Miller-Dieker occurs in less than one in 100000 people and can occur in all races.

Most individuals with this condition do not survive beyond childhood. Individuals with MDS usually die in infancy and therefore do not live to the age where they can reproduce and transmit MDS to their offspring.

Wolf–Hirschhorn syndrome is a microdeletion syndrome caused by a deletion within HSA band 4p16.3 of the short arm of chromosome 4, particularly in the region of and . About 87% of cases represent a "de novo" deletion, while about 13% are inherited from a parent with a chromosome translocation. In the cases of familial translocation, there is a 2 to 1 excess of maternal transmission. Of the "de novo" cases, 80% are paternally derived. Severity of symptoms and expressed phenotype differ based on the amount of genetic material deleted. The critical region for determining the phenotype is at 4p16.3 and can often be detected through genetic testing and fluorescence in situ hybridization (FISH). Genetic testing and genetic counseling is offered to affected families.

McKusick–Kaufman syndrome is a genetic condition associated with MKKS.

The condition is named for Dr. Robert L. Kaufman and Victor McKusick. It is sometimes known by the abbreviation MKS. In infancy it can be difficult to distinguish between MKS and the related Bardet–Biedl syndrome, as the more severe symptoms of the latter condition rarely materialise before adulthood.

The most common characteristics include a distinct craniofacial phenotype (microcephaly, micrognathia, short philtrum, prominent glabella, ocular hypertelorism, dysplastic ears and periauricular tags), growth restriction, intellectual disability, muscle hypotonia, seizures, and congenital heart defects. Less common characteristics include hypospadias, colobomata of the iris, renal anomalies, and deafness. Antibody deficiencies are also common, including common variable immunodeficiency and IgA deficiency. T-cell immunity is normal.

There is no specific treatment for micro syndrome, but there are ways to help the disorders, and illnesses that come with it. Many individuals with Micro Syndrome need permanent assistance from their disorders and inabilities to move and support themselves. Seizures are not uncommon and patients should get therapy to help control them, and many patients also require wheelchairs to move, so an assistant would be needed at all times.

Those with micro syndrome are born appearing normal. At the age of one, mental and physical delays become apparent, along with some limb spasms. By the age of eight micro syndrome has already set in, and the patient will have joint contractures, Ocular Atrophy will become noticeable, the patient will most likely lose ability to walk, speak, and sometimes move at all.

The rare cases that have been examined are often within families, or the people that have cases of micro syndrome have a mutation in their genes.

It can be associated with "RAB3GAP".

Clinically, McKusick–Kaufman syndrome is characterized by a combination of three features: postaxial polydactyly, heart defects, and genital abnormalities:

- Vaginal atresia with hydrometrocolpos

- Double vagina and/or uterus.

- Hypospadias, chordee (a downward-curving penis), and undescended testes (cryptorchidism).

- ureter stenosis or ureteric atresia

Chromosomal deletion syndromes result from deletion of parts of chromosomes. Depending on the location, size, and whom the deletion is inherited from, there are a few known different variations of chromosome deletions. Chromosomal deletion syndromes typically involve larger deletions that are visible using karyotyping techniques. Smaller deletions result in Microdeletion syndrome, which are detected using fluorescence in situ hybridization (FISH)

Examples of chromosomal deletion syndromes include 5p-Deletion (cri du chat syndrome), 4p-Deletion (Wolf-Hirschhorn syndrome), Prader–Willi syndrome, and Angelman syndrome.

Smith–Magenis syndrome is a chromosomal condition related to low copy repeats of specific segments of chromosome 17. Most people with SMS have a deletion of genetic material from a specific region of chromosome 17 (17p11.2). Although this region contains multiple genes, recently researchers discovered that the loss of one particular gene the retinoic acid induced 1 or "RAI1" is responsible for most of the characteristic features of this condition. Also, other genes within the chromosome 17 contribute to the variability and severity of the clinical features. The loss of other genes in the deleted region may help explain why the features of Smith–Magenis syndrome vary among affected individuals. A small percentage of people with Smith–Magenis syndrome have a mutation in the "RAI1" gene instead of a chromosomal deletion.

These deletions and mutations lead to the production of an abnormal or nonfunctional version of the "RAI1" protein. "RAI1" is a transcription factor that regulates the expression of multiple genes, including several that are involved in controlling circadian rhythm, such as "CLOCK". The groups led by James Lupski (Baylor College of Medicine) and Sarah Elsea (Virginia Commonwealth University) are in the process of studying the exact function of this gene in relation to Smith Magenis Syndrome.

SMS is typically not inherited. This condition usually results from a genetic change that occurs during the formation of reproductive cells (eggs or sperm) or in early fetal development. People with Smith–Magenis syndrome most often have no history of the condition in their family.

Approximately 4% of the general population have an elongated styloid process, and of these about 4% give rise to the symptoms of Eagle syndrome. Therefore, the incidence of stylohyoid syndrome may be about 0.16%.

Patients with this syndrome tend to be between 30 and 50 years of age but it has been recorded in teenagers and in patients > 75 years old. It is more common in women, with a male:female ratio ~ 1:2.

Smith–Magenis Syndrome (SMS) is a genetic disorder with features including intellectual disability, facial abnormalities, difficulty sleeping, and numerous behavioral problems such as self-harm. Smith–Magenis syndrome affects an estimated between 1 in 15,000 to 1 in 25,000 individuals.

It is a microdeletion syndrome characterized by an abnormality in the short (p) arm of chromosome 17 and is sometimes called the 17p- syndrome.

Genetic

- Inborn errors of metabolism

1. Congenital disorder of glycosylation

2. Mitochondrial disorders

3. Peroxisomal disorder

4. Glucose transporter defect

5. Menkes disease

6. Congenital disorders of amino acid metabolism

7. Organic acidemia

Syndromes

- Contiguous gene deletion

1. 17p13.3 deletion (Miller–Dieker syndrome)

- Single gene defects

1. Rett syndrome (primarily girls)

2. Nijmegen breakage syndrome

3. X-linked lissencephaly with abnormal genitalia

4. Aicardi–Goutières syndrome

5. Ataxia telangiectasia

6. Cohen syndrome

7. Cockayne syndrome

Acquired

- Disruptive injuries

1. Traumatic brain injury

2. Hypoxic-ischemic encephalopathy

3. Ischemic stroke

4. Hemorrhagic stroke

- Infections

1. Congenital HIV encephalopathy

2. Meningitis

3. Encephalitis

- Toxins

1. Lead poisoning

2. Chronic renal failure

- Deprivation

1. Hypothyroidism

2. Anemia

3. Congenital heart disease

4. Malnutrition

Genetic factors may play a role in causing some cases of microcephaly. Relationships have been found between autism, duplications of chromosomes, and macrocephaly on one side. On the other side, a relationship has been found between schizophrenia, deletions of chromosomes, and microcephaly. Moreover, an association has been established between common genetic variants within known microcephaly genes ("MCPH1, CDK5RAP2") and normal variation in brain structure as measured with magnetic resonance imaging (MRI)i.e., primarily brain cortical surface area and total brain volume.

The spread of Aedes mosquito-borne Zika virus has been implicated in increasing levels of congenital microcephaly by the International Society for Infectious Diseases and the US Centers for Disease Control and Prevention. Zika can spread from a pregnant woman to her fetus. This can result in other severe brain malformations and birth defects. A study published in The New England Journal of Medicine has documented a case in which they found evidence of the Zika virus in the brain of a fetus that displayed the morphology of microcephaly.

Isolated

1. Familial (autosomal recessive) microcephaly

2. Autosomal dominant microcephaly

3. X-linked microcephaly

4. Chromosomal (balanced rearrangements and ring chromosome)

Syndromes

- Chromosomal

1. Poland syndrome

2. Down syndrome

3. Edward syndrome

4. Patau syndrome

5. Unbalanced rearrangements

- Contiguous gene deletion

1. 4p deletion (Wolf–Hirschhorn syndrome)

2. 5p deletion (Cri-du-chat)

3. 7q11.23 deletion (Williams syndrome)

4. 22q11 deletion (DiGeorge syndrome)

- Single gene defects

1. Smith–Lemli–Opitz syndrome

2. Seckel syndrome

3. Cornelia de Lange syndrome

4. Holoprosencephaly

5. Primary microcephaly 4

6. Wiedemann-Steiner syndrome

Acquired

- Disruptive injuries

1. Ischemic stroke

2. Hemorrhagic stroke

3. Death of a monozygotic twin

- Vertically transmitted infections

1. Congenital cytomegalovirus infection

2. Toxoplasmosis

3. Congenital rubella syndrome

4. Zika virus

- Drugs

1. Fetal hydantoin syndrome

2. Fetal alcohol syndrome

Other

1. Radiation exposure to mother

2. Maternal malnutrition

3. Maternal phenylketonuria

4. Poorly controlled gestational diabetes

5. Hyperthermia

6. Maternal hypothyroidism

7. Placental insufficiency

Microstomia ("micro-" a combining form meaning small + "-stomia" a combining form meaning mouth = (abnormally) "small mouth") is a clinical feature of many craniofacial syndromes, including Freeman-Sheldon syndrome and Sheldon-Hall syndromes (or distal arthrogryposis multiplex congenita). It may present with whistling-face feature, as well, as in Freeman-Sheldon syndrome. In this syndrome, it impairs alimentation and may require repeated oral surgeries (called commissurotomy) to improve function.

It can also be a feature of systemic scleroderma.

Kostmann syndrome is a group of diseases that affect myelopoiesis, causing a congenital form of neutropenia (severe congenital neutropenia [SCN]), usually without other physical malformations. SCN manifests in infancy with life-threatening bacterial infections.

Most cases of SCN respond to treatment with granulocyte colony-stimulating factor (filgrastim), which increases the neutrophil count and decreases the severity and frequency of infections. Although this treatment has significantly improved survival, people with SCN are at risk of long-term complications such as hematopoietic clonal disorders (myelodysplastic syndrome, acute myeloid leukemia).

Kostmann disease (SCN3), the initial subtype recognized, was clinically described in 1956. This type has an autosomal recessive inheritance pattern, whereas the most common subtype of Kostmann syndrome, SCN1, shows autosomal dominant inheritance.

The various mutations may be responsible for the untimely initiation of apoptosis in myelocytes, producing their premature destruction. There may be, in addition, other underlying molecular/genetic changes producing DNA mutations and genome instability, which contribute to initiation and progression of this disease.

Prader-WIlli (PWS) and Angelman syndrome (AS) are distinct neurogenetic disorders caused by chromosomal deletions, uniparental disomy or loss of the imprinted gene expression in the 15q11-q13 region. Whether an individual exhibits PWS or AS depends on if there is a lack of the paternally expressed gene to contribute to the region.

PWS is frequently found to be the reason for secondary obesity due to early onset hyperphagia - the abnormal increase in appetite for consumption of food.There are known three molecular causes of Prader–Willi syndrome development. One of them consists in micro-deletions of the chromosome region 15q11–q13. 70% of patients present a 5–7-Mb "de novo" deletion in the proximal region of the paternal chromosome 15. The second frequent genetic abnormality (~ 25–30% of cases) is maternal uniparental disomy of chromosome 15. The mechanism is due to maternal meiotic non-disjunction followed by mitotic loss of the paternal chromosome 15 after fertilization. The third cause for PWS is the disruption of the imprinting process on the paternally inherited chromosome 15 (epigenetic phenomena). This disruption is present in approximately 2–5% of affected individuals. Less than 20% of individuals with an imprinting defect are found to have a very small deletion in the PWS imprinting centre region, located at the 5′ end of the SNRPN gene.

AS is a severe debilitating neurodevelopmental disorder characterized by mental retardation, speech impairment, seizures, motor dysfunction, and a high prevalence of autism. The paternal origin of the genetic material that is affected in the syndrome is important because the particular region of chromosome 15 involved is subject to parent-of-origin imprinting, meaning that for a number of genes in this region, only one copy of the gene is expressed while the other is silenced through imprinting. For the genes affected in PWS, it is the maternal copy that is usually imprinted (and thus is silenced), while the mutated paternal copy is not functional.

Phagocytes are the cells that engulf and ingest pathogens (phagocytosis), and destroy them with chemicals. Monocytes/macrophages as well as granulocytes are capable of this process. In certain conditions, either the number of phagocytes is reduced or their functional capacity is impaired.

1. Severe Congenital Neutropenia: due to ELA2 deficiency (with myelodysplasia)

2. Severe Congenital Neutropenia: due to GFI1 deficiency (with T/B lymphopenia)

3. Kostmann syndrome

4. Neutropenia with cardiac and urogenital malformations

5. Glycogen storage disease type 1b

6. Cyclic neutropenia

7. X-linked neutropenia/myelodysplasia

8. P14 deficiency

9. Leukocyte adhesion deficiency type 1

10. Leukocyte adhesion deficiency type 2

11. Leukocyte adhesion deficiency type 3

12. RAC2 deficiency (Neutrophil immunodeficiency syndrome)

13. Beta-actin deficiency

14. Localized juvenile periodontitis

15. Papillon–Lefèvre syndrome

16. Specific granule deficiency

17. Shwachman–Diamond syndrome

18. Chronic granulomatous disease: X-linked

19. Chronic granulomatous disease: autosomal ("CYBA")

20. Chronic granulomatous disease: autosomal ("NCF1")

21. Chronic granulomatous disease: autosomal ("NCF2")

22. IL-12 and IL-23 β1 chain deficiency

23. IL-12p40 deficiency

24. Interferon γ receptor 1 deficiency

25. Interferon γ receptor 2 deficiency

26. STAT1 deficiency (2 forms)

27. AD hyper-IgE

28. AR hyper-IgE

29. Pulmonary alveolar proteinosis

A survey of 10,000 American households revealed that the prevalence of diagnosed primary immunodeficiency approaches 1 in 1200. This figure does not take into account people with mild immune system defects who have not received a formal diagnosis.

Milder forms of primary immunodeficiency, such as selective immunoglobulin A deficiency, are fairly common, with random groups of people (such as otherwise healthy blood donors) having a rate of 1:600. Other disorders are distinctly more uncommon, with incidences between 1:100,000 and 1:2,000,000 being reported.

In both the classic and vascular form, the treatment is surgical. A partial styloidectomy is the preferred approach. Repair of a damaged carotid artery is essential in order to prevent further neurological complications. Regrowth of the stylohyoid process and relapse being a common occurrence is debateable.

Sertoli cell-only syndrome (a.k.a. Del Castillo syndrome and germ cell aplasia ) is a disorder characterized by male sterility without sexual abnormality. It describes a condition of the testes in which only Sertoli cells line the seminiferous tubules.

The Sertoli cell-only syndrome patients normally have normal secondary male features and have normal- or small-sized testes.

This is a rare disease with prevalence about 1 in 200,000 to 1 in 600,000. Studies showed that mutations in "CUBN" or "AMN" clustered particularly in the Scandinavian countries and the Eastern Mediterranean regions. Founder effect, higher clinical awareness to IGS, and

frequent consanguineous marriages all play a role in the higher prevalence of IGS among these populations

The cause of polymicrogyria is unclear. It is currently classified as resulting from abnormalities during late neuronal migration or early cortical organization of fetal development. Evidence for both genetic and non-genetic causes exists. Polymicrogyria appears to occur around the time of neuronal migration or early cortical development. Non-genetic causes include defects in placental oxygenation and in association with congenital infections, particularly cytomegalovirus.

An association with the gene WDR62 has been identified.