13q deletion syndrome

13q deletion syndrome

13q deletion syndrome

13q Deletion Syndrome is a rare genetic disease caused by the deletion of some or all of the large arm of human chromosome 13. Depending upon the size and location of the deletion on chromosome 13, the physical and mental manifestations will vary. It has the potential to cause intellectual disability and congenital malformations that affect a variety of organ systems. Because of the rarity of the disease, in addition to the variations in the disease, the specific genes that cause this disease are unknown

Chromosome 13 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 13 spans about 114 million base pairs (the building material of DNA) and represents between 3.5 and 4% of the total DNA in cells.  chromosome 13 info

13q deletion syndrome
Chromosone 13

Signs and symptoms

13q deletion syndrome gives a characteristic appearance to affected individuals, potentially including

  • microphthalmia (small eyes)
  • hypertelorism (wide-set eyes)
  • thin forehead
  • high palate
  • underdeveloped midface
  • small mouth,
  • small nose
  • broad and flat nasal bridge
  • short neck
  • low hairline
  • irregular or wrongly positioned teeth
  • low-set ears
  • short stature
  • microcephaly (small head)
  • earlobes turned inwards

Defects of the endocrine system, digestive system and genitourinary system are also common. These include underdevelopment of the pancreas, adrenal glands, gallbladder and thyroid.

A variety of brain abnormalities are also associated with 13q deletion syndrome which can include epilepsy and deafness. The eyes can be severely damaged and affected individuals may be blind. They may also have cataracts.

Other skeletal malformations are found with 13q deletion syndrome, including clubfoot and malformations of the vertebrae and/or thumbs.

Causes

Although one can inherit 13q deletion syndrome, the most common way to obtain the disease is through genetic mutations. All human chromosomes have 2 arms, the p (short) arm and the q (long) arm. They are separated from each other only by a primary constriction, the centromere, the point at which the chromosome is attached to the spindle during cell division.

When portions of the long arm of chromosome 13 are altered during gametogenesis, 13q deletion syndrome results. Because the 13th chromosome holds between 300 and 400 genes, and a deletion of any part of this chromosome or mutation can lead to a large variety of malfunctions within the system.

The physical role of the centromere is to act as the site of assembly of the kinetochores – a highly complex multiprotein structure that is responsible for the actual events of chromosome segregation. centromere info

Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes.  gametogenesis info

centromere
Centromere

 

Gametogenesis 
Gametogenesis

Diagnosis

13q deletion syndrome can only be definitively diagnosed by genetic analysis, which can be done prenatally or after birth. Family and medical history is important when diagnosing a child with 13q deletion syndrome. Chromosome testing of both parents can provide more information on whether or not the deletion was inherited

Treatment

Although there is no cure for 13q deletion syndrome, symptoms can be managed, usually with the involvement of a neurologist, rehabilitation physician, occupational therapist, physiotherapist, psychotherapist, nutritionist, special education professional, and/or speech therapist.

No treatment for 13q deletion syndrome will ever be identical due to the variations in the disease which is why the use of personalized teams with members from different medical fields is vital to the patient.

Even if a child is responding well to his medical treatment, it is important to utilize special educators, speech and occupational therapists and physiotherapists to help the child develop skills that will aid in his/her life in and out of the classroom.

Afterword

Unfortunately, affected individuals do have a somewhat shortened lifespan. The maximum described lifespan is 67 years. It is not uncommon for adults with 13q deletion syndrome to need support services to maintain their activities of daily living, including adult day care services or housing services.

Many children with a large deletion will have respiratory issues and they catch any infections very quickly and recovery takes longer. Sometimes pneumonia can attack and it could be severe enough that the child’s body can not fight it and child may pass away.

But properly protecting the child from getting infection (from school, from home, from crowded places) possibly could prevent infection.


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