Typically, diagnosis involves several preliminary tests of immune function, including basic evaluation of the humoral immune system and the cell-mediated immune system. A WBC differential will reveal extremely elevated levels of neutrophils (on the order of 6-10x normal) because they are unable to leave the blood vessels.

In the case of LAD-I, specific diagnosis is done by flow cytometry. This technique will reveal absent or reduced CD18 expression in the leukocyte membrane. Recently, prenatal diagnosis systems has been established, allowing an early detection of the disease.

LAD-II diagnosis includes the study of different glycosilated forms of the transferrin protein. In LAD-III, as platelet function is also affected, this could be used to differentiate it from the other types.

The diagnosis is confirmed by bone marrow smears that show "giant inclusion bodies" in the cells that develop into white blood cells (leukocyte precursor cells). CHS can be diagnosed prenatally by examining a sample of hair from a fetal scalp biopsy or testing leukocytes from a fetal blood sample.

Under light microscopy the hairs present evenly distributed, regular melanin granules, larger than those found in normal hairs. Under polarized light microscopy these hairs exhibit a bright and polychromatic refringence pattern.

In terms of genetic testing, while it is done for "type 1" of this condition, "type 2" will only render (or identify) those genes which place the individual at higher risk. Other methods/exam to ascertain if an individual has autoimmune polyendocrine syndrome type 2 are:

- CT scan

- MRI

- Ultrasound

In many cases, MHA requires no treatment. However, in extreme cases, blood platelet transfusions may be necessary

Flow cytometry with monoclonal antibodies is used to screen for deficiencies of CD18.

Management of autoimmune polyendocrine syndrome type 2 consists of the following:

The basic tests performed when an immunodeficiency is suspected should include a full blood count (including accurate lymphocyte and granulocyte counts) and immunoglobulin levels (the three most important types of antibodies: IgG, IgA and IgM).

Other tests are performed depending on the suspected disorder:

- Quantification of the different types of mononuclear cells in the blood (i.e. lymphocytes and monocytes): different groups of T lymphocytes (dependent on their cell surface markers, e.g. CD4+, CD8+, CD3+, TCRαβ and TCRγδ), groups of B lymphocytes (CD19, CD20, CD21 and Immunoglobulin), natural killer cells and monocytes (CD15+), as well as activation markers (HLA-DR, CD25, CD80 (B cells).

- Tests for T cell function: skin tests for delayed-type hypersensitivity, cell responses to mitogens and allogeneic cells, cytokine production by cells

- Tests for B cell function: antibodies to routine immunisations and commonly acquired infections, quantification of IgG subclasses

- Tests for phagocyte function: reduction of nitro blue tetrazolium chloride, assays of chemotaxis, bactericidal activity.

Due to the rarity of many primary immunodeficiencies, many of the above tests are highly specialised and tend to be performed in research laboratories.

Criteria for diagnosis were agreed in 1999. For instance, an antibody deficiency can be diagnosed in the presence of low immunoglobulins, recurrent infections and failure of the development of antibodies on exposure to antigens. The 1999 criteria also distinguish between "definitive", "probable" and "possible" in the diagnosis of primary immunodeficiency. "Definitive" diagnosis is made when it is likely that in 20 years, the patient has a >98% chance of the same diagnosis being made; this level of diagnosis is achievable with the detection of a genetic mutation or very specific circumstantial abnormalities. "Probable" diagnosis is made when no genetic diagnosis can be made, but the patient has all other characteristics of a particular disease; the chance of the same diagnosis being made 20 years later is estimated to be 85-97%. Finally, a "possible" diagnosis is made when the patient has only some of the characteristics of a disease are present, but not all.

There are several manifestations of Chédiak–Higashi syndrome as mentioned above; however, neutropenia seems to be the most common. The syndrome is associated with oculocutaneous albinism. Persons are prone for infections, especially with "Staphylococcus aureus", as well as "Streptococci".

It is associated with periodontal disease of the deciduous dentition. Associated features include abnormalities in melanocytes (albinism), nerve defects, bleeding disorders.

A 2009 study reported results from 36 children who had received a stem cell transplant. At the time of follow-up (median time 62 months), 75% of the children were still alive.

Anomalies resembling Pelger–Huët anomaly that are acquired rather than congenital have been described as pseudo Pelger–Huët anomaly. These can develop in the course of acute myelogenous leukemia or chronic myelogenous leukemia and in myelodysplastic syndrome. It has also been described in Filovirus disease.

In patients with these conditions, the pseudo–Pelger–Huët cells tend to appear late in the disease and often appear after considerable chemotherapy has been administered. The morphologic changes have also been described in myxedema associated with panhypopituitarism, vitamin B12 and folate deficiency, multiple myeloma, enteroviral infections, malaria, muscular dystrophy, leukemoid reaction secondary to metastases to the bone marrow, and drug sensitivity, sulfa and valproate toxicities are examples. In some of these conditions, especially the drug-induced cases, identifying the change as Pelger–Huët anomaly is important because it obviates the need for further unnecessary testing for cancer.

Peripheral blood smear shows a predominance of neutrophils with bilobed nuclei which are composed of two nuclear masses connected with a thin filament of chromatin. It resembles the pince-nez glasses, so it is often referred to as pince-nez appearance. Usually the congenital form is not associated with thrombocytopenia and leukopenia, so if these features are present more detailed search for myelodysplasia is warranted, as pseudo-Pelger–Huët anomaly can be an early feature of myelodysplasia.

Because the CD18 gene has been cloned and sequenced, this disorder is a potential candidate for gene therapy.

Bone marrow transplant may be possible for Severe Combined Immune Deficiency and other severe immunodeficiences.

Virus-specific T-Lymphocytes (VST) therapy is used for patients who have received hematopoietic stem cell transplantation that has proven to be unsuccessful. It is a treatment that has been effective in preventing and treating viral infections after HSCT. VST therapy uses active donor T-cells that are isolated from alloreactive T-cells which have proven immunity against one or more viruses. Such donor T-cells often cause acute graft-versus-host disease (GVHD), a subject of ongoing investigation. VSTs have been produced primarily by ex-vivo cultures and by the expansion of T-lymphocytes after stimulation with viral antigens. This is carried out by using donor-derived antigen-presenting cells. These new methods have reduced culture time to 10–12 days by using specific cytokines from adult donors or virus-naive cord blood. This treatment is far quicker and with a substantially higher success rate than the 3–6 months it takes to carry out HSCT on a patient diagnosed with a primary immunodeficiency. T-lymphocyte therapies are still in the experimental stage; few are even in clinical trials, none have been FDA approved, and availability in clinical practice may be years or even a decade or more away.

Is a benign dominantly inherited defect of terminal neutrophil differentiation as a result of mutations in the lamin B receptor gene. The characteristic leukocyte appearance was first reported in 1928 by Karel Pelger (1885-1931), a Dutch Hematologist, who described leukocytes with dumbbell-shaped bilobed nuclei, a reduced number of nuclear segments, and coarse clumping of the nuclear chromatin. In 1931, Gauthier Jean Huet (1879-1970), a Dutch Pediatrician, identified it as an inherited disorder.

It is a genetic disorder with an autosomal dominant inheritance pattern. Heterozygotes are clinically normal, although their neutrophils may be mistaken for immature cells, which may cause mistreatment in a clinical setting. Homozygotes tend to have neutrophils with rounded nuclei that do have some functional problems. Homozygous individuals inconsistently have skeletal anomalies such as post-axial polydactyly, short metacarpals, short upper limbs, short stature, or hyperkyphosis.

Identifying Pelger–Huët anomaly is important to differentiate from bandemia with a left-shifted peripheral blood smear and neutrophilic band forms and from an increase in young neutrophilic forms that can be observed in association with infection.

In the leukocytes, the presence of very small rods (around 3 micrometers), or Döhle-like bodies can be seen in the cytoplasm.

A normal eosinophil count is considered to be less than 0.65/L. Eosinophil counts are higher in newborns and vary with age, time (lower in the morning and higher at night), exercise, environment, and exposure to allergens. Eosinophilia is never a normal lab finding. Efforts should always be made to discover the underlying cause, though the cause may not always be found.

Congenital disorder of glycosylation type IIc or Leukocyte adhesion deficiency-2 (LAD2) is a type of leukocyte adhesion deficiency attributable to the absence of neutrophil sialyl-LewisX, a ligand of P- and E-selectin on vascular endothelium. It is associated with "SLC35C1".

This disorder was discovered in two unrelated Israeli boys 3 and 5 years of age, each the offspring of consanguineous parents. Both had severe mental retardation, short stature, a distinctive facial appearance, and the Bombay (hh) blood phenotype, and both were secretor- and Lewis-negative. They both had had recurrent severe bacterial infections similar to those seen in patients with LAD1, including pneumonia, peridontitis, otitis media, and localized cellulitis. Similar to that in patients with LAD1, their infections were accompanied by pronounced leukocytosis (30,000 to 150,000/mm) but an absence of pus formation at sites of recurrent cellulitis. In vitro studies revealed a pronounced defect in neutrophil motility. Because the genes for the red blood cell H antigen and for the secretor status encode for distinct α1,2-fucosyltransferases and the synthesis of Sialyl-LewisX requires an α1,3-fucosyltransferase, it was postulated that a general defect in fucose metabolism is the basis for this disorder. It was subsequently found that GDP-L-fucose transport into Golgi vesicles was specifically impaired, and then missense mutations in the GDP-fucose transporter cDNA of three patients with LAD2 were discovered. Thus, GDP-fucose transporter deficiency is a cause of LAD2.

The complete blood cell count is a blood panel that includes the overall WBC count and various subsets such as the absolute neutrophil count. Reference ranges for blood tests specify the typical counts in healthy people.

TLC- (Total leucocyte count):

Normal TLC in an adult person is 6000-8000WBC/mm^3 of blood.

DLC- (Differential leucocyte count):

Number/ (%) of different type of leucocyte in per cubic mm. of blood.

Fechtner syndrome is a variant of Alport syndrome characterized by leukocyte inclusions, macrothrombocytopenia, thrombocytopenia, nephritis, and sensorineural hearing loss. Some patients may also develop cataracts.

A clinical diagnosis of SCS can be verified by testing the TWIST1 gene (only gene in which mutations are known to cause SCS) for mutations using DNA analysis, such as sequence analysis, deletion/duplication analysis, and cytogenetics/ FISH analysis. Sequence analysis of exon 1 (TWIST1 coding region) provides a good method for detecting the frequency of mutations in the TWIST1 gene. These mutations include nonsense, missense, splice site mutation, and intragenic deletions/insertions. Deletion/duplication analysis identifies mutations in the TWIST1 gene that are not readily detected by sequence analysis. Common methods include PCR, multiplex ligation-dependent probe amplification (MLPA), and chromosomal microarray (CMA). Cytogenetic/FISH analysis attaches fluorescently labels DNA markers to a denatured chromosome and is then examined under fluorescent lighting, which reveals mutations caused by translocations or inversions involving 7p21. Occasionally, individuals with SCS have a chromosome translocation, inversion, or ring chromosome 7 involving 7p21 resulting in atypical findings, such as, increased developmental delay. Individuals with SCS, typically have normal brain functioning and rarely have mental impairments. For this reason, if an individual has both SCS and mental retardation, then they should have their TWIST1 gene screened more carefully because this is not a normal trait of SCS. Cytogenetic testing and direct gene testing can also be used to study gene/chromosome defects. Cytogenetic testing is the study of chromosomes to detect gains or losses of chromosomes or chromosome segments using fluorescent in situ hybridization (FISH) and/or comparative genomic hybridization (CGH). Direct gene testing uses blood, hair, skin, amniotic fluid, or other tissues in order to find genetic disorders. Direct gene testing can determine whether an individual has SCS by testing the individual's blood for mutations in the TWIST1 gene.

1. Blood. With Pearson Syndrome, the bone marrow fails to produce white blood cells called neutrophils. The syndrome also leads to anemia, low platelet count, and aplastic anemia It may be confused with transient erythroblastopenia of childhood.

2. Pancreas. Pearson Syndrome causes the exocrine pancreas to not function properly because of scarring and atrophy

Individuals with this condition have difficulty absorbing nutrients from their diet which leads to malabsorption. infants with this condition generally do not grow or gain weight.

Up until recently, experts frequently disagreed on whether a patient had SCS, Crouzon syndrome, isolated craniosynostosis, or some other disease because the symptoms are so closely related, they literally had no way of differentiating between all of them. However, we now have direct gene testing, which allows for a more definitive diagnosis because it allows them to be differentiated from each other based on which gene is mutated in each condition. The following is a list of conditions commonly confused/misdiagnosed for SCS, some of their symptoms, and which mutated gene each contains:

No treatment is available for most of these disorders. Mannose supplementation relieves the symptoms in PMI-CDG (CDG-Ib) for the most part, even though the hepatic fibrosis may persist. Fucose supplementation has had a partial effect on some SLC35C1-CDG (CDG-IIc or LAD-II) patients.

Pearson Marrow Pancreas Syndrome (PMPS) is a condition that presents itself with severe reticulocyto-penic anemia.

With the pancreas not functioning properly, this leads to high levels of fats in the liver. PMPS can also lead to diabetes and scarring of the pancreas.

Conventionally, a leukocytosis exceeding 50,000 WBC/mm with a significant increase in early neutrophil precursors is referred to as a leukemoid reaction. The peripheral blood smear may show myelocytes, metamyelocytes, promyelocytes, and rarely myeloblasts; however, there is a mix of early mature neutrophil precursors, in contrast to the immature forms typically seen in acute leukemia. Serum leukocyte alkaline phosphatase is normal or elevated in leukemoid reaction, but is depressed in chronic myelogenous leukemia. The bone marrow in a leukemoid reaction, if examined, may be hypercellular but is otherwise typically unremarkable.

Leukemoid reactions are generally benign and are not dangerous in and of themselves, although they are often a response to a significant disease state (see "Causes" below). However, leukemoid reactions can resemble more serious conditions such as chronic myelogenous leukemia (CML), which can present with identical findings on peripheral blood smear.

Historically, various clues including the leukocyte alkaline phosphatase score and the presence of basophilia were used to distinguish CML from a leukemoid reaction. However, at present the test of choice in adults to distinguish CML is an assay for the presence of the Philadelphia chromosome, either via cytogenetics and FISH, or via PCR for the BCR/ABL fusion gene. The LAP (Leukocyte Alkaline Phosphatase) score is high in reactive states but is low in CML. In cases where the diagnosis is uncertain, a qualified hematologist or oncologist should be consulted.

Below are blood reference ranges for various types leucocytes/WBCs. The 97.5 percentile (right limits in intervals in image, showing 95% prediction intervals) is a common limit for defining leukocytosis.