Hadju Cheney Syndrome

# Overview
Hajdu-Cheney syndrome also known as Cheney Syndrome, HCS is a rare, connective tissue disorder comprising acroosteolysis of the distal phalanges with associated digital abnormalities, distinctive craniofacial and skull changes, dental anomalies, and proportionate short stature. Although the majority of cases are of unknown cause, the presence of multiple cases in one family suggests that autosomal dominant genetic transmission may be possible.The Hajdu-Cheney syndrome (familial idiopathic
acro-osteolysis) was first described in
1948 by Hajdu and Kauntze and more extensively reported by Cheney.

# Genetics
Although the cases of Hadju Cheney Syndrome has been sporadically found, evidences has shown it to be a Autosomal Dominant disease. Some heterogygous nonsense and frameshift mutations in NOTCH2 to the last coding exon of the gene has been shown. The NOTCH signaling pathway is critical for cell-fate determination.Notch2 mutattions are also seen in Alagille Syndrome.

# Clinical Features
- Acroosteolysis i,e breakdown of bone (osteolysis), especially of the outermost bones of the fingers and toes, Osseous compression
Osteoporosis, Osteopenia, reccurent fractures and other skeletal abnormalities. Ossification failure of sutures, Thickened skull vault, Absence of frontal sinus, Elongated sella turcica, Progressive basilar impression, Foramen magnum impaction are also skeletal manifestation of Hadju Cheney Syndrome.
Hydrocephalus
Dysmorphic facies-Prominent eyebrows, Down slanting space between eyelids, Low set ears, Prominent ear lobes, Broad nose, Long philtrum, Small mandible, Resorption of alveolar process, Early loss of teeth, Highly arched palate.
Vertebral Abnormalities-Biconcave vertebrae, Tall lumbar vertebral bodies, Narrow vertebral disk space, Kyphoscoliosis
Joint laxity
Long and bowed fibula
Eye Abnormalities- Cataract, Nystagmus, Protruding eyeballs, Widely spaced eyes, Epicanthal folds, Optic atrophy.
Hearing loss
Abdominal wall laxity resulting in umbilical hernia and inguinal hernia.
- Acroosteolysis i,e breakdown of bone (osteolysis), especially of the outermost bones of the fingers and toes, Osseous compression
- Osteoporosis, Osteopenia, reccurent fractures and other skeletal abnormalities. Ossification failure of sutures, Thickened skull vault, Absence of frontal sinus, Elongated sella turcica, Progressive basilar impression, Foramen magnum impaction are also skeletal manifestation of Hadju Cheney Syndrome.
- Hydrocephalus
- Dysmorphic facies-Prominent eyebrows, Down slanting space between eyelids, Low set ears, Prominent ear lobes, Broad nose, Long philtrum, Small mandible, Resorption of alveolar process, Early loss of teeth, Highly arched palate.
- Vertebral Abnormalities-Biconcave vertebrae, Tall lumbar vertebral bodies, Narrow vertebral disk space, Kyphoscoliosis
- Joint laxity
- Long and bowed fibula
- Eye Abnormalities- Cataract, Nystagmus, Protruding eyeballs, Widely spaced eyes, Epicanthal folds, Optic atrophy.
- Hearing loss
- Abdominal wall laxity resulting in umbilical hernia and inguinal hernia.

# Treatment
The treatment of the disorder is symptomatic and the prognosis is quite good, with the morbidity depending on the bone changes caused by acro-osteolysis and the neurological complications caused by basilar invagination. Since about 2002, some patients with this disorder have been offered drug therapy with bisphosphonates (a class of osteoporosis drugs) to treat problems with bone resorption associated with the bone breakdown and skeletal malformations that characterize this disorder.