This is a genetic condition presents intellectual disorder along with the additional physical and clinical features. Individuals affected with this syndrome exhibit a wide range of symptoms and the severity varies in each case. Kleefstra syndrome develops as the result of the damage or deletion in certain genes. The exact prevalence of this rare disorder is not known as most of the times the features of this condition has been associated with other disorders.
Causes
Kleefstra syndrome develops from the deletion of the EHMT1 gene or from the mutation that affects its function. This gene is important for the production of an enzyme known as euchromatic histone methyltransferase 1 that modifies certain proteins called histones that are necessary for the normal development. Most individuals with this syndrome are missing the sequence on one copy of chromosome 9 in each cell. The deletion of the EHMT1 gene from one copy of the chromosome 9 in each cell causes the features that are characteristic of this condition. The deletion of other genes in the same region of the chromosome can cause the additional health condition. Most cases of this syndrome develop as the result of a new mutation called ‘de novo’ meaning they are not inherited from the parents although rarely individuals with this syndrome can pass the disorder to their children.
Symptoms
Most of the affected children exhibit severely delayed or absent speech, learning disability, intellectual disability and the delayed physical milestones as the result of the low muscle tone. The distinctive facial features include a small sized head, short skull (brachycephaly), widely spaced eyes, nostrils that open to the front (anteverted nares), rolled out lips, large tongue and a protruding jaw. Additional common features include structural brain abnormalities, heart conditions, features of autism, sleep difficulties, severe respiratory infections, minor genitourinary abnormalities and behavioral difficulties. Less commonly, the affected children may present dental abnormalities, kidney anomalies, hearing impairment and connective tissue disorder.
Diagnosis
This syndrome can be diagnosed based on the identification of the features that are characteristic of this condition, clinical evaluation and with various tests. The genetic tests can usually confirm the disorder among the symptomatic individuals and the family members at risk. The molecular genetic tests can prevent the unnecessary need for various testing and procedures. Generally, the genetic testing is considered when the affected individuals exhibit the distinctive facial features and additional abnormalities such as intellectual disability, frequent respiratory infections, brain malformations, problems with the urogenital or the heart and hypotonia.
Treatment
There is no cure for this syndrome and the treatment is focused on providing supportive care. The affected children can benefit from the early intervention of various therapies. As most of the cases present low muscle tone, physical therapy can provide support by building their gross motor skills. The occupational therapy, speech therapy can also greatly benefit these children which can also assist with feeding issues. The affected families may also benefit from the genetic counseling.
References
http://www.kleefstrasyndrome.org/what-is-kleefstra-syndrome
https://ghr.nlm.nih.gov/condition/kleefstra-syndrome