The recurrence of DOOR in siblings and the finding of DOOR syndrome in a few families with consanguinity suggest that the condition is an autosomal recessive genetic condition. Mutations in TBC1D24 have been identified in 9 families.

DOOR (deafness, onychdystrophy, osteodystrophy, and mental retardation) syndrome is a genetic disease which is inherited in an autosomal recessive fashion. DOOR syndrome is characterized by mental retardation, sensorineural deafness, abnormal nails and phalanges of the hands and feet, and variable seizures. A similar deafness-onychodystrophy syndrome is transmitted as an autosomal dominant trait and has no mental retardation. Some authors have proposed that it may be the same as Eronen Syndrome, but since both disorders are extremely rare it is hard to make a determination.

This disorder is present at birth, however, it may not be understood until several years after birth. Acrodysostosis affects males and females in almost similar numbers. It is difficult to determine the frequency of acrodysostosis in the population as many cases of this disorder cannot be diagnosed properly.

This disorder is caused by an abnormality of the TBCE gene, the locus for which is on Chromosome 1q42.3. The locus is a 230 kb region of gene with identified deletions and mutations in affected individuals. There are rare cases of the disorder not being due to a TBCE gene abnormality.

Marinesco–Sjögren syndrome (MSS), sometimes spelled Marinescu–Sjögren syndrome, is a rare autosomal recessive disorder.

In most cases, between the age of 2 and 4 oculomotor signals are present. Between the age of 2 and 8, telangiectasias appears. Usually by the age of 10 the child needs a wheel chair. Individuals with autosomal recessive cerebellum ataxia usually survive till their 20s; in some cases individuals have survived till their 40s or 50s.

The cause of this condition is apparently due to mutation in the UBE3B gene and is inherited via autosomal recessive manner. This gene is located at molecular location- base pairs 109,477,410 to 109,543,628 and position 24.11 on chromosome 12.

Young–Simpson syndrome (YSS) is a rare congenital disorder with symptoms including hypothyroidism, heart defects, facial dysmorphism, cryptorchidism in males, hypotonia, mental retardation and postnatal growth retardation.

Other symptoms include transient hypothyroidism, macular degeneration and torticollis. The condition was discovered in 1987 and the name arose from the individuals who first reported the syndrome. An individual with

YSS has been identified with having symptoms to a similar syndrome known as Ohdo Blepharophimosis syndrome, showing that it is quite difficult to diagnose the correct condition based on the symptoms present. Some doctors therefore consider these syndromes to be the same.

The mode of inheritance has had mixed findings based on studies undertaken. One study showed that the parents of an individual with YSS are unrelated and phenotypically normal, indicating a sporadic mutation, thus making it difficult to base the cause of the condition on genetic makeup alone. However, another study was done of an individual with YSS who had first cousins as parents, giving the possibility of autosomal recessive inheritance.

VLDLR-associated cerebellar hypoplasia (VLDLRCH; alternative names: dysequilibrium syndrome, DES; nonprogressive cerebellar disorder with mental retardation) is a rare autosomal recessive condition caused by a disruption of the VLDLR gene. First described as a form of cerebral palsy in the 1970s, it is associated with parental consanguinity and is found in secluded communities, with a number of cases described in Hutterite families.

Hennekam syndrome also known as intestinal lymphagiectasia–lymphedema–mental retardation syndrome, is an autosomal recessive disorder consisting of intestinal lymphangiectasia, facial anomalies, peripheral lymphedema, and mild to moderate levels of growth and intellectual disability.

It is also known as "lymphedema-lymphangiectasia-mental retardation syndrome".

In a subset of patients it is associated with CCBE1 according research published by its namesake, Raoul Hennekam. Other causal mutations were found in the FAT4 gene. Previously, mutations in the FAT4 gene had been only associated with van Maldergem syndrome. The molecular mechanism of the lymphedema phenotype in CCBE1-associated cases was identified as a diminished ability of the mutated CCBE1 to accelerate and focus the activation of the primary lymphangiogenic growth factor VEGF-C.

Worldwide, it has been documented in 110 persons, 85 of them Finnish. It is a recessive genetic disease. Many people with Mulibrey nanism have parents who are closely related, consanguine. Signs and symptoms are variable, siblings who suffer this disease sometimes do not share the same symptoms.

The mechanism (or pathogenesis) of Kaufman oculocerebrofacial syndrome appears to begin due to a mutation in the E3 ubiquitin protein ligase. (UBE3B).

One finds that the normal mechanism of UBE3B gene is important in the ubiquitin-proteasome system.The aforementioned system helps to remove proteins that have degraded. However, when not working properly due to the mutation in the UBE3B gene(at least 15 mutations) results in an unstable UBE3B protein which has a negative effect on the ubiquitin-proteasome system.

X-linked intellectual disability (previously known as X-linked mental retardation) refers to forms of intellectual disability which are specifically associated with X-linked recessive inheritance.

As with most X-linked disorders, males are more heavily affected than females. Females with one affected X chromosome and one normal X chromosome tend to have milder symptoms.

Unlike many other types of intellectual disability, the genetics of these conditions are relatively well understood. It has been estimated there are ~200 genes involved in this syndrome; of these ~100 have been identified.

X-linked intellectual disability accounts for ~16% of all cases of intellectual disability in males.

Genitopatellar Syndrome is an autosomal dominant inheritance where the mutation in the KAT6B causes the syndrome. The KAT6B gene is responsible for making an enzyme called histone acetyltransferase which functions in regulating and making of histone which are proteins that attach to DNA and give the chromosomes their shape. The function of histone acetyltransferase produced from KAT6B is unknown but it is considered as a regulator of early developments. There is little known about how the mutation in the KAT6B causes the syndrome but researchers suspects that the mutations occur near the end of the KAT6B gene and causes it to produce shortened acetyltransferase enzyme. The shortened enzyme alters the regulation of other genes. On the other hand, the mutation of KAT6B leading to the specific features of genitopatellar syndrome is still not surely proven.

Several X-linked syndromes include intellectual disability as part of the presentation. These include:

- Coffin–Lowry syndrome

- MASA syndrome

- MECP2 duplication syndrome

- X-linked alpha thalassemia mental retardation syndrome

- mental retardation and microcephaly with pontine and cerebellar hypoplasia

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

Acrodysostosis also known as Arkless-Graham syndrome or Maroteaux-Malamut syndrome is a rare congenital malformation syndrome which involves shortening of the interphalangeal joints of the hands and feet, intellectual disability in approximately 90% of affected children, and peculiar facies. Other common abnormalities include short head (as measured front to back), small broad upturned nose with flat nasal bridge, protruding jaw, increased bone age, intrauterine growth retardation, juvenile arthritis and short stature. Further abnormalities of the skin, genitals, teeth, and skeleton may occur.

Most reported cases have been sporadic, but it has been suggested that the condition might be genetically related i.e. in an autosomal dominant mode of transmission. Both males and females are affected. The disorder has been associated with the older age of parents at the time of conception.

A PRKAR1A mutation has been identified in acrodysostosis with hormone resistance.

Gillespie syndrome, also called aniridia, cerebellar ataxia and mental deficiency. is a rare genetic disorder. The disorder is characterized by partial aniridia (meaning that part of the iris is missing), ataxia (motor and coordination problems), and, in most cases, intellectual disability. It is heterogeneous, inherited in either an autosomal dominant or autosomal recessive manner. Gillespie syndrome was first described by American ophthalmologist Fredrick Gillespie in 1965.

Because MOMO is such a rare disorder, very few studies have been conducted into its causes. Current research suggests that it is linked to a de novo (new) autosomal dominant mutation.

Sanjad-Sakati syndrome is a rare autosomal recessive genetic condition seen in offspring of Middle Eastern origin. It was first described in Saudi Arabia, but has been seen in Qatari, Kuwaiti, Omani and other children from the Middle East as well as elsewhere. The condition is caused by mutations or deletions in the TBCE gene of Chromosome No.1.

The condition is characterised by a triad of growth and mental retardation, hypoparathyroidism and dysmorphism.

Cohen syndrome (also known as Pepper syndrome or Cervenka syndrome, named after Michael Cohen, William Pepper and Jaroslav Cervenka, who researched the illness) is a genetic disorder.

Unfortunately, there is not one specific treatment option that can rid a person of this syndrome. However, there are many routes one can take to make living with this disease a lot easier. For example, there are many treatment programs that doctors can specialize for patients and their needs. Meeting with a doctor is very crucial and these specializations can be very useful. Also, one can seek help from pediatricians, EENT doctors, audiologists, and orthopedists. Brace fittings, hearing aids, and physical therapy can also be pushed by one's doctor, so that a patient can live normally. Additionally, anticonvulsant drugs can be used to stop seizures.

There is no known prevention of spinocerebellar ataxia. Those who are believed to be at risk can have genetic sequencing of known SCA loci performed to confirm inheritance of the disorder.

Treatment for MSS is symptomatic and supportive including physical and occupational therapy, speech therapy, and special education. Cataracts must be removed when vision is impaired, generally in the first decade of life. Hormone replacement therapy is needed if hypogonadism is present.

Oculofaciocardiodental syndrome is a rare X linked genetic disorder.