Apotemnophilia. Also known as body integrity identity disorder, apotemnophilia is characterized by the “overwhelming desire to amputate healthy parts of [the] body,” according to Medscape. Though not much is known about it, this disorder is believed to be neurological.

There are three types of genetic disorders:

• Single-gene disorders, where a mutation affects one gene. Sickle cell anemia is an example.
• Chromosomal disorders, where chromosomes (or parts of chromosomes) are missing or changed.
• Complex disorders, where there are mutations in two or more genes.

Most of the time, genetic disorders are diagnosed through a specific test, which can include examining chromosomes or DNA (the tiny proteins that make up genes), or testing the blood for certain enzymes that may be abnormal. Studying enzymes is called biochemical genetic testing.

They are not passed down from parent to child, as is the case with a hereditary disease.

• Sickle Cell Disease. Sickle cell disease is a hereditary disease caused by mutations in one of the genes that encode the hemoglobin protein.
• Cystic Fibrosis.
• Tay-Sachs.
• Hemophilia.
• Huntington’s Disease.
• Muscular Dystrophy.

Conditions That Are Hard to Diagnose

• 1 / 14. Irritable Bowel Syndrome. This condition causes pain in your belly area and changes in bathroom habits that last at least 3 months.
• 2 / 14. Celiac Disease.
• 3 / 14. Appendicitis.
• 4 / 14. Hyperthyroidism.
• 5 / 14. Hypothyroidism.
• 6 / 14. Sleep Apnea.
• 7 / 14. Lyme Disease.
• 8 / 14. Fibromyalgia.

Examples of chromosomal abnormalities include Down syndrome, Trisomy 18, Trisomy 13, Klinefelter syndrome, XYY syndrome, Turner syndrome and triple X syndrome.

A larger isodicentric chromosome 15 can result in weak muscle tone (hypotonia), mental retardation, seizures, and behavioral problems. Signs and symptoms of autism (a developmental disorder that affects communication and social interaction) have also been associated with the presence of an isodicentric chromosome 15.

One of the chromosomes that belongs to pair number 15 is abnormal in Prader-Willi syndrome. Around 70% of cases of Prader-Willi syndrome are the result of missing genetic information from the copy of chromosome 15 inherited from the father. This defect is referred to as “paternal deletion”.

For example, an extra copy of chromosome 21 causes Down syndrome (trisomy 21). Chromosomal abnormalities can also cause miscarriage, disease, or problems in growth or development. The most common type of chromosomal abnormality is known as aneuploidy, an abnormal chromosome number due to an extra or missing chromosome.

Cox regression analysis of our sample of 425 individuals with PWS and a known age at death identified quartile point estimates of 25% mortality for those 20 years of age (95% CI 18–21 years); 50% mortality for those 29 years of age (95% CI 27–32 years); and 75% mortality for those 42 years of age (95% CI 39–44 years).

Symptoms of PWS typically develop in two stages. The first symptoms often emerge during the first year of life, and others start to occur between the ages of 1 and 6 years old.

Prader-Willi syndrome (PWS) is a genetic disorder that occurs in approximately one out of every 15,000 births. PWS affects males and females with equal frequency and affects all races and ethnicities. PWS is recognized as the most common genetic cause of life-threatening childhood obesity.

The diagnosis is confirmed by a blood test. The preferred method of testing is a “methylation analysis,” which detects >99% of cases, including all of the major genetic subtypes of PWS (deletion, uniparental disomy, or imprinting mutation).

Prader-Willi syndrome has no cure. However, early diagnosis and treatment may help prevent or reduce the number of challenges that individuals with Prader-Willi syndrome may experience, and which may be more of a problem if diagnosis or treatment is delayed.

PWS is classically described as having two distinct nutritional stages: Stage 1, in which the individual exhibits poor feeding and hypotonia, often with failure to thrive (FTT); and Stage 2, which is characterized by “hyperphagia leading to obesity” [Gunay-Aygun et al., 2001; Goldstone, 2004; Butler et al., 2006].

Signs and symptoms of Prader-Willi syndrome can vary among individuals….These features may include:

• Food craving and weight gain.
• Underdeveloped sex organs.
• Poor growth and physical development.
• Cognitive impairment.
• Delayed motor development.
• Speech problems.
• Behavioral problems.
• Sleep disorders.

Prader-Willi syndrome is caused by the loss of function of genes in a particular region of chromosome 15 . People normally inherit one copy of this chromosome from each parent. Some genes are turned on (active) only on the copy that is inherited from a person’s father (the paternal copy).

Learning difficulties and a delay in development Most children with Prader-Willi syndrome have mild to moderate learning difficulties with a low IQ. This means it will take longer for a child with Prader-Willi syndrome to reach important developmental milestones.

Although specific treatments vary depending on symptoms, most children with Prader-Willi syndrome will need the following:

• Good nutrition for infants.
• Human growth hormone (HGH) treatment.
• Sex hormone treatment.
• Weight management.
• Treatment of sleep disturbances.
• Various therapies.
• Behavior management.

Noninvasive prenatal screening (NIPS) – also called noninvasive prenatal testing (NIPT) or cell–free DNA testing – is now available for Prader-Willi syndrome (PWS). Testing can be done any time after 9-10 weeks gestation because DNA from the fetus circulates in maternal blood.

Despite improvements in the genetic diagnosis of infants with Prader-Willi syndrome, diagnosis in adults appears to be lacking or is based on uncertain clinical characteristics.

Prader-Willi (PWS) and Down Syndrome (DS) are two different chromosomal disorders characterised by some common clinical features, such as obesity, muscular hypotonia, ligament laxity and mental retardation. PWS is a complex multisystemic disorder equally affecting males and females.