- Decreased circulating IgM concentration (HP:0002850): An abnormally decreased level of immunoglobulin M (IgM) in blood. Evidence: PCS. Frequency: 2/4. (PMID:22390233;PMID:37584719)
- Recurrent Candida infection (HP:0005401): Increased susceptibility to Candida infections as manifested by recurrent episodes of Candida infection. Evidence: PCS. Frequency: 1/1. (PMID:22390233)
- Protracted diarrhea (HP:0004385). Evidence: PCS. Frequency: 3/3. (PMID:37584719)
- Hypotonia (HP:0001252): Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist. Evidence: PCS. Frequency: 2/3. (PMID:37584719)
- Global developmental delay (HP:0001263): A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age. Evidence: PCS. Frequency: 1/3. (PMID:37584719)
- Hepatomegaly (HP:0002240): Abnormally increased size of the liver. Evidence: PCS. Frequency: 1/4. (PMID:22390233;PMID:37584719)
- Ataxia (HP:0001251): Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). Evidence: PCS. Frequency: 1/3. (PMID:37584719)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 3/4. (PMID:22390233;PMID:37584719)
- Brain atrophy (HP:0012444): Partial or complete wasting (loss) of brain tissue that was once present. Evidence: PCS. Frequency: 1/1. (PMID:37584719)
- Decreased total CD4+ T cell proportion (HP:0032218): Abnormal decrease of helper CD3+CD4+ T cells, measured as percentage of total CD3+ T cells in the blood, compared to a reference range for a given sex and age-group. These are usually measured within the TCR alpha/beta positive population. Evidence: PCS. Frequency: 4/4. (PMID:22390233;PMID:37584719)
- Failure to thrive (HP:0001508): Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm. Evidence: PCS. Frequency: 2/3. (PMID:37584719)
- Lower limb muscle weakness (HP:0007340): Weakness of the muscles of the legs. Evidence: PCS. Frequency: 1/3. (PMID:37584719)
- Inverted CD4:CD8 ratio (HP:0033222): CD4:CD8 ratio less than 1, measured either as proportion of total CD3+ T cells, or in absolute numbers per microliter. These are usually measured within the TCR alpha/beta positive population. Normally there are relatively more CD4+ than CD8+ T cells. Evidence: PCS. Frequency: 3/3. (PMID:37584719)
- Impaired phytohemagglutinin-induced T lymphocyte transformation (HP:0025834): Def: A reduced rate of T lymphocyte transformation in response to in vitro stimulation to the mitogen phytohemagglutinin (PHA). Following PHA stimulation, T cells normally undergo morphological and biochemical alterations that reflect the transformation into lymphoblasts. There are several methods for quantifying this effect including measuring the uptake of the radioactive marker 3H-TdR, methyl thiazolyl tetrazolium colorimetric analysis (MTT assay), and morphological examination under the microscope or using a hematology analyzer. Various types of stimulation index compare the amount of proliferation between treated and control cells. An impaired test refers to a result in which the amount of stimulation is subnormal. Evidence: PCS. Frequency: 1/1. (PMID:22390233)
- Recurrent otitis media (HP:0000403): Increased susceptibility to otitis media, as manifested by recurrent episodes of otitis media. Evidence: PCS. Frequency: 0/3. (PMID:37584719)
- Autosomal recessive inheritance (HP:0000007): A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele). Evidence: PCS. (PMID:37584719)
- Postnatal growth retardation (HP:0008897): Slow or limited growth after birth. Evidence: PCS. Frequency: 1/1. (PMID:22390233)
- Recurrent pneumonia (HP:0006532): An increased susceptibility to pneumonia as manifested by a history of recurrent episodes of pneumonia. Evidence: PCS. Frequency: 3/3. (PMID:37584719)
- Decreased circulating IgA concentration (HP:0002720): Decreased levels of immunoglobulin A (IgA). Evidence: PCS. Frequency: 4/4. (PMID:22390233;PMID:37584719)
- Splenomegaly (HP:0001744): Abnormal increased size of the spleen. Evidence: PCS. Frequency: 1/1. (PMID:22390233)
- Decreased circulating IgG concentration (HP:0004315): An abnormally decreased level of immunoglobulin G (IgG) in blood. Evidence: PCS. Frequency: 4/4. (PMID:22390233;PMID:37584719)
- Decreased total neutrophil count (HP:0001875): Abnormal decrease of absolute number of neutrophils in the blood, per microlitre, compared to a reference range for a given sex and age-group. Evidence: PCS. Frequency: 1/3. (PMID:37584719)
- Neonatal onset (HP:0003623): Onset of signs or symptoms of disease within the first 28 days of life. Evidence: PCS. Frequency: 1/3. (PMID:37584719)
These phenotypes are associated with the disease MHC class II deficiency 4 (OMIM:620817).