| Phenotype (plain) | Suggested HPO term(s) | Typical timing/onset | Notes on frequency | Key evidence (include abstract quotes if present) | Key references/URL |
|---|---|---|---|---|---|
| Hypogonadotropic hypogonadism | HP:0000044 Hypogonadotropic hypogonadism | Congenital; usually recognized in infancy (mini-puberty) or adolescence | Core/defining feature; effectively universal in KS by definition | KS is defined as congenital HH with olfactory dysfunction; Laitinen: KS is “comprised of congenital hypogonadotropic hypogonadism (HH) and anosmia” (pqac-00000003, pqac-00000017) | Laitinen 2011 https://doi.org/10.1186/1750-1172-6-41; Żak 2024 review (pqac-00000007) |
| Delayed or absent puberty | HP:0000823 Delayed puberty; HP:0008197 Absent puberty | Adolescence | Very common/core presentation; often the reason for diagnosis | Żak 2024 notes absent or incomplete pubertal development in adolescence; Meczekalski 2013 describes “absence of spontaneous puberty” and arrested sexual maturation in female KS (pqac-00000007, pqac-00000004) | Meczekalski 2013 https://doi.org/10.3109/09513590.2012.752459; Żak 2024 review (pqac-00000007) |
| Anosmia / hyposmia | HP:0000458 Anosmia; HP:0004409 Hyposmia | Congenital, though often recognized in childhood/adolescence | Core/defining feature; required to distinguish KS from normosmic CHH | Sayed 2023 lists anosmia as a clinical “red flag”; Laitinen used UPSIT with anosmia defined as “<5th percentile for age”; Żak 2024 and Liu 2022 define KS by HH plus hyposmia/anosmia (pqac-00000003, pqac-00000014, pqac-00000016) | Sayed 2023 https://doi.org/10.1038/s41431-022-01261-0; Laitinen 2011 https://doi.org/10.1186/1750-1172-6-41 |
| Infertility / subfertility | HP:0000789 Infertility | Usually recognized in adulthood | Very common if untreated; treatment-responsive in many patients | Sayed 2023 states CHH/KS causes “reduced potential for fertility” and that fertility can be restored in “approximately 75% of men and women”; Żak 2024 notes infertility is common in adults with KS (pqac-00000014, pqac-00000007) | Sayed 2023 https://doi.org/10.1038/s41431-022-01261-0; Żak 2024 review (pqac-00000007) |
| Cryptorchidism | HP:0000028 Cryptorchidism | Neonatal/infancy in males | Important early clue in boys; qualitative frequency high enough to be a classic red flag; one Chinese IHH cohort reported 35% overall among male patients, not KS-specific (pqac-00000000) | Sayed 2023 includes cryptorchidism among KS/CHH “red flag” features; Żak 2024 lists neonatal male presentation with cryptorchidism; Liu 2022 highlights neonatal male signs including cryptorchidism (pqac-00000014, pqac-00000007, pqac-00000016) | Sayed 2023 https://doi.org/10.1038/s41431-022-01261-0; Żak 2024 review (pqac-00000007) |
| Micropenis | HP:0000054 Micropenis | Neonatal/infancy in males | Important early clue; qualitative classic sign of congenital GnRH deficiency | Sayed 2023 lists micropenis as a clinical red flag; Liu 2022 notes neonatal male signs such as “cryptorchidism and micropenis (stretched penile length <2.5 cm)”; Żak 2024 also notes micropenis in neonatal males (pqac-00000014, pqac-00000016, pqac-00000007) | Sayed 2023 https://doi.org/10.1038/s41431-022-01261-0; Liu 2022 https://doi.org/10.1007/s43032-021-00638-8 |
| Renal agenesis (often unilateral) | HP:0000122 Renal agenesis; HP:0010957 Unilateral renal agenesis | Congenital | Non-reproductive associated anomaly; frequency variable and gene-dependent | Żak 2024 lists “Unilateral renal agenesis”; Laitinen 2011 and Liu 2022 include renal agenesis among associated non-reproductive features; Sayed 2023 lists renal agenesis among red flags (pqac-00000015, pqac-00000009, pqac-00000014, pqac-00000016) | Laitinen 2011 https://doi.org/10.1186/1750-1172-6-41; Sayed 2023 https://doi.org/10.1038/s41431-022-01261-0 |
| Cleft lip and/or palate | HP:0000202 Cleft palate; HP:0000204 Cleft upper lip | Congenital | Non-reproductive associated anomaly; variable | Laitinen 2011 lists “cleft lip/palate”; Żak 2024 lists “cleft palate and lip”; Sayed 2023 includes midline defects such as cleft palate (pqac-00000009, pqac-00000015, pqac-00000014) | Laitinen 2011 https://doi.org/10.1186/1750-1172-6-41; Żak 2024 review (pqac-00000015) |
| Dental agenesis / hypodontia | HP:0009804 Tooth agenesis; HP:0000674 Hypodontia | Congenital; often recognized in childhood/adolescence | Variable but well-established associated feature | Laitinen 2011 lists “dental agenesis”; Żak 2024 lists “hypodontia”; Liu 2022 includes “dental agenesis” in the broad phenotype; FGFR1-associated dental anomalies are repeatedly cited (pqac-00000009, pqac-00000015, pqac-00000016) | Laitinen 2011 https://doi.org/10.1186/1750-1172-6-41; Liu 2022 https://doi.org/10.1007/s43032-021-00638-8 |
| Synkinesis / mirror movements | HP:0003128 Mirror movements | Childhood onward; often longstanding | Classic associated neurologic sign; variable, gene-enriched | Laitinen 2011 lists “mirror movements”; Sayed 2023 lists “synkinesis (mirror movements)” as a red flag; Liu 2022 includes “mirror movements” in the phenotypic spectrum (pqac-00000009, pqac-00000014, pqac-00000016) | Laitinen 2011 https://doi.org/10.1186/1750-1172-6-41; Sayed 2023 https://doi.org/10.1038/s41431-022-01261-0 |
| Hearing impairment | HP:0000365 Hearing impairment | Congenital or early-life; may be recognized later | Variable associated feature | Laitinen 2011 lists “hearing impairment”; Żak 2024 notes “central hearing impairment”; Liu 2022 lists “hearing loss” among broader phenotypes; He 2023 lists hearing loss among non-reproductive features (pqac-00000009, pqac-00000015, pqac-00000016, pqac-00000005) | Laitinen 2011 https://doi.org/10.1186/1750-1172-6-41; He 2023 https://doi.org/10.2147/ijgm.s430904 |
| Eye movement abnormalities / ataxia | HP:0000640 Oculomotor apraxia/abnormality of eye movement; HP:0001251 Ataxia | Childhood onward | Variable neurologic manifestations; not universal | Liu 2022 lists “eye movement abnormalities”; Żak 2024 lists “ataxia”; Laitinen 2011 includes associated anomalies and later reviews emphasize cerebellar/oculomotor involvement in some patients (pqac-00000016, pqac-00000015, pqac-00000009) | Liu 2022 https://doi.org/10.1007/s43032-021-00638-8; Żak 2024 review (pqac-00000015) |
| Psychological impact / reduced quality of life | HP:0012735 Emotional lability or use broader term: HP:0000716 Depression; HP:0000739 Anxiety | Often emerges in adolescence/adulthood | Qualitatively important; related to delayed puberty, infertility, body image, chronic disease burden | Żak 2024 notes “significant psychological morbidity” and elevated BDI/BAI/ASEX scores in cited literature; the review emphasizes psychosocial burden and the need for psychological support (pqac-00000001, pqac-00000006) | Żak 2024 review (pqac-00000001, pqac-00000006) |
| Low gonadotropins and inhibin B | HP:0011968 Decreased circulating luteinizing hormone level; HP:0011969 Decreased circulating follicle stimulating hormone level; HP:0034343 Decreased circulating inhibin B level | Detectable in infancy (mini-puberty) and at diagnostic evaluation later | Characteristic laboratory abnormality; central to diagnosis | Żak 2024: “Patients of both sexes with KS exhibit very low plasma levels of gonadotropins, including FSH, LH and inhibin B”; He 2023 describes “low or inappropriately normal serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH)” with low sex steroids (pqac-00000001, pqac-00000005, pqac-00000015) | Żak 2024 review (pqac-00000001); He 2023 https://doi.org/10.2147/ijgm.s430904 |
| Primary amenorrhea / absent breast development in affected females | HP:0000786 Primary amenorrhea; HP:0000066 Hypogonadism; HP:0000824 Delayed menarche | Adolescence | Common female presentation but female cases are under-recognized | Żak 2024 notes underdeveloped breasts and primary amenorrhea in girls; Meczekalski 2013 discusses incomplete secondary sexual characteristics in women with KS (pqac-00000007, pqac-00000004) | Meczekalski 2013 https://doi.org/10.3109/09513590.2012.752459; Żak 2024 review (pqac-00000007) |
| Osteopenia / osteoporosis / fracture risk | HP:0000939 Osteoporosis; HP:0002758 Osteopenia | Usually chronic, emerging in adolescence/adulthood if untreated | Secondary complication of untreated hypogonadism; clinically important | Meczekalski 2013 states “Untreated KS patients have increased risk of osteoporosis” and “higher incidence of osteopenia or osteoporosis and have a greater fracture risk”; Żak 2024 notes risk of early osteoporotic fractures (pqac-00000004, pqac-00000000) | Meczekalski 2013 https://doi.org/10.3109/09513590.2012.752459; Żak 2024 review (pqac-00000000) |


*Table: This table summarizes the core reproductive, olfactory, neurologic, congenital, psychological, and laboratory phenotypes reported in Kallmann syndrome, with suggested HPO mappings and evidence-linked notes. It is useful for structured disease knowledge-base curation and phenotype annotation.*