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.

People with CHS have light skin and silvery hair (albinism) and frequently complain of solar sensitivity and photophobia. Other signs and symptoms vary considerably, but frequent infections and neuropathy are common. The infections involve mucous membranes, skin, and the respiratory tract. Affected children are susceptible to infection by Gram-positive and gram-negative bacteria and fungi, with "Staphylococcus aureus" being the most common infection cause. Infections in CHS patients tend to be very serious and even life-threatening. Neuropathy often begins in the teenage years and becomes the most prominent problem. Few patients with this condition live to adulthood.

Most children with Chédiak–Higashi syndrome ultimately reach a stage known as the "accelerated phase", or the "lymphoma-like syndrome", in which defective white blood cells divide uncontrollably and invade many of the body's organs. The accelerated phase is associated with fever, episodes of abnormal bleeding, overwhelming infections, and organ failure. These medical problems are usually life-threatening in childhood.

LAD was first recognized as a distinct clinical entity in the 1970s. The classic descriptions of LAD included recurrent bacterial infections, defects in neutrophil adhesion, and a delay in umbilical cord sloughing. The adhesion defects result in poor leukocyte chemotaxis, particularly neutrophil, inability to form pus and neutrophilia.

Individuals with LAD suffer from bacterial infections beginning in the neonatal period. Infections such as omphalitis, pneumonia, gingivitis, and peritonitis are common and often life-threatening due to the infant's inability to properly destroy the invading pathogens. These individuals do not form abscesses because granulocytes cannot migrate to the sites of infection.

The precise symptoms of a primary immunodeficiency depend on the type of defect. Generally, the symptoms and signs that lead to the diagnosis of an immunodeficiency include recurrent or persistent infections or developmental delay as a result of infection. Particular organ problems (e.g. diseases involving the skin, heart, facial development and skeletal system) may be present in certain conditions. Others predispose to autoimmune disease, where the immune system attacks the body's own tissues, or tumours (sometimes specific forms of cancer, such as lymphoma). The nature of the infections, as well as the additional features, may provide clues as to the exact nature of the immune defect.

Leukocyte adhesion deficiency (LAD), is a rare autosomal recessive disorder characterized by immunodeficiency resulting in recurrent infections. LAD is currently divided into three subtypes: LAD1, LAD2, and the recently described LAD3, also known as LAD-1/variant. In LAD3, the immune defects are supplemented by a Glanzmann thrombasthenia-like bleeding tendency.

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.

Chédiak–Higashi syndrome is a rare autosomal recessive disorder that arises from a mutation of a lysosomal trafficking regulator protein, which leads to a decrease in phagocytosis. The decrease in phagocytosis results in recurrent pyogenic infections, albinism and peripheral neuropathy. It occurs in humans, cattle, blue Persian cats, Australian blue rats, mice, mink, foxes, and the only known captive white orca.

Pelger–Huët anomaly (pronunciation: [pel′gər hyo̅o̅′ət]) is a blood laminopathy associated with the lamin B receptor.

It is characterized by a white blood cell type known as a neutrophil whose nucleus is hyposegmented.

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.

Laminopathies and other nuclear envelopathies have a large variety of clinical symptoms including skeletal and/or cardiac muscular dystrophy, lipodystrophy and diabetes, dysplasia, dermo- or neuropathy, leukodystrophy, and progeria (premature aging). Most of these symptoms develop after birth, typically during childhood or adolescence. Some laminopathies however may lead to an early death, and mutations of lamin B (LMNB1 gene) may be lethal before or at birth.

Primary immunodeficiencies are disorders in which part of the body's immune system is missing or does not function normally. To be considered a "primary" immunodeficiency, the cause of the immune deficiency must not be secondary in nature (i.e., caused by other disease, drug treatment, or environmental exposure to toxins). Most primary immunodeficiencies are genetic disorders; the majority are diagnosed in children under the age of one, although milder forms may not be recognized until adulthood. While there are over 100 recognized PIDs, most are very rare. About 1 in 500 people in the United States are born with a primary immunodeficiency. Immune deficiencies can result in persistent or recurring infections, autoinflammatory disorders, tumors, and disorders of various organs. There are currently no cures for these conditions; treatment is palliative and consists of managing infections and boosting the immune system.

Symptoms(and signs) that are consistent with this disorder are the following:

Autoimmune polyendocrine syndrome type 2, a form of autoimmune polyendocrine syndrome also known as Schmidt's syndrome, or APS-II, is the most common form of the polyglandular failure syndromes. It is heterogeneous and has not been linked to one gene. Rather, individuals are at a higher risk when they carry a particular human leukocyte antigen (HLA-DQ2, HLA-DQ8 and HLA-DR4). APS-II affects women to a greater degree than men.

People who are affected by Liebenberg Syndrome suffer from three main symptoms:

1. Dysplasia (improper formation) of the bony components of the elbow

2. Abnormal shape of carpal bones

3. Brachydactyly, a symptom where the fingers and toes are shorter than normal.

Laminopathies ("" + "") are a group of rare genetic disorders caused by mutations in genes encoding proteins of the nuclear lamina. They are included in the more generic term "nuclear envelopathies" that was coined in 2000 for diseases associated with defects of the nuclear envelope. Since the first reports of laminopathies in the late 1990s, increased research efforts have started to uncover the vital role of nuclear envelope proteins in cell and tissue integrity in animals.

Liebenberg Syndrome is a rare autosomal genetic disease that involves a deletion mutation upstream of the PITX1 gene, which is one that's responsible for the body's organization, specifically in forming lower limbs. In animal studies, when this deletion was introduced to developing birds, their wing buds were noted to take on limb-like structures.

The condition was first described by Dr. F. Liebenberg in 1973 while he followed multiple generations of a South African family, but it has since been noticed in other family lineages across the world.

The general presentation is of a skin-covered nodule, papule, or nodule of the skin surface, usually immediately anterior to the auricle. However, it may be anywhere within the periauricular tissues. Bilateral presentation can be seen.

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

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.

The several components or degrees of development range from an ear tag, preauricular appendage, preauricular tag, or accessory tragus, to supernumerary ears or polyotia. It is a relatively common congenital anomaly of the first branchial arch or second branchial arches. Other anomalies may be present concurrently, including cleft palate, cleft lip, or mandibular hypoplasia. There is a known association with Goldenhar syndrome (oculo-auriculo-vertebral syndrome) and with Wildervanck syndrome. There may also be an association with congenital cartilaginous rest of the neck.

Hypophosphatasia in childhood has variable clinical expression. As a result of defects in the development of the dental cementum, the deciduous teeth (baby teeth) are often lost fore the age of 5. Frequently, the incisors are lost first; occasionally all of the teeth are lost prematurely. Dental radiographs can show the enlarged pulp chambers and root canals that are characteristic of rickets.

Patients may experience delayed walking, a characteristic waddling gait, stiffness and pain, and muscle weakness (especially in the thighs) consistent with nonprogressive myopathy. Typically, radiographs show defects in calcification and characteristic bony defects near the ends of major long bones. Growth retardation, frequent fractures, and low bone density (osteopenia) are common. In severely-affected infants and young children, cranial bones can fuse prematurely, despite the appearance of open fontanels on radiographic studies. The illusion of open fontanels results from hypomineralization of large areas of the calvarium. Premature bony fusion of the cranial sutures may elevate intracranial pressure.

Infantile hypophosphatasia presents in the first 6 months of life, with the onset of poor feeding and inadequate weight gain. Clinical manifestations of rickets often appear at this time. Although cranial sutures appear to be wide, this reflects hypomineralization of the skull, and there is often “functional” craniosynostosis. If the patient survives infancy, these sutures can permanently fuse. Defects in the chest, such as flail chest resulting from rib fractures, lead to respiratory compromise and pneumonia. Elevated calcium in the blood (hypercalcemia) and urine (hypercalcenuria) are also common, and may explain the renal problems and recurrent vomiting seen is this disease.

Radiographic features in infants are generally less severe than those seen in perinatal hypophosphatasia. In the long bones, there is an abrupt change from a normal appearance in the shaft (diaphysis) to uncalcified regions near the ends (metaphysis), which suggests the occurrence of an abrupt metabolic change. In addition, serial radiography studies suggest that defects in skeletal mineralization (i.e. rickets) persist and become more generalized. Mortality is estimated to be 50% in the first year of life.

Acanthosis nigricans may present with thickened, velvety, relatively darker areas of skin on the neck, armpit and in skin folds.

May–Hegglin anomaly (MHA), also known as Döhle leukocyte inclusions with giant platelets and macrothrombocytopenia with leukocyte inclusions, is a rare genetic disorder of the blood platelets that causes them to be abnormally large.

Malignant acanthosis nigricans refers to acanthosis nigricans occurring as a paraneoplastic syndrome associated with a cancer. Malignant acanthosis nigricans is most commonly associated with gastrointestinal adenocarcinomas, as well as genitourinary cancers such as those of the prostate, breast, and ovary. Other cancers, such as those of the lung, stomach, and lymphoma, are occasionally associated with acanthosis nigricans.

This form of acanthosis nigricans is more likely to involve mucous membranes (25-50% of cases) Malignant acanthosis nigricans that may either precede (18%), accompany (60%), or follow (22%) the onset of an internal cancer. Malignancy-associated acanthosis nigricans is usually rapid in onset and may be accompanied by skin tags, multiple seborrheic keratoses, or tripe palms.

An osteoclast (from the Greek words for "bone" (ὀστέον), and "broken" (κλαστός)) is a type of bone cell that breaks down bone tissue. This function is critical in the maintenance, repair, and remodelling of bones of the vertebral skeleton. The osteoclast disassembles and digests the composite of hydrated protein and mineral at a molecular level by secreting acid and a collagenase, a process known as "bone resorption". This process also helps regulate the level of blood calcium.

An odontoclast (/odon·to·clast/; o-don´to-klast) is an osteoclast associated with absorption of the roots of deciduous teeth.