A genetic disorder is a genetic problem caused by one or more abnormalities in the genome, especially a condition that is present from birth (congenital). Most genetic disorders are quite rare and affect one person in every several thousands or millions.

Genetic disorders may be hereditary, passed down from the parents' genes. In other genetic disorders, defects may be caused by new mutations or changes to the DNA. In such cases, the defect will only be passed down if it occurs in the germ line. The same disease, such as some forms of cancer, may be caused by an inherited genetic condition in some people, by new mutations in other people, and mainly by environmental causes in other people. Whether, when and to what extent a person with the genetic defect or abnormality will actually suffer from the disease is almost always affected by the environmental factors and events in the person's development.

Some types of recessive gene disorders confer an advantage in certain environments when only one copy of the gene is present.

Due to the wide range of genetic disorders that are presently known, diagnosis of a genetic disorder is widely varied and dependent of the disorder. Most genetic disorders are diagnosed at birth or during early childhood, however some, such as Huntington's disease, can escape detection until the patient is well into adulthood.

The basic aspects of a genetic disorder rests on the inheritance of genetic material. With an in depth family history, it is possible to anticipate possible disorders in children which direct medical professionals to specific tests depending on the disorder and allow parents the chance to prepare for potential lifestyle changes, anticipate the possibility of stillbirth, or contemplate termination. Prenatal diagnosis can detect the presence of characteristic abnormalities in fetal development through ultrasound, or detect the presence of characteristic substances via invasive procedures which involve inserting probes or needles into the uterus such as in amniocentesis.

Upington disease, also called Perthes-like hip disease, enchondromata, ecchondromata, and familial dyschondroplasia, is an extremely rare autosomal dominant malformation disorder. It has only one published source claiming its existence in three generations of one family from South Africa.

Common symptoms of the disease are weakness and atrophy in the distal muscles of the lower limbs which progresses to the hands and arms, then to the trunk, neck and face. Respiratory impairment often follows.

The disease is characterized by Perthes-like pelvic anomalies (premature closure of the capital femoral epiphyses and widened femoral necks with flattened femoral heads), enchondromata and ecchondromata.

Gordon syndrome is an extremely rare disorder that belongs to a group of genetic disorders known as the distal arthrogryposes. These disorders typically involve stiffness and impaired mobility of certain joints of the lower arms and legs (distal extremities) including the knees, elbows, wrists, and/or ankles. These joints tend to be permanently fixed in a bent or flexed position (contractures). Gordon syndrome is characterized by the permanent fixation of several fingers in a flexed position (camptodactyly), abnormal bending inward of the foot (clubfoot or talipes), and, less frequently, incomplete closure of the roof of the mouth (cleft palate). In some cases, additional abnormalities may also be present. The range and severity of symptoms may vary from case to case. Gordon syndrome is inherited as an autosomal dominant trait.

In terms of the signs (and symptoms) of oculopharyngeal muscular dystrophy would be consistent with the following:

Though the aforementioned signs/symptoms are the most common, there have been cases though rare, where the peripheral nervous system has had involvement with significant reduction of myelinated fibers

In homozygous cases, this muscular dystrophy is severe and starts earlier in the affected individuals life.

Gordon syndrome (GS), or distal arthrogryposis type 3, is a rare, autosomal dominant disorder characterized by cleft palate and congenital contractures of the hands and feet.

Worth syndrome, also known as benign form of Worth hyperostosis corticalis generalisata with torus platinus, autosomal dominant osteosclerosis, autosomal dominant endosteal hyperostosis or Worth disease, is a rare autosomal dominant congenital disorder that is caused by a mutation in the LRP5 gene. It is characterized by increased bone density and benign bony structures on the palate.

The combination of muscular hypotonia and fixed dilated pupils in infancy is suspicious of Gillespie syndrome. Early onset partial aniridia, cerebellar ataxia, and mental retardation are hallmark of syndrome. The iris abnormality is specific and seems pathognomonic of Gillespie syndrome. The aniridia consisting of a superior coloboma and inferior iris hypoplasia, foveomacular dysplasia.

Atypical Gillespie syndrome associated with bilateral ptosis, exotropia, correctopia, iris hypoplasia, anterior capsular lens opacities, foveal hypoplasia, retinal vascular tortuosity, and retinal hypopigmentation.

Neurological signs ar nystagmus, mild craniofacial asymmetry, axial hypotonia, developmental delay, and mild mental retardation. Mariën P did not support the prevailing view of a global mental retardation as a cardinal feature of Gillespie syndrome but primarily reflect cerebellar induced neurobehavioral dysfunctions following disruption of the cerebrocerebellar anatomical circuitry that closely resembles the "cerebellar cognitive and affective syndrome" (CeCAS).

Congenital pulmonary stenosis and helix dysplasia can be associated.

The symptoms of CCD are variable, but usually involve hypotonia (decreased muscle tone) at birth, mild delay in child development (highly variable between cases), weakness of the facial muscles, and skeletal malformations such as scoliosis and hip dislocation.

Symptoms may be present at birth or may appear at any stage of life. There appears to be a growing number of people who do not become symptomatic until adulthood to middle age. While generally not progressive, again there appears to be a growing number of people who do experience a slow clinically significant progression of symptomatology. These cases may hypothetically be due to the large number of gene mutations of ryanodine receptor malfunction, and with continued research may in fact be found to be clinical variants.

The most common presentation of Milroy Disease is bilateral lower extremity lymphedema, and may also be accompanied by hydrocele.

Most infants with CMD will display some progressive muscle weakness or muscle wasting (atrophy), although there can be different degrees and symptoms of severeness of progression. The weakness is indicated as "hypotonia", or lack of muscle tone, which can make an infant seem unstable.

Children may be slow with their motor skills; such as rolling over, sitting up or walking, or may not even reach these milestones of life. Some of the more rarer forms of CMD can result in significant learning disabilities.

There are three major types of inheritance for this disease: Autosomal dominant, autosomal recessive and de novo.

- The most severe form is autosomal recessive and it also has the earliest onset. It usually involves all three muscle tissues and leads to cardiac and respiratory failure as well as intestinal obstruction.

- Autosomal Dominant inheritance shows a later onset and slower progression. It usually involves only one or two of the muscle tissues.

- De novo diseases occur when a new mutation arises in the person that was not inherited through either parent. This form has a wide range of symptoms and varies depending on the mutation made.

This autosomal dominant disorder is characterized by a number of health defects including Hirschsprung's disease, intellectual disability, epilepsy, delayed growth and motor development, congenital heart disease, genitourinary anomalies and absence of the corpus callosum. However, Hirschsprung's disease is not present in all infants with Mowat–Wilson syndrome and therefore it is not a required diagnostic criterion. Distinctive physical features include microcephaly, narrow chin, cupped ears with uplifted lobes with central depression, deep and widely set eyes, open mouth, wide nasal bridge and a shortened philtrum.

Acro–dermato–ungual–lacrimal–tooth (ADULT) syndrome is a rare genetic disease. ADULT syndrome is an autosomal dominant form of ectodermal dysplasia, a group of disorders that affects the hair, teeth, nails, sweat glands, and extremities. The syndrome arises from a mutation in the TP63 gene. This disease was previously thought to be a form of ectrodactyly–ectodermal dysplasia–cleft syndrome (EEC), but was classified as a different disease in 1993 by Propping and Zerres.

Central core disease (CCD), also known as central core myopathy, is an autosomal dominant congenital myopathy (inborn muscle disorder). It was first described by Shy and Magee in 1956. It is characterized by the appearance of the myofibril under the microscope.

Rapp–Hodgkin syndrome was formerly thought to be a unique autosomal dominant disorder due to a P63 gene mutation. However, it was recently shown to the same disease as Hay-Wells syndrome.

It was first characterized in 1968.

Steatocystoma multiplex, also known as epidermal polycystic disease and sebocystomatosis, is a benign, autosomal dominant congenital condition resulting in multiple cysts on a person's body. Steatocystoma simplex is the solitary counterpart to steatocystoma multiplex.

Clinically, three distinct patterns of palmoplantar keratoderma may be identified: diffuse, focal, and punctate.

ADULT syndrome features include ectrodactyly, syndactyly, excessive freckling, lacrimal duct anomalies, dysplastic nails, hypodontia, hypoplastic breasts and nipples, hypotrichosis, hypohidrosis, broad nasal bridge, midfacial hypoplasia, exfoliative dermatitis, and xerosis. The lack of facial clefting and ankyloblepharon are important because they exist in ectrodactyly–ectodermal dysplasia–cleft syndrome (EEC) but not in ADULT syndrome.

Congenital muscular dystrophies are autosomal recessively-inherited muscle diseases. They are a group of heterogeneous disorders characterized by muscle weakness which is present at birth and the different changes on muscle biopsy that ranges from myopathic to overtly dystrophic due to the age at which the biopsy takes place.

Milroy's disease (MD) is a familial disease characterized by lymphedema, commonly in the legs, caused by congenital abnormalities in the lymphatic system. Disruption of the normal drainage of lymph leads to fluid accumulation and hypertrophy of soft tissues. It is also known as Milroy disease, Nonne-Milroy-Meige syndrome and hereditary lymphedema.

It was named by Sir William Osler for William Milroy, a Canadian physician, who described a case in 1892, though it was first described by Rudolf Virchow in 1863.

Congenital fiber type disproportion affects skeletal muscle, typically causing weakness in the shoulders, upper arms, thighs, and hips. Skeletal muscle is made up of two kinds of fiber, type 1 and type 2. In congenital fiber type disproportion, type 1 fibers are not only smaller but often more abundant than type 2 fibers. This leads to affected individuals being able to maintain an active lifestyle, though they usually have lower levels of stamina.

Severity with this disease varies greatly, but people typically present symptoms by the age of one. Individuals do not usually worsen with time, and cases have even been reported of improvements.

Multicore myopathy, also referred to as minicore myopathy, is associated with small areas of decreased oxidative activities, resulting in areas that appear in this histology as “cores”. These appear through microscopy very similar to central core, however the cores are typically smaller in multicore myopathy. As with congenital fiber type disproportion, patients have a greater number of type 1 fibers. Overall, approximately half of diagnosed individuals report no progression of muscle weakness, while half report a very slow progression.