of heart defects
• The prognosis is primarily dependent on the severity of the disorder, and it varies from one child to another. Many children with Chromosome 14q Deletion Syndrome are able to cope well through adequate treatment and supportive care. Some of the abnormalities are also known to improve with time

Who gets Chromosome 14q Deletion Syndrome? (Age and Sex Distribution)

• Chromosome 14q DeletionSyndrome is a rare congenital disorder. The presentation of symptoms may occur at or following the birth of the child
• In many cases, individuals with mild signs and symptoms may be undiagnosed in their lifetime. Hence, a true incidence of the disorder may be difficult to estimate
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Chromosome 14q Deletion Syndrome? (Predisposing Factors)

In a vast majority of individuals, there are no identified risk factors for Chromosome 14qDeletion Syndrome.

• A positive family history may be an important risk factor, since 14q DeletionSyndrome can be inherited
• Currently, no environmental and lifestyle (including dietary) factors have been implicated
• The syndrome is not caused by what the expectant mother does or does not do, either prior to or during pregnancy

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 Chromosome 14q Deletion Syndrome? (Etiology)

Chromosome 14q Deletion Syndrome can be caused in the following manner:

• A de-novo deletion of genetic material in the long arm (q) of chromosome 14 (majority of cases)
• Heritable changes passed from a parent with Chromosome 14q Deletion in which a subsequent chromosomal re-arrangement has led to a balanced translocation (rare)
• If the chromosomal re-arrangement does not result in a net gain or loss of genetic material, it is known as a “balanced translocation”
• Those with balanced translocation of 14q can have abnormalities in the development of egg or sperm, causing the disorder in their offspring
• There are two chromosomes numbered 14. Children with Chromosome 14q Deletions typically will have one (chromosome 14) in normal condition, while the other is abnormal. The abnormality is characterized by a loss of chromosomal material

It is important to note that a child’s development and future is not only influenced by the chromosome material duplicated/deleted and genes involved, but also by other factors such as one’s environment, involvement of other genes, and unique personality.

Additional (general) information on chromosomes, which is helpful in understanding the disorder:

Chromosomes are microscopic thread-like protein structures present in each cell nucleus that carry genetic information in the form of DNA (deoxyribonucleic acid). DNAs are nucleic acids that encodes the genetic information of any organisms; a basic unit of the DNA is termed a gene with a specific set of instructions and a defined function. Each chromosome is “X” shaped with a center, called the centromere, and two short arms (termed p arms) and two long arms (termed q arms).

Humans have 46 chromosomes in the cell nucleus, in 23 pairs, of which one pair is named the sex chromosome. In males, it is designated XY, for chromosome X and chromosome Y; while, in females, it is designated XX, for a pair of chromosome X. The other 22 pairs of chromosomes are numbered chromosome 1 through 22, approximately according to size (with chromosome 1 being the largest; chromosome 21 being the smallest) and are referred to as autosomes or somatic chromosomes. During conception, the embryo inherits one copy of each chromosome from each parent (i.e., mother and father). Any alteration in the chromosome numbers or structure, such as via addition or deletion of chromosomal material, can result in mild to severe genetic abnormalities that may manifest as birth defects, growth delays, and intellectual disabilities.

A chromosome deletion disorder indicates that a certain portion of the chromosomal material is missing, which may be detected through molecular genetic testing. Depending on the nature and amount of material deleted, the manifestation of a set of signs and symptoms are noted.

What are the Signs and Symptoms of Chromosome 14q Deletion Syndrome?

The signs and symptoms of Chromosome 14q Deletion Syndrome may be significantly different from one individual to another. The degree of signs and symptoms are often related to the amount of chromosome material deleted and the number of genes affected. As a general rule, a small loss of chromosome material generally results in milder signs and symptoms. Conversely, larger deletion of the chromosome material generally results in severe signs and symptoms. It is important to note that exceptions may also occur, where individuals with small amount of chromosomal loss, may have disproportionately severe presentations.

The commonly noted signs and symptoms of 14q Deletion Syndrome include:

• Developmental delays; delays in reaching milestones
• Large-sized head (due to large brain size), including prominent forehead
• Poor muscle tone (hypotonia) causing motor delays that can be mild or severe, particularly during infancy. This can cause the following:
  • Feeding problems (sucking and swallowing) leading to small and underweight children
  • Difficulty in holding small items such as a cup or spoon
  • Drawing and writing difficulties
  • Difficulty in climbing stairs and difficulty in sitting without support
  • Standing and walking difficulties
  • Help needed for wearing clothes and undressing
• Vision impairment
• Epileptic seizures are noted in children
• Presence of hand or foot abnormalities
• Intellectual disabilities
• Speech and learning disabilities (slow learning)
• Psychomotor impairment (i.e., slowing down of physical reactions, movements, and speech)

How is Chromosome 14q Deletion Syndrome Diagnosed?

Children can have varying signs and symptoms. Some children with mild signs and symptoms may go undiagnosed in their lifetimes. Given the rarity of the condition, the healthcare provider should have a high index of suspicion to consider Chromosome 14q DeletionSyndrome in the differential diagnosis. Often, specialized tests are necessary to confirm the disorder.

14q DeletionSyndrome is diagnosed on the basis of the following information:

• Complete physical examination and thorough medical history evaluation, including family medical history
• Assessment of the presenting signs and symptoms, including evaluation of body systems such as vision, hearing, muscles, heart, kidneys, central nervous system, genitalia, and immune system
• Hearing and vision assessment through various tests
• Laboratory tests, as needed, such as electrolyte levels, serum calcium levels, thyroid function test, kidney function test, urine tests, sex hormone studies, etc.
• Radiological studies of the affected regions, as needed
• Neurological examination that involves the central nervous system (brain and spinal cord)
• Behavioral studies
• Prenatal studies including abdominal ultrasonography
• Specialized genetic testing techniques are often required to confirm the diagnosis. This may include:
  • Fluorescence in situ hybridization (FISH) testing
  • Array comparative genomic hybridization (array-CGH)
  • DNA sequencing

Often, karyotyping of the chromosome is not adequate to diagnose the condition, since individuals with this condition can have normal karyotype chromosomal studies.

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 Chromosome 14q Deletion Syndrome?

The complications of Chromosome 14q Deletion Syndrome may include:

• Severe emotional stress for parents and caregivers
• Pregnancy complications
• Delayed milestone achievement that may affect when a child rolls, sit, crawl, or walk
• Seizures causing fall injuries
• Poor growth due to malnutrition caused by weak suckling
• Severe intellectual deficiency
• Inappropriate or violent behavior
• Physical abnormalities that can cause difficulties in day-to-day living

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

How is Chromosome 14q Deletion Syndrome Treated?

There is no cure for Chromosome 14q DeletionSyndrome since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complication that develops. It also depends on the severity of the signs and symptoms and the body systems affected. Individuals with mild signs and symptoms may require periodic monitoring without significant medical intervention. Often, a multidisciplinary team of specialists including pediatricians, ophthalmologists, otolaryngologists, neurologists, internists, cardiologists, endocrinologists, surgeons, and other healthcare professionals are involved in managing the condition.

The treatment measures for 14q DeletionSyndrome may involve:

• Employing learning strategies via music therapy, visual and tactile books, touch screen computers, etc.
• Speech and language therapy; the use of sign language may be beneficial
• Physiotherapy for weakened muscles, including incorporating daily exercise regimen
• Development of motor skills via daily exercises, swimming, and other adapted activities; use of specially-designed toys and daily-used items (such as spoons and cups)
• For feeding difficulties, use of feeding tubes (temporary), medications, feed thickeners, including special diets and nutritional supplements
• Surgical correction of physical defects, as assessed by a healthcare expert
• Use of suitable glasses and surgical rectification of vision defects
• Surgical correction (orchiopexy) of undescended testicles and other genital defects
• Psychotherapy, behavior modification, and establishing discipline techniques, as necessary
• Occupational therapy

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

How can Chromosome 14q Deletion Syndrome be Prevented?

Chromosome 14q Deletion Syndrome may not be preventable since many of these genetic disorders are diagnosed at or following the birth of the child. A majority of cases are sporadic occurrences, which means there is no family history of the condition.

In some rare cases, the condition may be familial, meaning they occur within families. In expecting parents with a familial history:

• 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

It is important to note that the chances of both the parents with normal chromosomes having another child with 14q Deletion Syndrome is highly unlikely. This may be confirmed via specialized prenatal testing and preimplantation genetic diagnosis (PGD), if needed. Prenatal tests may includechorionic villus sampling (CVS) and amniocentesis.

What is the Prognosis of Chromosome 14q Deletion Syndrome? (Outcomes/Resolutions)

The prognosis of Chromosome 14q Deletion Syndromeis dependent upon the severity of the signs and symptoms and associated complications, if any.

• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• In some cases, lifelong medical support and care is necessary

Additional and Relevant Useful Information for Chromosome 14q Deletion Syndrome:

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

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

Helpful Peer-Reviewed Medical Articles:

Telford, N., Thomson, D. A., Griffiths, M. J., Ilett, S., & Watt, J. L. (1990). Terminal deletion (14)(q32. 3): a new case. Journal of medical genetics, 27(4), 261-263.

Bennett, C. P., Betts, D. R., & Seller, M. J. (1991). Deletion 14q (q22q23) associated with anophthalmia, absent pituitary, and other abnormalities. Journal of medical genetics, 28(4), 280-281.

Elliott, J., Maltby, E. L., & Reynolds, B. (1993). A case of deletion 14 (q22. 1--> q22. 3) associated with anophthalmia and pituitary abnormalities. Journal of medical genetics, 30(3), 251-252.

Meschede, D., Exeler, R., Wittwer, B., & Horst, J. (1998). Submicroscopic deletion in 14q32. 3 through a de novo tandem translocation between 14q and 21p. American Journal of Medical Genetics Part A, 80(5), 443-447.

Chen, C. P., Chern, S. R., Lee, C. C., Chen, W. L., Chen, M. H., & Chang, K. M. (1998). De novo unbalanced translocation resulting in monosomy for proximal 14q and distal 4p in a fetus with intrauterine growth retardation, Wolf-Hirschhorn syndrome, hypertrophic cardiomyopathy, and partial hemihypoplasia. Journal of medical genetics, 35(12), 1050-1053.

De Pater, J. M., Nikkels, P. G. J., Poot, M., Eleveld, M. J., Stigter, R. H., van der Sijs-Bos, C. J. M., ... & Engelen, J. J. M. (2005). Striking facial dysmorphisms and restricted thymic development in a fetus with a 6-megabase deletion of chromosome 14q. Pediatric and Developmental Pathology, 8(4), 497-503.

Bregant, L., Gersak, K., & Veble, A. (2005). Distal trisomy 10q/partial monosomy 14q: an unusual clinical picture. Genetic counseling (Geneva, Switzerland), 16(1), 59-63.

Chen, C. P., Chang, Y. L., Chern, S. R., Wu, P. S., Su, J. W., Chen, W. L., ... & Wang, W. (2013). Prenatal diagnosis of partial trisomy 3q (3q27. 3→ qter) and partial monosomy 14q (14q31. 3→ qter) of paternal origin associated with fetal hypotonia, arthrogryposis, scoliosis and hyperextensible joints. Gene, 516(1), 132-137.