Kallmann Syndrome in Females
In one of our earlier posts, we discussed what Kallmann syndrome is. In summary, Kallmann syndrome is a genetic condition characterized by an impaired sense of smell and delayed or incomplete puberty. Neurons that stimulate the hypothalamus are underdeveloped in Kallman syndrome. Without this neural input, the hypothalamus is unable to signal the release of certain hormones by the pituitary gland.
In normal development, the hypothalamus secrets gonadotropin-releasing hormone (GnRH) in a pulsatile or burst-like manner. GnRH then triggers the pituitary to release hormones related to male and female sexual function through stimulation of the gonads; testes and ovaries.
GnRH is not released in these bursts in utero, throughout infancy, and at puberty. The part of the hypothalamus that produces GnRH originally forms as part of the nose during the early stages of embryo development. That part migrates and eventually becomes part of the hypothalamus. This part does not develop in Kallmann syndrome explaining the impaired sense of smell, or anosmia.
Kallmann syndrome affects primarily males (about one in 8,000) but can also affect females (one in 40,000).
Kallmann Syndrome Female Symptoms
Delayed or incomplete puberty and impaired sense of smell are the key features of Kallmann syndrome. While both features are present from birth, the condition many times is not diagnosed until a work-up for delayed puberty is undertaken. A lack of sense of smell in childhood should be an early alert sign of the condition.
Below are additional signs and symptoms of this genetic disorder:
- Facial defects like cleft lip or palate
- Short finger or toes
- Development of one kidney
- Hearing loss
- Abnormal teeth development
- Color blindness and abnormal eye movements
- Mirror hand movements where movements of the hand are mirrored by movements of the other (bimanual synkinesis)
How Rare is Kallmann Syndrome in Females?
Kallmann syndrome in females is relatively rare affecting one in 40,000 females. To put this in perspective Down syndrome occurs in 1 in every 700 babies (males and females). Cystic fibrosis occurs in 1 in every 3,000 births (males and females).
Is Kallmann Syndrome Hereditary?
Kallmann syndrome is caused by more than mutations in 20 genes. Mutations in the ANOS1, CHD7, FGF8, FGFR1, PROK2, or PROKR2 genes are the most common causes. Depending on the mutation it can be inherited as either an autosomal dominant condition or autosomal recessive. Autosomal refers to non-sex chromosomes. Dominant means that only a single copy of the mutated gene (from one parent) is enough to cause a condition. Recessive means a mutated gene must be inherited from both parents to cause a condition.
Can a Woman with Kallmann Syndrome Get Pregnant?
Yes, a woman with Kallmann Syndrom can get pregnant. However, it requires hormone treatment and in some cases in vitro fertilization. This small study in three women with Kallmann syndrome showed that pregnancy is possible with hormone therapy.
Initial treatment in females (as well as males) with Kallmann syndrome is to provide hormones to initiate puberty. Then if a female with Kallmann syndrome wishes to become pregnant treatment is adjusted to trigger ovulation for fertilization and then sustain the pregnancy to full-term.
Kallmann Syndrome Female Treatment
Treatment of Kallmann syndrome in females requires the use of hormones. Puberty is triggered by the use of estrogen replacement and should be continued until a woman reaches the age of natural menopause which is typically age 52.
Patients with Kallmann syndrome are at higher risk of developing osteoporosis. Hormone treatment used for the development of puberty will minimize bone loss especially if the diagnosis of Kallmann syndrome is made as early as possible. If bone density with sex hormone replacement is not adequate several medications to treat women with osteoporosis can be used and including alendronate, risedronate, ibandronate, zoledronic acid, and denosumab. Adequate doses of vitamin D and calcium should be taken to maximize bone density.
Steps to prevent conditions related to loss of smell should also be employed. Because of a lack of smell, Kallman syndrome individuals may not be able to identify spoiled food or noxious gases from fire or toxic chemicals. Gas and smoke detectors should be installed in the homes. Labeling food and chemicals can limit the consumption of spoiled foods or mix dangerous chemicals.
Kallmann Syndrome Female Fertility Treatment
Gonadotropin-releasing hormone (GnRH) is given IV in pulses (to mimic the body’s natural release of GnRH from the hypothalamus). GnRH then triggers the pituitary gland to release LH (luteinizing hormone) and FSH (follicle-stimulating hormone). In women, FSH stimulates the development of follicles in the ovaries. An acute rise in LH then triggers the release of a follicle or ovulation and also leads to the development of the corpus luteum which sustains a pregnancy should it occur.