A genetic disorder that negatively affects the production of hormones that support sexual development and the sense of smell is called Kallmann syndrome (KS). It often occurs due to certain genetic mutations that happen during fetal development. While some children inherit the abnormal genes, others develop them spontaneously.
In other words, KS is a condition that causes delayed puberty and may cause anosmia. While it occurs due to certain gene mutations that occur sporadically during pregnancy, some people may get the abnormal genes from their biological parents. Some healthcare professionals think that Kallmann syndrome is a type of hypogonadotropic hypogonadism. Generally, hypogonadism is a condition in which the ovaries or testicles do not produce enough sex hormones.
What Are The Symptoms of Kallmann Syndrome?
People who develop this syndrome usually experience the following symptoms that may appear during childhood or adulthood. Check some examples below:
- Lack of breast development (girls)
- Small penile and testicles (boys)
- Significantly delayed periods (girls)
- Cleft palate
- Balance problems
- Infertility that can affect both boys and girls
- Extreme tiredness (fatigue)
- Nystagmus (abnormal eye movement)
- Dental abnormalities (including missing teeth or unusually small teeth)
- Irregular menstrual periods (women)
- Low sex drive
- Unusual weight gain
- Renal agenesis (missing kidney)
- Scoliosis
- Mood swings
If you or your child has any of the symptoms listed above, immediately contact your healthcare professional. Leaving this condition unmanaged may lead to serious complications.
Causes
This genetic condition is caused by a genetic mutation that negatively affects the process that drives puberty. Normally, it starts when the child’s hypothalamus produces gonadotropin-releasing hormone (GnRH). However, in people with KS, the child’s hypothalamus does not produce enough of this hormone, and puberty does not start. Furthermore, GnRH also supports sexual maturity, sex drive, and fertility. It also tells the pituitary gland to produce two more hormones called follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
Some of these genetic changes may also affect the way a child’s brain processes smells. While olfactory nerve cells detect and send information about smells to the olfactory bulb, in children with KS, these signals do not reach the brain. As a result, it may lead to anosmia (loss of sense of smell) and normosmic idiopathic hypogonadotropic hypogonadism (nIHH).
According to some research, there are more than 25 genetic mutations that can cause KS and other forms of hypogonadotropic hypogonadism. Check some of them below:
- IL17RD
- PROK2
- SOX10
- TACR3
- FGFR1
- CHD7
- KAL1 (ANOS1)
- GNRHR
In addition, healthcare professionals have identified several ways a person can inherit these abnormal genes. For example:
- Autosomal recessive inheritance – In such cases, both biological parents carry the abnormal gene that causes Kallmann syndrome.
- Autosomal dominant inheritance – In this case, the children receive the abnormal gene only from one parent who carries it.
- X-linked inheritance – This term means that both biological parents pass the mutated gene to their children in genes on the X chromosome.
What Are The Long-Term Effects of Kallmann Syndrome?
People who are diagnosed with KS may experience some complications, especially when the condition is poorly managed. Check some examples below:
- Infertility – When the brain no longer produces GnRH, normal sexual maturation is affected. Without treatment, it may lead to infertility in both men and women.
- Hypogonadism – A lack of sex hormones for long periods may cause erectile dysfunction (ED), low libido, irregular periods, and reduced muscle mass.
- Osteoporosis (bone loss), which significantly increases the risk of bone fractures
- Anosmia or hyposmia
- Renal and skeletal abnormalities
- Bimanual synkinesis
- Hearing impairment
- Emotional stress
- Low self-esteem
- Depression
- Anxiety
- Reduced quality of life
This document does not contain all possible complications of KS. However, doctors may recommend some ways to reduce the risk or even prevent them. Additionally, there is no way to prevent this condition because it occurs due to a genetic mutation that is passed from biological parents or develops randomly.
Diagnosis
Like the diagnosis of other health conditions, the diagnosis of KS starts with a physical examination in which doctors will check for abnormalities linked to the disease. After that, doctors may also ask some questions about your family history and symptoms to gather more information about your health problem. In any case, to confirm or rule out Kallmann syndrome, they will perform the following tests. These include:
- Tests to check your sense of smell
- Genetic tests
- Blood tests
Treatment
One of the most common treatments is hormone replacement therapy, but doctors may also recommend other options to manage this condition. These include:
- Estrogen and progesterone pills or skin patches (women)
- Testosterone injections, skin patches, or skin gels (men)
- GnRH injections to bring on ovulation or menstrual periods
- HCG injections (human chorionic gonadotropin) – These injections are used to boost testosterone levels and sperm in males. In rare cases, they may also help increase the chance of pregnancy in women.
Frequently Asked Questions
What can I expect if my child has Kallmann syndrome?
If you have a child with KS, he/she will need long-term hormone replacement therapy to make sure they develop properly.
What is the life expectancy with Kallmann syndrome?
In general, this condition does not affect your lifespan. However, the life expectancy can be affected if you or your child develops complications (such as osteoporosis, heart disease, and others). For more details, discuss it with your doctor.
What are the primary symptoms of Kallmann syndrome?
Usually, the primary symptoms of people with KS are anosmia (loss of sense of smell) and delayed puberty.
Can people with Kallmann syndrome have children?
Yes. Although infertility is common in people with Kallmann syndrome, many women can achieve pregnancy, especially with appropriate fertility treatments. Hormone therapy with gonadotropins or pulsatile GnRH can stimulate ovulation in women and sperm production in men.
At what age is Kallmann syndrome usually diagnosed?
Kallmann syndrome is most often diagnosed during adolescence when puberty does not begin as expected. In some cases, it may be suspected during infancy in boys with undescended testicles or a very small penis, or later in adulthood when infertility is investigated.
Is Kallmann syndrome more common in males or females?
Kallmann syndrome is diagnosed more frequently in males than females, partly because delayed puberty and genital abnormalities are often more noticeable in boys. However, females can also be affected and may experience delayed breast development, absent or delayed menstrual periods, and infertility.
Can Kallmann syndrome be cured?
No. There is currently no cure for Kallmann syndrome because it is a genetic disorder. However, hormone replacement therapy and fertility treatments can effectively manage symptoms, support normal sexual development, and improve bone health.
Does everyone with Kallmann syndrome lose their sense of smell?
No. While many people with Kallmann syndrome have anosmia (complete loss of smell) or hyposmia (reduced sense of smell), the severity varies. Some individuals have only a partial reduction in their ability to smell, while others may have a normal sense of smell, whether they have a related condition called normosmic idiopathic hypogonadotropic hypogonadism (nIHH).
Why is early treatment important for Kallmann syndrome?
Early diagnosis and treatment help promote normal puberty, improve bone density, support healthy muscle development, and reduce the risk of complications such as osteoporosis, infertility, and emotional or psychological distress. Early intervention can also improve overall quality of life.
Should family members of someone with Kallmann syndrome consider genetic counseling?
Yes. Because Kallmann syndrome can be inherited, genetic counseling may help family members understand their risk of carrying or passing on disease-causing gene variants. It can also provide useful information for family planning and determine whether genetic testing is appropriate. Ask your healthcare provider if you have any other questions.
