GTR Home > Conditions/Phenotypes > Kallmann syndrome 2

Disease characteristics

Excerpted from the GeneReview: Isolated Gonadotropin-Releasing Hormone (GnRH) Deficiency
Isolated gonadotropin-releasing hormone (GnRH) deficiency (IGD) is characterized by inappropriately low serum concentrations of the gonadotropins LH (luteinizing hormone) and FSH (follicle-stimulating hormone) in the setting of hypogonadism. IGD is associated with a normal sense of smell (normosmic IGD) in approximately 40% of affected individuals and an impaired sense of smell (Kallmann syndrome [KS]) in approximately 60%. IGD can first be apparent in infancy, adolescence, or adulthood. Infant boys with congenital (i.e., present at birth) IGD often have micropenis and cryptorchidism. Adolescents and adults with IGD have clinical evidence of hypogonadism and incomplete sexual maturation on physical examination. Adult males with IGD tend to have prepubertal testicular volume (i.e., <4 mL), absence of secondary sexual features (e.g., facial and axillary hair growth, deepening of the voice), decreased muscle mass, diminished libido, erectile dysfunction, and infertility. Adult females have little or no breast development and primary amenorrhea. Although skeletal maturation is delayed, the rate of linear growth is usually normal except for the absence of a distinct pubertal growth spurt.

Available tests

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Check Associated genes and Related conditions for additional relevant tests.

Associated genes

  • Also known as: BFGFR, CD331, CEK, FGFBR, FGFR-1, FLG, FLT-2, FLT2, HBGFR, HH2, HRTFDS, KAL2, N-SAM, OGD, bFGF-R-1, FGFR1
    Summary: fibroblast growth factor receptor 1

Clinical features

  • Primary amenorrhea
  • Short stature
  • Agenesis of corpus callosum
  • Intellectual disability
  • Osteopenia
  • Cryptorchidism
  • Hypogonadotrophic hypogonadism
  • Micropenis
  • Cleft palate
  • Cleft upper lip
  • Sensorineural hearing impairment
  • Choanal atresia
  • Anosmia
  • Iris coloboma
  • Malformation of the heart and great vessels
  • Clinodactyly
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