Christianson syndrome is an X linked syndrome associated with intellectual disability, microcephaly, seizures, ataxia and absent speech. Presentation
Onset of symptoms is normally within the first year of life with truncal ataxia and seizures. The head is small (microcephaly). Common facial abnormalities include:
Long narrow face
Prominent nose
Prominent jaw
Large ears
Open mouth
Thick eyebrowsOther common features include:
Uncontrolled drooling
Abnormal eye movementsThe associated intellectual disability is usually in the profound range. Those affected often have a happy demeanor with frequent smiling and spontaneous laughter. Genetics
This condition is caused by mutations in the SLC9A6 gene. This gene is located on the long arm of the X chromosome (Xq26.3). The gene encodes a sodium/hydrogen exchanger located in the endosomes. Mutations in this gene cause a rise in the pH of the endosomes.How this causes the clinical features is not known presently. The inheritance of this condition is X-linked dominant. Diagnosis
The diagnosis may be suspected on clinical grounds.It is made by sequencing the SLC9A6 gene. Differential diagnosis
Angelman syndrome
Spinocerebellar ataxia type 29

Management
There is presently no curative treatment. Management is supportive. Epidemiology
The prevalence is not known but this is considered to be a rare disease. History
This condition was first described in 1999. The causative mutation was discovered in 2008. == References ==
They do this by directly decreasing the sensitivity of the alveoli of the mammary glands to the lactogenic hormone prolactin. Tall stature
Estrogens have been used to limit final height in adolescent girls with tall stature. They do this by inducing epiphyseal closure and suppressing growth hormone-induced hepatic production and by extension circulating levels of insulin-like growth factor-1 (IGF-1), a hormone that causes the body to grow and increase in size. Although ethinylestradiol and conjugated estrogens have mainly been used for this purpose, estradiol can also be employed. Breast enhancement
Estrogens are involved in breast development and estradiol may be used as a form of hormonal breast enhancement to increase the size of the breasts. Both polyestradiol phosphate monotherapy and pseudopregnancy with a combination of high-dosage intramuscular estradiol valerate and hydroxyprogesterone caproate have been assessed for this purpose in clinical studies. However, acute or temporary breast enlargement is a well-known side effect of estrogens, and increases in breast size tend to regress following discontinuation of treatment. Aside from those without prior established breast development, evidence is lacking for a sustained increases in breast size with estrogens. Schizophrenia
Estradiol has been found to be effective in the adjunctive treatment of schizophrenia in women. It has been found to significantly reduce positive, negative, and cognitive symptoms, with particular benefits on positive symptoms. Other estrogens, as well as selective estrogen receptor modulators (SERMs) like raloxifene, have been found to be effective in the adjunctive treatment of schizophrenia in women similarly.