OSTEOPETROSIS
Osteopetrosis is marked by increased bone density due to a
defect in bone reabsorption by cells called osteoclasts. This
leads to accumulation of bone with defective architecture,
making them brittle and susceptible to fracture. In some cases,
this is also accompanied by skeletal abnormalities.
Classifications
There are three types of osteopetrosis, classified by their mode
of inheritance:
• Autosomal dominant
• autosomal recessive
• X-linked recessive.
Autosomal dominant
It is the most common: usually, patients have mild symptoms
that present in late childhood to adulthood.
Autosomal recessive
It is also called the malignant infantile type, is apparent soon
after birth and frequently shortens life expectancy.
X-linked recessive
This form of osteopetrosis is extremely rare.
There is also anintermediate type of osteopetrosis, comprising
both milder autosomal recessive forms and dominant ones with
early and severe presentation.
Signs & Symptoms
Although symptoms may not initially be apparent in people
with mild forms of this disorder, trivial injuries may cause bone
, fractures due to bone fragility. Symptoms include fractures, low
blood cell production, and loss of cranial nerve function causing
blindness, deafness, and/or facial nerve paralysis. Affected
individuals may experience frequent infections of teeth and the
bone in the jaw.
Osteopetrosis, Autosomal Recessive; Malignant Infantile Type
The most severe type of osteopetrosis, malignant infantile type,
is apparent from birth and if left untreated, can lead to death in
the first decade of life. Symptoms vary depending on the exact
gene change. Affected individuals may have an abnormally
large head (macrocephaly). They may also have hydrocephalus,
characterized by inhibition of the normal flow of cerebrospinal
fluid (CSF) within and abnormal widening (dilatation) of the
cerebral spaces of the brain (ventricles), causing accumulation
of CF in the skull and potentially increased pressure on brain
tissue.Symptoms that affect the eyes may include wasting away
(atrophy) of the retina, eyes that appear widely spaced
(hypertelorism), eyes that protrude from their orbits
(exophthalmos), cross-eyes (strabismus), involuntary rhythmic
movements of the eyes (nystagmus), and blindness.
Osteopetrosis, Autosomal Dominant; Adult Type
A milder form of osteopetrosis, the adult type, is usually
diagnosed in late childhood or adulthood. There is
predominance of bone symptoms, including osteosclerosis,
fractures after minimal trauma (usually of the ribs and long
bones), osteomyelitis and cranial hyperostosis. In some cases,
affected individuals may have dental abscess. In many cases,
Osteopetrosis is marked by increased bone density due to a
defect in bone reabsorption by cells called osteoclasts. This
leads to accumulation of bone with defective architecture,
making them brittle and susceptible to fracture. In some cases,
this is also accompanied by skeletal abnormalities.
Classifications
There are three types of osteopetrosis, classified by their mode
of inheritance:
• Autosomal dominant
• autosomal recessive
• X-linked recessive.
Autosomal dominant
It is the most common: usually, patients have mild symptoms
that present in late childhood to adulthood.
Autosomal recessive
It is also called the malignant infantile type, is apparent soon
after birth and frequently shortens life expectancy.
X-linked recessive
This form of osteopetrosis is extremely rare.
There is also anintermediate type of osteopetrosis, comprising
both milder autosomal recessive forms and dominant ones with
early and severe presentation.
Signs & Symptoms
Although symptoms may not initially be apparent in people
with mild forms of this disorder, trivial injuries may cause bone
, fractures due to bone fragility. Symptoms include fractures, low
blood cell production, and loss of cranial nerve function causing
blindness, deafness, and/or facial nerve paralysis. Affected
individuals may experience frequent infections of teeth and the
bone in the jaw.
Osteopetrosis, Autosomal Recessive; Malignant Infantile Type
The most severe type of osteopetrosis, malignant infantile type,
is apparent from birth and if left untreated, can lead to death in
the first decade of life. Symptoms vary depending on the exact
gene change. Affected individuals may have an abnormally
large head (macrocephaly). They may also have hydrocephalus,
characterized by inhibition of the normal flow of cerebrospinal
fluid (CSF) within and abnormal widening (dilatation) of the
cerebral spaces of the brain (ventricles), causing accumulation
of CF in the skull and potentially increased pressure on brain
tissue.Symptoms that affect the eyes may include wasting away
(atrophy) of the retina, eyes that appear widely spaced
(hypertelorism), eyes that protrude from their orbits
(exophthalmos), cross-eyes (strabismus), involuntary rhythmic
movements of the eyes (nystagmus), and blindness.
Osteopetrosis, Autosomal Dominant; Adult Type
A milder form of osteopetrosis, the adult type, is usually
diagnosed in late childhood or adulthood. There is
predominance of bone symptoms, including osteosclerosis,
fractures after minimal trauma (usually of the ribs and long
bones), osteomyelitis and cranial hyperostosis. In some cases,
affected individuals may have dental abscess. In many cases,
