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.

Fucosidosis is an extremely rare disorder first described in 1962 in two Italian siblings who showed progressive intellectual disability and neurological deterioration. The disease itself is extremely rare (less than 100 documented cases) only affecting 1:2,000,000, with most cases being occurring in Italy, Cuba, and the southwest U.S. The disease has three different types. Type 1 and 2 are considered severe, and Type 3 being a mild disease. Symptoms are highly variable with mild cases being able to live to within the third or fourth decade. Type 1 and 2 are both linked with mental retardation. Severe cases can develop life-threatening complications early in childhood.

Because the major accumulating glycoconjugate in fucosidosis patients is the blood group H-antigen, it is intriguing to speculate, but the evidence is not clear at this time, that blood type may affect the course of the disease.

Genetic disorders may also be complex, multifactorial, or polygenic, meaning they are likely associated with the effects of multiple genes in combination with lifestyles and environmental factors. Multifactorial disorders include heart disease and diabetes. Although complex disorders often cluster in families, they do not have a clear-cut pattern of inheritance. This makes it difficult to determine a person’s risk of inheriting or passing on these disorders. Complex disorders are also difficult to study and treat, because the specific factors that cause most of these disorders have not yet been identified. Studies which aim to identify the cause of complex disorders can use several methodological approaches to determine genotype-phenotype associations. One method, the genotype-first approach, starts by identifying genetic variants within patients and then determining the associated clinical manifestations. This is opposed to the more traditional phenotype-first approach, and may identify causal factors that have previously been obscured by clinical heterogeneity, penetrance, and expressivity.

On a pedigree, polygenic diseases do tend to "run in families", but the inheritance does not fit simple patterns as with Mendelian diseases. But this does not mean that the genes cannot eventually be located and studied. There is also a strong environmental component to many of them (e.g., blood pressure).

- asthma

- autoimmune diseases such as multiple sclerosis

- cancers

- ciliopathies

- cleft palate

- diabetes

- heart disease

- hypertension

- inflammatory bowel disease

- intellectual disability

- mood disorder

- obesity

- refractive error

- infertility

The life expectancy for individuals with Salla disease is between the ages of 50 and 60.

Acheiropodia (ACHP), also known as Horn-Kolb Syndrome, Acheiropody and Aleijadinhos (Brazilian type), is an autosomal recessive disorder that results in hemimelia, a lack of formation of the distal extremities.

This is a congenital defect which consists of bilateral amputations of the distal upper and lower extremities, as well as aplasia of the hands and feet. It was first discovered and is prevalent almost exclusively in Brazil.

There have been 30 cases of Marden-Walker Syndrome reported since 1966. The first case of this was in 1966 a female infant was diagnosed with blepharophimosis, joint contractures, arachnodactyly and growth development delay. She ended up passing at 3 months due to pneumonia.

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.

Autosomal recessive cerebellar ataxia type 1 (ARCA1) is a condition characterized by progressive problems with movement. Signs and symptoms of the disorder first appear in early to mid-adulthood. People with this condition initially experience impaired speech (dysarthria), problems with coordination and balance (ataxia), or both. They may also have difficulty with movements that involve judging distance or scale (dysmetria). Other features of ARCA1 include abnormal eye movements (nystagmus) and problems following the movements of objects with their eyes. The movement problems are slowly progressive, often resulting in the need for a cane, walker, or wheelchair.

Fukuyama congenital muscular dystrophy has a poor prognosis. Most children with FCMD reach a maximum mobility at sitting upright and sliding. Due to the compounded effects of continually worsening heart problems, impaired mental development, problems swallowing and additional complications, children with FCMD rarely live through adolescence, the disorder proves fatal by age 20.

HDL1 is an unusual, autosomal dominant familial prion disease. Only described in one family, it is caused by an eight-octapeptide repeat insertion in the "PRNP" gene. More broadly, inherited prion diseases in general can mimic HD.

Vici syndrome is inherited in an autosomal recessive manner. This means the defective gene responsible for the disorder is located on an autosome, and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder.

The hypothesis of autosomal recessive inheritance of Vici syndrome was strengthened in 2002 with the clinical description of two new cases, one brother and one sister, by Chiyonobu et al.

This condition is a consequence of mutations in the PEX7 gene, GNPAT gene (which is located on chromosome 1) and AGPS gene, the condition is acquired in a autosomal recessive manner.

Canine fucosidosis is found in the English Springer Spaniel.

Typically affecting dogs between 18 months and four years, symptoms include:

- Loss of learned behavior

- Change in temperament

- Blindness

- Loss of balance

- Deafness

- Weight loss

- From the onset, disease progress is quick and fatal.

Just like the human version, canine fucosidosis is a recessive disorder and two copies of the gene must be present, one from each parent, in order to show symptoms of the disease.

Marden–Walker syndrome (MWS) is a rare autosomal recessive congenital disorder. It is characterized by blepharophimosis, microcephaly, micrognathia, multiple joint contractures, arachnodactyly, camptodactyly, kyphoscoliosis, and delayed motor development and is often associated with cystic dysplastic kidneys, dextrocardia, Dandy-Walker malformation, and agenesis of corpus callosum".

Vici syndrome is caused by mutations in the gene EPG5 (OMIM # 615068), which encodes an important regulator of the autophagy pathway, the ectopic P-granules autophagy protein 5, involved in the formation of lysosomes.

EPG5 is the human homolog of the C.elegans epg5 gene. The gene EPG5 has been cloned for the first time by Nagase et al. by sequencing clones obtained from a size-fractionated fetal brain cDNA library, and was initially named KIAA1632.

The EPG5 human gene is located on chromosome 18q12.3, has a length of 119,67Kb (NC_000018.10), consists of 44 exons and is transcriptionally driven from the centromere toward the telomere. The messenger RNA (mRNA) is 12633bp long (NM_020964.2) and contains a CDS of 7740 bp translated into a protein sequence of 2579 amino acids (NP_066015.2) with a molecular weight of 280kDa, presumed. The protein EPG5 is expressed primarily in the central nervous system (CNS), skeletal muscle, heart, thymus, cells of the immune system, lungs and kidneys.

Mutations in the EPG5 gene interfere with the autophagy. This appears to be due to a block in the autophagosome-lysosome fusion mechanism.

The Huntington's disease-like syndromes (often abbreviated as HD-like or "HDL" syndromes) are a family of inherited neurodegenerative diseases that closely resemble Huntington's disease (HD) in that they typically produce a combination of chorea, cognitive decline or dementia and behavioural or psychiatric problems.

MDM is most common on the Dalmatian island of Mljet (or "Meleda"), thought to be because of a founder effect. It is of autosomal recessive inheritance. It may be caused by a mutation on the "SLURP1" gene, located on chromosome 8.

EEM syndrome (or Ectodermal dysplasia, Ectrodactyly and Macular dystrophy syndrome) is an autosomal recessive congenital malformation disorder affecting tissues associated with the ectoderm (skin, hair, nails, teeth), and also the hands, feet and eyes.

Fukuyama congenital muscular dystrophy (FCMD) is a rare, autosomal recessive form of muscular dystrophy (weakness and breakdown of muscular tissue) mainly described in Japan but also identified in Turkish and Ashkenazi Jewish patients, fifteen cases were first described on 1960 by Fukuyama.

FCMD mainly affects the brain, eyes, and muscles, in particular, the disorder affects development of the skeletal muscles leading to weakness and deformed appearances, and brain development is blunted affecting cognitive functioning as well as social skills. In 1995, the disorder was linked to mutations in a gene coding for the protein fukutin (the "FCMD" gene). Fukuyama congenital muscular dystrophy is the second most prevalent form of muscular dystrophy in Japan. One out of every 90 people in Japan is a heterozygous carrier.

Salla disease (SD), also called sialic acid storage disease or Finnish type sialuria, is an autosomal recessive lysosomal storage disease characterized by early physical impairment and mental retardation. It was first described in 1979, after Salla, a municipality in Finnish Lapland. Salla disease is one of 40 Finnish heritage diseases and affects approximately 130 individuals, mainly from Finland and Sweden.

The mechanism of rhizomelic chondrodysplasia punctata in the case of "type 1" of this condition one finds that peroxisome objective is PEX7, in peroxisome assembly.There are 3 pathways that "count on" PEX7 and are:

Dejerine–Sottas neuropathy is caused by a genetic defect either in the proteins found in axons or the proteins found in myelin. Specifically, it has been associated with mutations in "MPZ", "PMP22", "PRX", and "EGR2" genes. The disorder is inherited in an autosomal dominant or autosomal recessive manner.

Mäkelä-Bengs et al. (1997,1998) performed a genome-wide screening and linkage analysis and assigned the LCCS locus to a defined region of 9q34.

The GM1 gangliosidoses (or GM1 gangliosidos"i"s) are caused by a deficiency of beta-galactosidase, with resulting abnormal storage of acidic lipid materials in cells of the central and peripheral nervous systems, but particularly in the nerve cells.

GM1 Gangliosidoses are inherited, autosomal recessive sphingolipidoses, resulting from marked deficiency of Acid Beta Galactosidase.

Haemochromatosis type 3 is a type of Iron overload disorder associated with deficiencies in transferrin receptor 2. It exhibits an autosomal recessive inheritance pattern.