: 12/09/16
1. Angelman Syndrome
Angelman syndrome (AS) is a neurodevelopmental disorder characterized by severe
intellectual and developmental disability, sleep disturbance, seizures, jerky movements
(especially hand-flapping), frequent laughter or smiling, and usually a happy demeanor. AS is a
classic example of genomic imprinting in that it is caused by deletion or inactivation of genes on
the maternally inherited chromosome 15 while the paternal copy, which may be of normal
sequence, is imprinted and therefore silenced. AS is named after a British pediatrician, Harry
Angelman, who first described the syndrome in 1965. An older, alternative term for AS, "happy
puppet syndrome", is generally considered pejorative and stigmatizing so it is no longer the
accepted term. People with AS are sometimes referred to as "angels", both because of the
syndrome's name and because of their youthful, happy appearance.
2. Canavan Disease
Canavan disease is a rare inherited disorder that damages the ability of nerve cells (neurons)
in the brain to send and receive messages. This disease is one of a group of genetic disorders
called leukodystrophies. Leukodystrophies disrupt the growth or maintenance of the myelin
sheath, which is the covering that protects nerves and promotes the efficient transmission of
nerve impulses. Neonatal/infantile Canavan disease is the most common and most severe form of
the condition. Affected infants appear normal for the first few months of life, but by age 3 to 5
months, problems with development become noticeable. These infants usually do not develop
motor skills such as turning over, controlling head movement, and sitting without support. The
life expectancy for people with Canavan disease varies. Most people with the neonatal/infantile
form live only into childhood, although some survive into adolescence or beyond. People with
the mild/juvenile form do not appear to have a shortened lifespan.
3. Down Syndrome
Down syndrome is a chromosomal condition that is associated with intellectual disability, a
characteristic facial appearance, and weak muscle tone (hypotonia) in infancy. All affected
individuals experience cognitive delays, but the intellectual disability is usually mild to
moderate. People with Down syndrome may have a variety of birth defects. About half of all
affected children are born with a heart defect. Digestive abnormalities, such as a blockage of the
intestine, are less common. These include gastroesophageal reflux, which is a backflow of acidic
stomach contents into the esophagus, and celiac disease, which is an intolerance of a wheat
protein called gluten. About 15 percent of people with Down syndrome have an underactive
thyroid gland (hypothyroidism).They also have an increased risk of hearing and vision problems.
4. Turner Syndrome
Turner syndrome, a condition that affects only girls and women, results when a sex
chromosome (the X chromosome) is missing or partially missing. Turner syndrome can cause a
variety of medical and developmental problems, including short height, failure to start puberty,
infertility, heart defects, certain learning disabilities and social adjustment problems. This
syndrome may be diagnosed before birth (prenatal), during infancy or in early childhood.
Occasionally the diagnosis is delayed until the teen or young adult years in those who have mild
signs and symptoms of Turner syndrome. Nearly all girls and women with Turner syndrome
need ongoing medical care from a variety of specialists. Regular checkups and appropriate care
can help most girls and women lead relatively healthy, independent lives.
5. Klinefelter Syndrome
Klinefelter syndrome (KS) also known as 47,XXY or XXY, is the set of symptoms that result
from two or more X chromosomes in males. The primary feature is sterility. Often symptoms
may be subtle and many people do not realize they are affected. Sometimes symptoms are more
prominent and may include weaker muscles, greater height, poor coordination, less body hair,
smaller genitals, breast growth, and less interest in sex. Often it is only at puberty that these
symptoms are noticed. Intelligence is usually normal; however, reading difficulties and problems
with speech are more common. Symptoms are typically more severe if three or more X
chromosomes are present. It usually occurs randomly. An older mother might increase the risk
slightly. The condition is not inherited from one's parents. The underlying mechanisms involve at
least one extra X chromosome in addition to a Y chromosome such that there is a total of 47 or
more chromosomes rather than usual 46. KS is diagnosed by the genetic test known as a
6. Cystic Fibrosis
Cystic fibrosis is an inherited disorder that causes severe damage to the lungs, digestive
system and other organs in the body. Cystic fibrosis affects the cells that produce mucus, sweat
and digestive juices. These secreted fluids are normally thin and slippery. But in people with
cystic fibrosis, a defective gene causes the secretions to become sticky and thick. Instead of
acting as a lubricant, the secretions plug up tubes, ducts and passageways, especially in the lungs
and pancreas.
7. Haemophilia
Haemophilia, also spelled hemophilia, is a mostly inherited genetic disorder that impairs the
body's ability to make blood clots, a process needed to stop bleeding. This results in people
bleeding longer after an injury, easy bruising, and an increased risk of bleeding inside joints or
the brain. Those with mild disease may only have symptoms after an accident or during surgery.
Bleeding into a joint can result in permanent damage while bleeding in the brain can result in
long term headaches, seizures, or a decreased level of consciousness. There are two main types
of haemophilia: haemophilia A, which occurs due to not enough clotting factor VIII, and
haemophilia B, which occurs due to not enough clotting factor IX. They are typically inherited
from one's parents through an X chromosome with a nonfunctional gene. Acquired haemophilia
is associated with cancers, autoimmune disorders, and pregnancy. Diagnosis is by testing the
blood for its ability to clot and its levels of clotting factors.
8. Joubert Syndrome
Joubert syndrome is one of the many genetic syndromes associated with syndromic retinitis
pigmentosa. The syndrome was first identified in 1969 by pioneering pediatric neurologist Marie
Joubert in Montreal, Canada, while working at the Montreal Neurological Institute and McGill
University.[ The disorder is characterized by absence or underdevelopment of the cerebellar
vermis and a malformed brain stem (molar tooth sign). The most common features include ataxia
(lack of muscle control), hyperpnea (abnormal breathing patterns), sleep apnea, abnormal eye
and tongue movements, and hypotonia. Other malformations such as extra fingers and toes, cleft
lip or palate, tongue abnormalities, and seizures may also occur. Developmental, including
cognitive, is always present to some degree. Usually the mental retardation will be present.
9. Phenylketonuria
Phenylketonuria (commonly known as PKU) is an inherited disorder that increases the levels
of a substance called phenylalanine in the blood. Phenylalanine is a building block of proteins
(an amino acid) that is obtained through the diet. It is found in all proteins and in some artificial
sweeteners. If PKU is not treated, phenylalanine can build up to harmful levels in the body,
causing intellectual disability and other serious health problems. The signs and symptoms of
PKU vary from mild to severe. The most severe form of this disorder is known as classic PKU.
Infants with classic PKU appear normal until they are a few months old. Without treatment,
these children develop permanent intellectual disability. Untreated individuals may have a musty
or mouse-like odor as a side effect of excess phenylalanine in the body. Children with classic
PKU tend to have lighter skin and hair than unaffected family members.
10. Duchenne Muscular Dystrophy
Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy. The symptom
of muscle weakness usually begins around the age of four in boys and worsens quickly.
Typically muscle loss occurs first in the upper legs and pelvis followed by those of the upper
arms. This can result in trouble standing-up. Most are unable to walk by the age of twelve.
Affected muscles may look larger due to increased fat content. Some may have intellectual
disability. Females with a single copy of the defective gene may show mild symptoms. The
disorder is X-linked recessive. About two thirds of cases are inherited from a person's parents
while one third of cases are due to a new mutation. It is caused by a mutation in the gene for the
protein dystrophin. Those affected also have a high level of creatine kinase in their blood. There
is no cure for muscular dystrophy. Physical therapy, braces, and corrective surgery may help
with some symptoms.
11. Sickle Cell Disease
The term sickle cell disease (SCD) describes a group of inherited red blood cell disorders.
People with SCD have abnormal hemoglobin, called hemoglobin S or sickle hemoglobin, in their
red blood cells. Hemoglobin is a protein in red blood cells that carries oxygen throughout the
body. “Inherited” means that the disease is passed by genes from parents to their children. SCD
is not contagious. A person cannot catch it, like a cold or infection, from someone else. People
who have SCD inherit two abnormal hemoglobin genes, one from each parent. In all forms of
SCD, at least one of the two abnormal genes causes a person’s body to make hemoglobin S.
When a person has two hemoglobin S genes, Hemoglobin SS, the disease is called sickle cell
anemia. This is the most common and often most severe kind of SCD.
12. Neurofibromatosis
Neurofibromatosis (NF) is a group of three conditions in which tumors grow in the nervous
system. The three types are neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and
schwannomatosis. In NF1 symptoms include light brown spots on the skin, freckles in the armpit
and groin, small bumps within nerves, and scoliosis. In NF2 there may be hearing loss, cataracts
at a young age, balance problems, flesh colored skin flaps, and muscle wasting. The tumors are
generally non-cancerous. The cause is a genetic mutation in certain genes. In half of cases these
are inherited from a person's parents while in the rest they occur during early development. The
tumors involve supporting cells in the nervous system rather than the neurons. In NF1 the tumors
are neurofibromas (tumors of the peripheral nerves) while in NF2 and schwannomatosis tumors
of Schwann cells are more common. There is no known prevention or cure.
13. Tay-Sachs Disease
Tay-Sachs disease is a rare inherited disorder that progressively destroys nerve cells
(neurons) in the brain and spinal cord. The most common form of Tay-Sachs disease becomes
apparent in infancy. Infants with this disorder typically appear normal until the age of 3 to 6
months, when their development slows and muscles used for movement weaken. Affected
infants lose motor skills such as turning over, sitting, and crawling. They also develop an
exaggerated startle reaction to loud noises. As the disease progresses, children with Tay-Sachs
disease experience seizures, vision and hearing loss, intellectual disability, and paralysis. An eye
abnormality called a cherry-red spot, which can be identified with an eye examination, is
characteristic of this disorder. Children with this severe infantile form of Tay-Sachs disease
usually live only into early childhood.
14. Spinal Muscular Atrophy
Spinal muscular atrophy is a genetic disorder that affects the control of muscle movement. It
is caused by a loss of specialized nerve cells, called motor neurons, in the spinal cord and the
part of the brain that is connected to the spinal cord (the brainstem). The loss of motor neurons
leads to weakness and wasting (atrophy) of muscles used for activities such as crawling, walking,
sitting up, and controlling head movement. In severe cases of spinal muscular atrophy, the
muscles used for breathing and swallowing are affected. There are many types of spinal
muscular atrophy distinguished by the pattern of features, severity of muscle weakness, and age
when the muscle problems begin.
15. Triple X Syndrome
Triple X syndrome, also called trisomy X or 47,XXX, is characterized by the presence of an
additional X chromosome in each of a female's cells. Although females with this condition may
be taller than average, this chromosomal change typically causes no unusual physical features.
Most females with triple X syndrome have normal sexual development and are able to conceive
children. It is associated with an increased risk of learning disabilities and delayed development
of speech and language skills. Delayed development of motor skills (such as sitting and
walking), weak muscle tone (hypotonia), and behavioral and emotional difficulties are also
possible, but these characteristics vary widely among affected girls and women. Seizures or
kidney abnormalities occur in about 10 percent of affected females.
16. Fabry Disease
Fabry disease is an inherited disorder that results from the buildup of a particular type of fat,
called globotriaosylceramide, in the body's cells. Beginning in childhood, this buildup causes
signs and symptoms that affect many parts of the body. Characteristic features of Fabry disease
include episodes of pain, particularly in the hands and feet (acroparesthesias); clusters of small,
dark red spots on the skin called angiokeratomas; a decreased ability to sweat (hypohidrosis);
cloudiness of the front part of the eye (corneal opacity); problems with the gastrointestinal
system; ringing in the ears (tinnitus); and hearing loss. Fabry disease also involves potentially
life-threatening complications such as progressive kidney damage, heart attack, and stroke. Some
affected individuals have milder forms of the disorder that appear later in life and affect only the
heart or kidneys.
17. Galactosemia
Galactosemia is a disorder that affects how the body processes a simple sugar called
galactose. A small amount of galactose is present in many foods. The signs and symptoms of
galactosemia result from an inability to use galactose to produce energy. Researchers have
identified several types of galactosemia. These conditions are each caused by mutations in a
particular gene and affect different enzymes involved in breaking down galactose. Classic
galactosemia, also known as type I, is the most common and most severe form of the condition.
If infants with classic galactosemia are not treated promptly with a low-galactose diet, lifethreatening complications appear within a few days after birth. Galactosemia type II causes
fewer medical problems than the classic type. Affected infants develop cataracts but otherwise
experience few long-term complications.
18. Harlequin-type Ichthyosis
Harlequin-type ichthyosis is a very rare severe genetic disease, which causes thickening of
the skin. At birth, the child’s whole body is encased in an 'armor' of thick white plates of skin,
separated with deep cracks. In addition, the eyes, ears, penis, and limbs may be abnormally
contracted. Because of resultant cracked skin in locations where normal skin would fold, it is
easily pregnable by bacteria and other contaminants, which can result in serious risk of fatal
infection. It is an autosomal recessive congenital ichthyosis, which is a group of nonsyndromic
disorders of keratinization. It is associated with a mutation in the gene for the protein ABCA12.
The disease can be diagnosed in the uterus by way of fetal skin biopsy or by analysis of amniotic
fluid cells obtained by amniocentesis. Common features of the disease can be recognized through
ultrasound, and follow up with 3D ultrasound to diagnose the condition.
19. Huntington's Disease
Huntington's disease (HD), also known as Huntington's chorea, is an inherited disorder that
results in death of brain cells. The earliest symptoms are often subtle problems with mood or
mental abilities. A general lack of coordination and an unsteady gait often follow. As the disease
advances, uncoordinated, jerky body movements become more apparent. Physical abilities
gradually worsen until coordinated movement becomes difficult and the person is unable to talk.
Mental abilities generally decline into dementia. Symptoms usually begin between 30 and 50
years of age, but can start at any age. The disease may develop earlier in life in each successive
generation. HD is typically inherited from a person's parents with 10% of cases due to a new
mutation. The disease is caused by an autosomal dominant mutation in either of an individual's
two copies of a gene called Huntingtin. There is no cure for HD.
20. Polycystic Kidney Disease
Polycystic kidney disease is a genetic disorder that causes numerous cysts to grow in the
kidneys. A kidney cyst is an abnormal sac filled with fluid. PKD cysts can greatly enlarge the
kidneys while replacing much of their normal structure, resulting in chronic kidney disease
(CKD), which causes reduced kidney function over time. CKD may lead to kidney failure,
described as end-stage kidney disease or ESRD when treated with a kidney transplant or bloodfiltering treatments called dialysis. A gene mutation, or defect, causes polycystic kidney disease.
Genes provide instructions for making proteins in the body. A gene mutation is a permanent
change in the deoxyribonucleic acid (DNA) sequence that makes up a gene. In most cases of
PKD, a person inherits the gene mutation, meaning a parent passes it on in his or her genes.
21. Wilson’s Disease
Wilson disease is a genetic disease that prevents the body from removing extra copper. The
body needs a small amount of copper from food to stay healthy; however, too much copper is
poisonous. In Wilson disease, the liver does not filter copper correctly and copper builds up in
the liver, brain, eyes, and other organs. Over time, high copper levels can cause life-threatening
organ damage. Wilson disease is caused by an inherited autosomal recessive mutation, or
change, in the ATP7B gene. In an autosomal recessive disease, the child has to inherit the gene
mutation from both parents to have an increased likelihood for the disease. The chance of a child
inheriting autosomal recessive mutations from both parents with a gene mutation is 25 percent,
or one in four.
22. FG Syndrome
FG syndrome is a genetic condition that affects many parts of the body and occurs almost
exclusively in males. "FG" represents the surname initials of the first family diagnosed with the
disorder. FG syndrome affects intelligence and behavior. Almost everyone with the condition has
intellectual disability, which ranges from mild to severe. Compared to people with other forms of
intellectual disability, their socialization and daily living skills are strong, while verbal
communication and language skills tend to be weaker. The physical features of FG
syndrome include weak muscle tone (hypotonia), broad thumbs, and wide first (big) toes.
Abnormalities of the tissue connecting the left and right halves of the brain (the corpus callosum)
are also common. People with FG syndrome also tend to have a distinctive facial appearance
including small, underdeveloped ears; a tall, prominent forehead; and outside corners of the eyes
that point downward (down-slanting palpebral fissures).
23. Campomelic Dysplasia
Campomelic dysplasia (CMD) is a rare genetic disorder characterized by bowing of the long
bones and many other skeletal and extraskeletal features. It is frequently lethal in
the neonatal period due to respiratory insufficiency, but the severity of the disease is variable,
and some patients survive into adulthood. The name is derived from the Greek
roots campo (or campto), meaning bent, and melia, meaning limb. An unusual aspect of the
disease is that up to two-thirds of affected 46,XY genotypic males display a range of Disorders
of Sexual Development (DSD) and genital ambiguities or may even develop as
normal phenotypic females as in complete 46 XY sex reversal. An atypical form of the disease
with absence of bowed limbs is called, prosaically, acampomelic campomelic dysplasia (ACD)
and is found in about 10% of patients, particularly those surviving the neonatal period. CMD is
caused by chromosomal abnormalities, generally spontaneously arising or de novo mutations, in
or around the gene SOX9 on the long arm of chromosome 17, specifically at position 17q24.
24. Cowden Syndrome
Cowden syndrome is a disorder characterized by multiple noncancerous, tumor-like growths
called hamartomas and an increased risk of developing certain cancers. Cowden syndrome is
associated with an increased risk of developing several types of cancer, particularly cancers of
the breast, a gland in the lower neck called the thyroid, and the lining of the uterus
(the endometrium). Other cancers that have been identified in people with Cowden
syndrome include colorectal cancer, kidney cancer, and a form of skin cancer called melanoma.
25. Gaucher Disease
Gaucher disease is an inherited disorder that affects many of the body's organs and tissues.
The signs and symptoms of this condition vary widely among affected individuals. Researchers
have described several types of Gaucher disease based on their characteristic features. Type
1 Gaucher disease is the most common form of this condition. Type 1 is also called nonneuronopathic Gaucher disease because the brain and spinal cord (the central nervous system)
are usually not affected. Major signs and symptoms include enlargement of the liver and spleen
(hepatosplenomegaly), anemia, easy bruising caused by a decrease in blood platelets
(thrombocytopenia), lung disease, and bone abnormalities such as bone pain, fractures, and
arthritis. Types 2 and 3 Gaucher disease are known as neuronopathic forms of the disorder
because they are characterized by problems that affect the central nervous system. The most
severe type of Gaucher disease is called the perinatal lethal form. This condition causes severe or
life-threatening complications starting before birth or in infancy.
26. Homocystinuria
Homocystinuria is an inherited disorder in which the body is unable to process certain
building blocks of proteins (amino acids) properly. The most common form of homocystinuria is
characterized by nearsightedness (myopia), dislocation of the lens at the front of the eye, an
increased risk of abnormal blood clotting, and brittle bones that are prone to fracture
(osteoporosis) or other skeletal abnormalities. Less common forms of homocystinuria can cause
intellectual disability, failure to grow and gain weight at the expected rate (failure to thrive),
seizures, problems with movement, and a blood disorder called megaloblastic anemia. The signs
and symptoms of homocystinuria typically develop within the first year of life, although some
mildly affected people may not develop features until later in childhood or adulthood.
27. Menkes Disease
Menkes syndrome is a disorder that affects copper levels in the body. It is characterized by
sparse, kinky hair; failure to gain weight and grow at the expected rate (failure to thrive); and
deterioration of the nervous system. Children with Menkes syndrome typically begin to develop
symptoms during infancy and often do not live past age 3. Early treatment with copper may
improve the prognosis in some affected individuals. In rare cases, symptoms begin later in
28. Pfeiffer Syndrome
Pfeiffer syndrome is a genetic disorder characterized by the premature fusion of certain skull
bones (craniosynostosis). This early fusion prevents the skull from growing normally and affects
the shape of the head and face. Pfeiffer syndrome also affects bones in the hands and feet.
Abnormal growth of these bones leads to bulging and wide-set eyes, a high forehead, an
underdeveloped upper jaw, and a beaked nose. In people with Pfeiffer syndrome, the thumbs and
first (big) toes are wide and bend away from the other digits. Unusually
short fingers and toes (brachydactyly) are also common, and there may be some webbing
or fusion between the digits (syndactyly).
29. Primary Ciliary Disease
Primary ciliary dyskinesia is a disorder characterized by chronic respiratory tract infections,
abnormally positioned internal organs, and the inability to have children (infertility). The signs
and symptoms of this condition are caused by abnormal cilia and flagella. Cilia are microscopic,
finger-like projections that stick out from the surface of cells. They are found in the linings of the
airway, the reproductive system, and other organs and tissues. Primary ciliary dyskinesia can
also lead to infertility. Vigorous movements of the flagella are necessary to propel the sperm
cells forward to the female egg cell. Because their sperm do not move properly, males
with primary ciliary dyskinesia are usually unable to father children. Infertility occurs in some
affected females and is likely due to abnormal cilia in the fallopian tubes
30. Stickler Syndrome
Stickler syndrome is a group of hereditary conditions characterized by a distinctive facial
appearance, eye abnormalities, hearing loss, and joint problems. A characteristic feature
of Stickler syndrome is a somewhat flattened facial appearance. This appearance results from
underdeveloped bones in the middle of the face, including the cheekbones and the bridge of the
nose. A particular group of physical features called Pierre Robin sequence is also common in
people with Stickler syndrome. Pierre Robin sequence includes an opening in the roof of the
mouth (a cleft palate), a tongue that is placed further back than normal (glossoptosis), and a
small lower jaw (micrognathia). This combination of features can lead to feeding problems and
difficulty breathing.
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