| Phenotype category | Description | Typical onset/course in retrieved evidence | Suggested HPO term(s) | Key supporting citations |
|---|---|---|---|---|
| Recurrent infections | Recurrent bacterial and viral infections are a core feature of STK4 deficiency/combined immunodeficiency. Reported examples include recurrent otitis, chest infections, skin abscesses, urinary infections, severe gastroenteritis, pneumonias, VZV/herpes zoster, and cryptosporidiosis. Frequency: not quantified in retrieved sources. | Usually childhood onset; can persist chronically into adolescence/adulthood. | HP:0002719 Recurrent infections; HP:0011106 Recurrent respiratory infections; HP:0002027 Recurrent skin infections | (pqac-00000001, pqac-00000004, pqac-00000005, pqac-00000007, pqac-00000008, pqac-00000012, pqac-00000013) |
| EBV viremia / EBV-associated disease | Persistent EBV viremia and EBV-associated lymphoproliferative disease are repeatedly reported; one 2024 paper notes nearly half of reported patients had EBV viremia. Frequency in the full literature is incompletely quantified in retrieved primary sources. | Often appears in childhood to adolescence; may be persistent/chronic. | HP:0031864 Epstein-Barr virus infection; HP:0012315 Viremia; HP:0002841 Recurrent viral infections | (pqac-00000004, pqac-00000008, pqac-00000014, pqac-00000016) |
| Lymphoma / lymphoproliferation | B-cell lymphoma, Hodgkin lymphoma, Burkitt lymphoma, and EBV-associated lymphoproliferation have been reported; lymphoma may occur even without detectable EBV. Frequency: not quantified in retrieved sources. | Childhood or adolescence in reported cases; severe, progressive complication. | HP:0002664 Neoplasm; HP:0100753 B-cell lymphoma; HP:0002830 Recurrent lymphoma | (pqac-00000004, pqac-00000005, pqac-00000008) |
| Warts / HPV disease | Cutaneous warts are common in case reports; HPV types 57 and 84 were documented in an early family, and EV/HPV susceptibility is part of the phenotype spectrum. One 2024 case specifically reported epidermodysplasia verruciformis due to HPV38. Frequency: not quantified in retrieved sources. | Often begins in childhood; can be chronic/persistent. | HP:0001923 Cutaneous warts; HP:0200058 Epidermodysplasia verruciformis; HP:0012372 Viral skin infection | (pqac-00000006, pqac-00000007, pqac-00000017) |
| Mucocutaneous candidiasis / oral thrush | Recurrent mucocutaneous candidiasis, oral thrush, and related fungal mucosal infections are recurrently described. Frequency: not quantified in retrieved sources. | Childhood onset; often recurrent. | HP:0002721 Chronic mucocutaneous candidiasis; HP:0000175 Oral candidiasis | (pqac-00000001, pqac-00000006, pqac-00000007, pqac-00000008) |
| Tuberculosis / mycobacterial-like infection | Pulmonary tuberculosis, granulomatous lymphadenopathy evoking mycobacterial infection, and prolonged anti-TB therapy have been reported in individual patients. Frequency: not quantified in retrieved sources. | Childhood to adolescence; may be prolonged/relapsing. | HP:0032264 Tuberculosis; HP:0002840 Increased susceptibility to mycobacterial infection; HP:0002716 Lymphadenopathy | (pqac-00000002, pqac-00000008, pqac-00000014) |
| Autoimmunity / ALPS-like phenotype | Autoimmune hemolytic anemia, thrombocytopenia, polyarthritis, lymphadenopathy, hepatosplenomegaly, elevated double-negative T cells, and ALPS-like presentations extend the phenotype. Fas-mediated apoptosis was reportedly intact. Frequency: not quantified in retrieved sources. | Childhood to adolescence; variable, relapsing or persistent immune dysregulation. | HP:0001890 Autoimmune hemolytic anemia; HP:0001744 Splenomegaly; HP:0002716 Lymphadenopathy; HP:0001945 Fever; HP:0012649 Autoimmunity | (pqac-00000004, pqac-00000005) |
| Cardiac defects | Structural cardiac anomalies are reported, including atrial septal defect, patent foramen ovale, valvular insufficiency, and pulmonary valve stenosis. Frequency: not quantified in retrieved sources. | Congenital/childhood-recognized; generally non-progressive structural findings. | HP:0001631 Atrial septal defect; HP:0001653 Patent foramen ovale; HP:0001642 Pulmonary valve stenosis | (pqac-00000001, pqac-00000006, pqac-00000005, pqac-00000016) |
| Hypothyroidism / short stature | One STK4-deficient child had hypothyroidism and short stature as part of the broader syndromic presentation. Frequency: not quantified in retrieved sources. | Childhood; chronic. | HP:0000821 Hypothyroidism; HP:0004322 Short stature | (pqac-00000013) |
| CD4 lymphopenia | Profound CD4+ T-cell lymphopenia is among the most consistent laboratory hallmarks; values in retrieved reports include very low absolute CD4 counts and reduced naive CD4 subsets. | Usually detected in childhood; chronic/persistent. | HP:0005403 CD4 lymphocytopenia; HP:0011839 Abnormality of T cell count | (pqac-00000001, pqac-00000004, pqac-00000005, pqac-00000008, pqac-00000011, pqac-00000012) |
| T- and B-cell lymphopenia | Combined T- and B-cell lymphopenia is frequently described, though severity is variable and some cases retain a near-normal CD19+ fraction. Frequency: not quantified in retrieved sources. | Childhood onset; chronic. | HP:0001888 Lymphopenia; HP:0005404 B lymphocytopenia; HP:0011839 Abnormality of T cell count | (pqac-00000001, pqac-00000006, pqac-00000007, pqac-00000011, pqac-00000014) |
| Dysgammaglobulinemia | Immunoglobulin abnormalities are variable, including hypergammaglobulinemia, low IgG2/poor vaccine responses, elevated IgM, hypogammaglobulinemia, or dysregulated immunoglobulin levels. Frequency: not quantified in retrieved sources. | Variable across childhood/adolescence; chronic. | HP:0004313 Decreased circulating IgG level; HP:0010783 Elevated circulating IgM level; HP:0010701 Abnormality of immune system physiology | (pqac-00000004, pqac-00000005, pqac-00000007, pqac-00000012, pqac-00000013) |
| Neutropenia | Intermittent or persistent neutropenia is repeatedly reported; sometimes accompanied by apparently normal marrow maturation. Frequency: not quantified in retrieved sources. | Usually childhood onset; intermittent/fluctuating in several reports. | HP:0001875 Neutropenia; HP:0001889 Frequent infections | (pqac-00000001, pqac-00000006, pqac-00000007, pqac-00000008) |
| Double-negative T-cell expansion / ALPS-like immunophenotype | Elevated TCRαβ+ CD4-CD8- double-negative T cells were reported in ALPS-like patients. Frequency: not quantified in retrieved sources. | Childhood/adolescent presentation; persistent in reported cases. | HP:0033079 Increased double negative T cells; HP:0012649 Autoimmunity | (pqac-00000004, pqac-00000005) |
| γδ T-cell expansion | Expanded γδ T-cell populations, including Vδ2+ γδ T-cell predominance, have been described and may represent a compensatory antiviral response. One 2024 report states γδ T-cell expansion has frequently been observed among 33 reported cases. | Can be recognized in adulthood as well as earlier disease; chronic. | HP:0011832 Abnormal lymphocyte physiology; HP:0011839 Abnormality of T cell count | (pqac-00000017) |
| Naive T-cell depletion / increased apoptosis | Beyond numeric lymphopenia, patients show marked loss of naïve T cells with increased apoptosis and defective T-cell survival. Frequency: not quantified in retrieved sources. | Chronic immunologic abnormality from childhood onward. | HP:0011839 Abnormality of T cell count; HP:0030783 Increased lymphocyte apoptosis | (pqac-00000011, pqac-00000012, pqac-00000014) |
| Defective leukocyte adhesion / chemotaxis | Functional phenotype includes impaired chemotaxis and adhesion (e.g., deficient CXCL11 responses, impaired ICAM-1/LFA-1 binding), relevant to host defense and trafficking. Frequency: not quantified in retrieved sources. | Chronic cellular defect; detected on functional testing rather than routine clinical exam. | HP:0012640 Abnormal leukocyte chemotaxis; HP:0011893 Abnormal leukocyte function | (pqac-00000012, pqac-00000014) |


*Table: This table summarizes the major clinical and laboratory phenotypes reported for STK4 deficiency, along with likely HPO mappings and supporting citations from the retrieved evidence. It is useful as a KB-ready phenotype scaffold when frequencies are incompletely quantified in the available primary reports.*