Occipital horn syndrome
Encyclopedia
Occipital horn syndrome (OHS), formerly considered a variant of Ehlers-Danlos syndrome
, is an X-linked recessive
connective tissue disorder. It is caused by a deficiency in the transport of the essential mineral copper
, associated with mutations in the ATP7A
gene. Only about 2/3 of children with OHS are thought to have genetically inherited the disorder; the other 1/3 do not have the disease in their family history. Since the disorder is X-linked recessive the disease affects more males. This is because they do not have a second X chromosome, unlike females, so essentially are lacking a 'backup' of the correct genetic information. Females are much more likely to be carriers only. For a female to be affected they must carry two defective X chromosomes, not just one. The disorder is considered a milder variant of Menkes disease
.
copper
excretion that causes deformations in the skeleton
. These include projections on the back of the skull
(parasagittal bone exostoses arising from the occipital bone
—the so-called "occipital horns") as well as deformities of the elbow, radial head dislocation, hammer-shaped lateral ends of the clavicle
s, and abnormalities of the hips and pelvis
.
OHS presents in early to middle childhood. Children may present with features such as:
However, copper histidine injections have been shown ineffective in studies of copper metabolic-connective tissue disorders such as OHS.
Ehlers-Danlos syndrome
Ehlers–Danlos syndrome is a group of inherited connective tissue disorders, caused by a defect in the synthesis of collagen . The collagen in connective tissue helps tissues to resist deformation...
, is an X-linked recessive
X-linked recessive
X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be expressed in males and in females who are homozygous for the gene mutation X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on...
connective tissue disorder. It is caused by a deficiency in the transport of the essential mineral copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, associated with mutations in the ATP7A
ATP7A
Copper-transporting ATPase 1 also known as copper pump 1 or Menkes disease-associated protein is a protein that in humans is encoded by the ATP7A gene.- Gene :...
gene. Only about 2/3 of children with OHS are thought to have genetically inherited the disorder; the other 1/3 do not have the disease in their family history. Since the disorder is X-linked recessive the disease affects more males. This is because they do not have a second X chromosome, unlike females, so essentially are lacking a 'backup' of the correct genetic information. Females are much more likely to be carriers only. For a female to be affected they must carry two defective X chromosomes, not just one. The disorder is considered a milder variant of Menkes disease
Menkes disease
Menkes disease , also called Menkes syndrome, copper transport disease, steely hair disease, kinky hair disease, or Menkes kinky hair syndrome, is a disorder that affects copper levels in the body, leading to copper deficiency...
.
Characteristics
It is characterized by a deficiency in biliaryBile
Bile or gall is a bitter-tasting, dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the process of digestion of lipids in the small intestine. In many species, bile is stored in the gallbladder and upon eating is discharged into the duodenum...
copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
excretion that causes deformations in the skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
. These include projections on the back of the skull
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...
(parasagittal bone exostoses arising from the occipital bone
Occipital bone
The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoidal in shape and curved on itself...
—the so-called "occipital horns") as well as deformities of the elbow, radial head dislocation, hammer-shaped lateral ends of the clavicle
Clavicle
In human anatomy, the clavicle or collar bone is a long bone of short length that serves as a strut between the scapula and the sternum. It is the only long bone in body that lies horizontally...
s, and abnormalities of the hips and pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
.
OHS presents in early to middle childhood. Children may present with features such as:
- Normal/slightly delayed intelligence
- Long neck, high arched palate, long face, high forehead
- Looseness of skin and “double jointed”
- Inguinal Hernias
- Twisting of blood vessels
- Bladder diverticula
- Dysautonomia—inability to regulate parts of the nervous system
- Chronic Diarrhea
- Coarse hair
Treatment
Courses of treatment for children with is dependent upon the severity of their case. Children with OHS often receive physical and occupational therapy. They may require a feeding tube to supplement nourishment if they are not growing enough. In an attempt to improve the neurological condition (seizures) copper histidine or copper chloride injections can be given early in the child’s life.However, copper histidine injections have been shown ineffective in studies of copper metabolic-connective tissue disorders such as OHS.
See also
- Cutis laxaCutis laxaCutis laxa is a group of rare connective tissue disorders in which the skin becomes inelastic and hangs loosely in folds.-Causes:In most cases, cutis laxa is inherited...
- List of cutaneous conditions
- Inborn errors of metal metabolismInborn errors of metal metabolismInborn errors of metal metabolism refers to metabolic disturbances in the processing or distribution of dietary minerals.An example is hemochromatosis....