Prior to modern cardiovascular surgical techniques and drugs such as losartan, and metoprolol, the prognosis of those with Marfan syndrome was not good: a range of untreatable cardiovascular issues was common. Lifespan was reduced by at least a third, and many died in their teens and twenties due to cardiovascular problems. Today, cardiovascular symptoms of Marfan syndrome are still the most significant issues in diagnosis and management of the disease, but adequate prophylactic monitoring and prophylactic therapy offers something approaching a normal lifespan, and more manifestations of the disease are being discovered as more patients live longer. Women with Marfan syndrome live longer than men.

Marfan syndrome affects males and females equally, and the mutation shows no ethnic or geographical bias. Estimates indicate about 1 in 5,000 to 10,000 individuals have Marfan syndrome.

Lujan–Fryns syndrome is a rare X-linked dominant syndrome, and is therefore more common in males than females. Its prevalence within the general population has not yet been determined.

MASS syndrome a medical disorder similar to Marfan syndrome.

MASS stands for: mitral valve prolapse, aortic root diameter at upper limits of normal for body size, stretch marks of the skin, and skeletal conditions similar to Marfan syndrome. MASS Phenotype is a connective tissue disorder that is similar to Marfan syndrome. It is caused by a similar mutation in the gene called fibrillin-1 that tells the body how to make an important protein found in connective tissue. This mutation is an autosomal dominant mutation in the FBN1 gene that codes for the extracellular matrix protein fibrillin-1; defects in the fibrillin-1 protein cause malfunctioning microfibrils that result in improper stretching of ligaments, blood vessels, and skin.

Someone with MASS phenotype has a 50 percent chance of passing the gene along to each child.

People with features of MASS Phenotype need to see a doctor who knows about connective tissue disorders for an accurate diagnosis; often this will be a medical geneticist. It is very important that people with MASS Phenotype get an early and correct diagnosis so they can get the right treatment. Treatment options for MASS phenotype are largely determined on a case-by-case basis and generally address the symptoms as opposed to the actual disorder; furthermore, due to the similarities between these two disorders, individuals with MASS phenotype follow the same treatment plans as those with Marfan syndrome.

MASS stands for the Mitral valve, myopia, Aorta, Skin and Skeletal features of the disorder. MASS Phenotype affects different people in different ways.

In MASS Phenotype:

Mitral valve prolapse may be present. This is when the flaps of one of the heart’s valves (the mitral valve, which regulates blood flow on the left side of the heart) are “floppy” and don’t close tightly. Aortic root diameter may be at the upper limits of normal for body size, but unlike Marfan syndrome there is not progression to aneurysm or predisposition to dissection. Skin may show stretch marks unrelated to weight gain or loss (striae). Skeletal features, including curvature of the spine (scoliosis), chest wall deformities, and joint hypermobility, may be present. People with MASS Phenotype do not have lens dislocation but have myopia, also known as nearsightedness.

MASS syndrome and Marfan syndrome are overlapping connective tissue disorders. Both can be caused by mutations in the gene encoding a protein called fibrillin. These conditions share many of the same signs and symptoms including long limbs and fingers, chest wall abnormalities (indented chest bone or protruding chest bone), flat feet, scoliosis, mitral valve prolapse, loose or hypextensible joints, highly arched roof of the mouth, and mild dilatation of the aortic root.

Individuals with MASS syndrome do not have progressive aortic enlargement or lens dislocation, while people with Marfan syndrome do. Skin involvement in MASS syndrome is typically limited to stretch marks (striae distensae). Also, the skeletal symptoms of MASS syndrome are generally mild.

Several genetic causes of Loeys–Dietz syndrome have been identified. A "de novo" mutation in TGFB3, a ligand of the TGF ß pathway, was identified in an individual with a syndrome presenting partially overlapping symptoms with Marfan Syndrome and Loeys-Dietz Syndrome.

This syndrome, evenly spread in all ethnic groups, has a prevalence of 1-2 subjects per every 1000 males in the general population. 3.1% of infertile males have Klinefelter syndrome. The syndrome is also the main cause of male hypogonadism.

According to 2008 meta-analysis, the prevalence of the syndrome has increased over the past decades; however, this does not appear to be related to increased age of the mother at conception, as no increase was observed in the rates of other trisomies of sex chromosomes (XXX and XYY). The National Institutes of Health; however, state that older mothers might have a slightly increased risk.

Turner syndrome occurs in between one in 2000 and one in 5000 females at birth.

Approximately 99 percent of fetuses with Turner syndrome spontaneously terminate during the first trimester. Turner syndrome accounts for about 10 percent of the total number of spontaneous abortions in the United States.

As there is no known cure, Loeys–Dietz syndrome is a lifelong condition. Due to the high risk of death from aortic aneurysm rupture, patients should be followed closely to monitor aneurysm formation, which can then be corrected with interventional radiology or vascular surgery.

Previous research in laboratory mice has suggested that the angiotensin II receptor antagonist losartan, which appears to block TGF-beta activity, can slow or halt the formation of aortic aneurysms in Marfan syndrome. A large clinical trial sponsored by the National Institutes of Health is currently underway to explore the use of losartan to prevent aneurysms in Marfan syndrome patients. Both Marfan syndrome and Loeys–Dietz syndrome are associated with increased TGF-beta signaling in the vessel wall. Therefore, losartan also holds promise for the treatment of Loeys–Dietz syndrome. In those patients in which losartan is not halting the growth of the aorta, irbesartan has been shown to work and is currently also being studied and prescribed for some patients with this condition.

If an increased heart rate is present, atenolol is sometimes prescribed to reduce the heart rate to prevent any extra pressure on the tissue of the aorta. Likewise, strenuous physical activity is discouraged in patients, especially weight lifting and contact sports.

Children with XXY differ little from other children. Although they can face problems during adolescence, often emotional and behavioral, and difficulties at school, most of them can achieve full independence from their families in adulthood. Most can lead a normal, healthy life.

The results of a study carried out on 87 Australian adults with the syndrome shows that those who have had a diagnosis and appropriate treatment from a very young age had a significant benefit with respect to those who had been diagnosed in adulthood.

There is research suggesting Klinefelter syndrome substantially decreases life expectancy among affected individuals, though the evidence is not definitive. A 1985 publication identified a greater mortality mainly due to diseases of the aortic valve, development of tumors and possible subarachnoid hemorrhages, reducing life expectancy by about 5 years. Later studies have reduced this estimated reduction to an average of 2.1 years. These results are still questioned data, are not absolute, and will need further testing.

The exact role that these risk factors play in the process leading to rupture is unclear. Aortic root dilatation is thought to be due to a mesenchymal defect as pathological evidence of cystic medial necrosis has been found by several studies. The association between a similar defect and aortic dilatation is well established in such conditions such as Marfan syndrome. Also, abnormalities in other mesenchymal tissues (bone matrix and lymphatic vessels) suggests a similar primary mesenchymal defect in patients with Turner syndrome. However, no evidence suggests that patients with Turner syndrome have a significantly higher risk of aortic dilatation and dissection in absence of predisposing factors. So, the risk of aortic dissection in Turner syndrome appears to be a consequence of structural cardiovascular malformations and hemodynamic risk factors rather than a reflection of an inherent abnormality in connective tissue. The natural history of aortic root dilatation is unknown, but because of its lethal potential, this aortic abnormality needs to be carefully followed.

Wiedemann–Rautenstrauch (WR) syndrome , also known as neonatal progeroid syndrome, is an autosomal recessive progeroid syndrome.

WR was first reported by Rautenstrauch and Snigula in 1977; and the earliest reports made subsequently have been by Wiedemann in 1979, by Devos in 1981, and Rudin in 1988. There have been over 30 cases of WR.

WR is associated with abnormalities in bone maturation, and lipids and hormone metabolism. Affected individuals exhibit intrauterine and postnatal growth retardation, leading to short stature and an aged appearance from birth. They have physical abnormalities including a large head (macrocephaly), sparse hair, prominent scalp veins, inward-folded eyelid (entropion), widened anterior fontanelles, hollow cheeks (malar hypoplasia), general loss of fat tissues under the skin (lipoatrophy), delayed tooth eruption, abnormal hair pattern (hypotrichosis), beaked nose, mild to severe mental retardation and dysmorphism.

Marfan lipodystrophy syndrome (MFLS) has sometimes been confused with Wiedemann–Rautenstrauch syndrome, since the Marfanoid features are progressive and sometimes incomplete. MFLS is caused by mutations near the 3'-terminus of "FBN1" that cause a deficiency of the protein hormone asprosin and progeroid-like symptoms with reduced subcutaneous white adipose tissue.

The outlook for individuals with EDS depends on the type of EDS they have. Symptoms vary in severity, even within one sub-type, and the frequency of complications changes individually. Some people have negligible symptoms while others are severely restricted in their daily life. Extreme joint instability, chronic musculoskeletal pain, degenerative joint disease, frequent injuries, and spinal deformities may limit mobility. Severe spinal deformities may affect breathing. In the case of extreme joint instability, dislocations may result from simple tasks such as rolling over in bed or turning a doorknob. Secondary conditions such as autonomic dysfunction or cardiovascular problems, occurring in any type, can affect prognosis and quality of life. Severe mobility-related disability is seen more often in Hypermobility-type than in Classical-type or Vascular-type.

Although all types are potentially life-threatening, the majority of individuals will have a normal lifespan. However, those with blood vessel fragility have a high risk of fatal complications. Arterial rupture is the most common cause of sudden death in EDS. Spontaneous arterial rupture most often occurs in the second or third decade, but can occur at any time. The median life-expectancy in the population with Vascular EDS is 48 years.

Dennie–Marfan syndrome is a syndrome in which there is association of spastic paraplegia of the lower limbs and mental retardation in children with congenital syphilis. Both sexes are affected, and the onset of the disease can be acute or insidious, with slow progression from weakness to quadriplegia. Epilepsy, cataract, and nystagmus may be also be found.

The syndrome was described by Charles Clayton Dennie in 1929, and Antoine Marfan in 1936.

Marfanoid (or Marfanoid habitus) is a constellation of symptoms resembling those of Marfan syndrome, including long limbs, with an arm span that exceeds the height of the individual, and a crowded oral maxilla, sometimes with a high arch in the palate, arachnodactyly, and hyperlaxity.

Associated conditions include:

- Multiple endocrine neoplasia type 2B

- Homocystinuria

- Ehlers-Danlos syndrome

- Possibly Asperger syndrome

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

An individual exhibiting intellectual disability and other symptoms similar to LFS was found to have a terminal deletion of the subtelomeric region in the short arm of chromosome 5. Deletion of this area of chromosome 5 is associated with intellectual disability, psychotic behavior, autism, macrocephaly and hypernasal-like speech, as well as the disorder Cri du chat syndrome. Fryns (2006) suggests a detailed examination of chromosome 5 with FISH should be performed as part of the differential diagnosis of LFS.

Mutations in the "UPF3B" gene, also found on the X chromosome, are another cause of X-linked intellectual disability. "UPF3B" is part of the nonsense-mediated mRNA decay (NMD) complex, which performs mRNA surveillance, detecting mRNA sequences that have been erroneously truncated (shortened) by the presence of nonsense mutations. Mutations in "UPF3B" alter and prevent normal function of the NMD pathway, resulting in translation and expression of truncated mRNA sequences into malfunctioning proteins that can be associated with developmental errors and intellectual disability. Individuals from two families diagnosed with LFS and one family with FGS were found to have mutations in "UPF3B", confirming that the clinical presentations of the different mutations can overlap.

Ehlers–Danlos syndrome is an inherited disorder estimated to occur in about 1 in 5,000 births worldwide. Initially, prevalence estimates ranged from 1 in 250,000 to 1 in 500,000 people, but these estimates were soon found to be vastly inaccurate as the disorder received further study and medical professionals became more adept at accurately diagnosing EDS. In fact, many experts now believe that Ehlers–Danlos syndrome may be far more common than the currently accepted estimate due to the wide range of severities with which the disorder presents.

The prevalence of the 13 types differs dramatically. The most commonly occurring is the Hypermobility type, followed by the Classical type. The other types of Ehlers–Danlos syndrome are very rare. For example, fewer than ten infants and children with the dermatosparaxis type have been described worldwide. Some types of Ehlers–Danlos are more common in Ashkenazi Jews. For example, the chance of being a carrier for type-VIIc Ehlers–Danlos is 1 in 248 in Ashkenazi Jews, whereas the prevalence of this mutation in the general population is 1 in 2,000.

It remains unconfirmed whether composer Sergei Rachmaninoff's abnormally large reach on a piano was a result of arachnodactyly due to Marfan syndrome, as the pianist exhibited no other signs of the disease.

While not always pathological, it can present as a birth defect in multiple syndromes including:

- Catel–Manzke syndrome

- Bloom syndrome

- Coffin–Lowry syndrome

- congenital rubella

- Cri du chat syndrome

- DiGeorge's syndrome

- Ehlers-Danlos syndrome

- fetal alcohol syndrome

- Hallermann-Streiff syndrome

- Hemifacial microsomia (as part of Goldenhar syndrome)

- Juvenile idiopathic arthritis

- Marfan syndrome

- Noonan syndrome

- Pierre Robin syndrome

- Prader–Willi syndrome

- Progeria

- Russell-Silver syndrome

- Seckel syndrome

- Smith-Lemli-Opitz syndrome

- Treacher Collins syndrome

- Trisomy 13 (Patau syndrome)

- Trisomy 18 (Edwards syndrome)

- Wolf–Hirschhorn syndrome

- X0 syndrome (Turner syndrome)

Marfanoid–progeroid–lipodystrophy syndrome (MPL), also known as Marfan lipodystrophy syndrome (MFLS) or progeroid fibrillinopathy, is an extremely rare medical condition which manifests as a variety of symptoms including those usually associated with Marfan syndrome, an appearance resembling that seen in neonatal progeroid syndrome (NPS; also known as Wiedemann–Rautenstrauch syndrome), and severe partial lipodystrophy. It is a genetic condition that is caused by mutations in the "FBN1" gene, which encodes profibrillin, and affects the cleavage products of profibrillin, fibrillin-1, a fibrous structural protein, and asprosin, a glucogenic protein hormone. As of 2016, fewer than 10 cases of the condition have been reported. Lizzie Velasquez and Abby Solomon have become known publicly through the media for having the condition.

In addition to severe lipodystrophy (loss of adipose tissue), individuals with MPL show a concomitant marked loss of lean tissue mass, which also contributes to their "skinny" appearance. Based on visual inspection, it was originally thought that the lipodystrophy associated with MPL was generalized. However, it appears in fact to be partial, being confined to the face, distal extremities, and the and lateral regions of the buttocks. Normal amounts of subcutaneous fat are found in the torso over the chest and abdomen. As such, the breasts are normal in females with MPL.

Individuals with MPL have an appearance of being prematurely aged, but this is not due to actual early aging and is instead due to their paucity of subcutaneous fat. As such, MPL is not truly a form of progeria.

In 2016, it was discovered that the partial lipodystrophy associated with MPL is caused by loss of the C-terminal domain cleavage product of profibrillin and novel glucogenic protein hormone, which has been named asprosin. Due to asprosin deficiency, individuals with MPL eat less, and do not gain weight or develop symptoms of diabetes like insulin resistance. MPL patients burn less energy than normal individuals, but also consume less, and their net energy balance is moderately reduced. In contrast to MPL patients, whose asprosin is undetectable in the blood, individuals with obesity and diabetes have elevated levels of asprosin. As such, "FBN1" has been nicknamed the "thin gene", and drug development for targeted inhibition of asprosin signaling is considered to be an "unusually promising" potential therapeutic route in the treatment of obesity and diabetes.

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.

This feature can occur on its own, with no underlying health problems. However, it can also be associated with certain medical conditions. Examples include Marfan syndrome, Ehlers-Danlos syndrome, Loeys–Dietz syndrome, congenital contractural arachnodactyly, and homocystinuria.

Arachnodactyly has been linked to mutations in both fibrillin-1 and fibrillin-2 genes.

It can be detected by the naked eye as well as dental or skull X-Ray testing.

Birt-Hogg-Dubé Syndrome patients, families, and caregivers are encouraged to join the NIH Rare Lung Diseases Consortium Contact Registry. This is a privacy protected site that provides up-to-date information for individuals interested in the latest scientific news, trials, and treatments related to rare lung diseases.

Some segmental progeroid syndromes, such as Werner syndrome (WS), Bloom syndrome (BS), Rothmund-Thomson syndromes (RTS) and combined xeroderma pigmentosa-Cockayne syndrome (XP-CS), are associated with an increased risk of developing cancer in the affected individual; two exceptions are Hutchinson–Gilford progeria (HGPS) and Cockayne syndrome.