Campomelic dysplasia

Last updated
Campomelic dysplasia
Autosomal dominant - en.svg
This condition is usually inherited in an autosomal dominant manner
Specialty Medical genetics

Campomelic dysplasia (CMD) is a genetic disorder characterized by bowing of the long bones and many other skeletal and extraskeletal features. [1] It can be lethal in the neonatal period due to respiratory insufficiency, but the severity of the disease is variable, and a significant proportion of 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.[ citation needed ]

Contents

Signs and symptoms

While the definitive presentation of the disease is a patient having bowed lower limbs and sex reversal in 46,XY males, there are other clinical criteria that can be used, absent these characteristics, to make the diagnosis. Patients may present with shortened and angulated lower limbs, a vertically oriented and narrow pelvis, an enlarged head, an undersized jaw, cleft palate, flat nasal bridge, low set ears, club feet. On radiographs, underdeveloped shoulder blades, dislocated hips, hypoplastic vertebral pedicles in the thoracic region, 11 pairs of ribs instead of 12, or kyphosis of the cervical spine are useful diagnostic clues. Respiratory distress can be caused by an underdeveloped trachea which collapses on inhalation or by insufficient rib cage development.[ citation needed ]

Genetics

CMD is commonly caused by chromosomal abnormalities in or around the gene SOX9 on the long arm of chromosome 17, specifically at position 17q24, generally spontaneously arising or de novo mutations. Also, numerous single nucleotide variants been identified involving the SOX9 gene that cause some form of CMD. The SOX9 gene codes for a protein transcription factor which, when expressed at the embryonic stage, plays an important role in determining sexual characteristics and greatly influences skeletal development. When the SRY gene of the Y chromosome is expressed in human embryos, a cascade of gene interactions controlled by SOX9 begins and ultimately leads to male gender.[ citation needed ]. Any mutation within the coding region of SOX9 can cause campomelic dysplasia and 75% of the reported mutations lead to sex reversal.

Four major classes of heterozygous SOX9 mutations can cause CMD: amino acid substitutions in the HMG-box, truncations or frameshifts that alter the C-terminal end, mutations at the splice junction, and chromosomal translocations. Additionally, mutations upstream from SOX9 can also cause CMD. Several researchers have reported cis-acting control elements upstream of SOX9. Translocation breakpoints scattered over 1Mb proximal to SOX9 indicate the presence of an extended control region.[ citation needed ]

The lack of correlation between specific genetic mutations and observed phenotype, particularly with regard to sex reversal, give clear evidence of the variable expressivity of the disease.

Milder forms of the disease, seen in those who live beyond the neonatal period and those with ACD, may perhaps be attributable to somatic mosaicism—particularly for those with mutations within the SOX9 coding region. [2] Chromosomal aberrations in the upstream control regions or residual activity of the mutant SOX9 protein could also be responsible for the milder forms of the disease. [2] Long-term survivors of CMD are significantly more likely to have translocation and inversion mutations upstream of SOX9 rather than mutations in the SOX9 coding region itself.[ citation needed ]

Diagnosis

In utero sonographic diagnosis is possible when characteristic features such as bilateral bowed femurs and tibia, clubbed feet, prominent curvature of the neck, a bell-shaped chest, pelvic dilation, and/or an undersized jaw are apparent. [3] Radiographic techniques are generally used only postnatally and also rely on prototypical physical characteristics. [4] However, bent bones are an unspecific sign and most fetuses with bent bones will have conditions other than campomelic dysplasia [5]

Screening

Genetic screening can be done by comparative genomic hybridization (CGH) studies using DNA microarrays, and by PCR and sequencing of the entire SOX9 gene. Many different translocation breakpoints and related chromosomal aberrations in patients with CMD have been identified.

Prognosis

In more than half of the cases, death occurs in the neonatal period due to respiratory distress, generally related to small chest size or insufficient development of the trachea and other upper airway structures. [2]

Among survivors of CMD, the skeletal malformations change over time to include worsening scoliosis or kyphosis resulting in decreased trunk size relative to the limb length. Neurological damage is also often seen including spinal cord compression and deafness. Even among survivors of the prenatal period, CMD patients have shortened life spans due to lifelong respiratory issues. Those patients with ambiguous genitalia or sex reversal at birth, of course, maintain that state, and are either sterile or have reduced fertility.[ citation needed ]

Epidemiology

Campomelic dysplasia has a reported incidence of 0.05-0.09 per 10000 live births.[ citation needed ]

Related Research Articles

<span class="mw-page-title-main">Autosome</span> Any chromosome other than a sex chromosome

An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal pairs, which may have different structures. The DNA in autosomes is collectively known as atDNA or auDNA.

<span class="mw-page-title-main">Sex-determining region Y protein</span> Protein that initiates male sex determination in therian mammals

Sex-determining region Y protein (SRY), or testis-determining factor (TDF), is a DNA-binding protein encoded by the SRY gene that is responsible for the initiation of male sex determination in therian mammals. SRY is an intronless sex-determining gene on the Y chromosome. Mutations in this gene lead to a range of disorders of sex development with varying effects on an individual's phenotype and genotype.

<span class="mw-page-title-main">Spondyloperipheral dysplasia</span> Medical condition

Spondyloperipheral dysplasia is an autosomal dominant disorder of bone growth. The condition is characterized by flattened bones of the spine (platyspondyly) and unusually short fingers and toes (brachydactyly). Some affected individuals also have other skeletal abnormalities, short stature, nearsightedness (myopia), hearing loss, and mental retardation. Spondyloperipheral dysplasia is a subtype of collagenopathy, types II and XI.

<span class="mw-page-title-main">Achondrogenesis type 1B</span> Medical condition

Achondrogenesis type 1B is a severe autosomal recessive skeletal disorder, invariably fatal in the perinatal period. It is distinguished by its elongated, spherical midsection, small chest, and exceedingly short limbs. The feet can turn inward and upward (clubfeet), and the fingers and toes are little. Babies affected often have a soft out-pouching at the groin or around the belly button.

<span class="mw-page-title-main">Cartilage–hair hypoplasia</span> Medical condition

Cartilage–hair hypoplasia (CHH) is a rare genetic disorder. Symptoms may include short-limbed dwarfism due to skeletal dysplasia, variable level of immunodeficiency, and predisposition to cancer. It was first reported by Victor McKusick in 1965.

<span class="mw-page-title-main">Autosomal recessive multiple epiphyseal dysplasia</span> Medical condition

Autosomal recessive multiple epiphyseal dysplasia (ARMED), also called epiphyseal dysplasia, multiple, 4 (EDM4), multiple epiphyseal dysplasia with clubfoot or –with bilayered patellae, is an autosomal recessive congenital disorder affecting cartilage and bone development. The disorder has relatively mild signs and symptoms, including joint pain, scoliosis, and malformations of the hands, feet, and knees.

An osteochondrodysplasia, or skeletal dysplasia, is a disorder of the development of bone and cartilage. Osteochondrodysplasias are rare diseases. About 1 in 5,000 babies are born with some type of skeletal dysplasia. Nonetheless, if taken collectively, genetic skeletal dysplasias or osteochondrodysplasias comprise a recognizable group of genetically determined disorders with generalized skeletal affection. These disorders lead to disproportionate short stature and bone abnormalities, particularly in the arms, legs, and spine. Skeletal dysplasia can result in marked functional limitation and even mortality.

<span class="mw-page-title-main">Multiple epiphyseal dysplasia</span> Rare genetic disorder

Multiple epiphyseal dysplasia (MED), also known as Fairbank's disease, is a rare genetic disorder that affects the growing ends of bones. Long bones normally elongate by expansion of cartilage in the growth plate near their ends. As it expands outward from the growth plate, the cartilage mineralizes and hardens to become bone (ossification). In MED, this process is defective.

<span class="mw-page-title-main">Disorders of sex development</span> Medical conditions involving the development of the reproductive system

Disorders of sex development (DSDs), also known as differences in sex development or variations in sex characteristics (VSC), are congenital conditions affecting the reproductive system, in which development of chromosomal, gonadal, or anatomical sex is atypical.

<span class="mw-page-title-main">SOX9</span> Transcription factor gene of the SOX family

Transcription factor SOX-9 is a protein that in humans is encoded by the SOX9 gene.

<span class="mw-page-title-main">Boomerang dysplasia</span> Medical condition

Boomerang dysplasia is a lethal form of osteochondrodysplasia known for a characteristic congenital feature in which bones of the arms and legs are malformed into the shape of a boomerang. Death usually occurs in early infancy due to complications arising from overwhelming systemic bone malformations.

<span class="mw-page-title-main">Cranio-lenticulo-sutural dysplasia</span> Medical condition

Cranio-lenticulo-sutural dysplasia is a neonatal/infancy disease caused by a disorder in the 14th chromosome. It is an autosomal recessive disorder, meaning that both recessive genes must be inherited from each parent in order for the disease to manifest itself. The disease causes a significant dilation of the endoplasmic reticulum in fibroblasts of the host with CLSD. Due to the distension of the endoplasmic reticulum, export of proteins from the cell is disrupted.

<span class="mw-page-title-main">Parastremmatic dwarfism</span> Medical condition

Parastremmatic dwarfism is a rare bone disease that features severe dwarfism, thoracic kyphosis, a distortion and twisting of the limbs, contractures of the large joints, malformations of the vertebrae and pelvis, and incontinence. The disease was first reported in 1970 by Leonard Langer and associates; they used the term parastremmatic from the Greek parastremma, or distorted limbs, to describe it. On X-rays, the disease is distinguished by a "flocky" or lace-like appearance to the bones. The disease is congenital, which means it is apparent at birth. It is caused by a mutation in the TRPV4 gene, located on chromosome 12 in humans. The disease is inherited in an autosomal dominant manner.

Liebenberg syndrome is a rare autosomal genetic disease that involves a deletion mutation upstream of the PITX1 gene, which is one that's responsible for the body's organization, specifically in forming lower limbs. In animal studies, when this deletion was introduced to developing birds, their wing buds were noted to take on limb-like structures.

Langer Mesomelic Dysplasia (LMD) is a rare congenital disorder characterised by altered bone formation, which typically causes affected individuals to experience shortening of the bones of the extremities as well as an abnormally short stature.

Acromesomelic dysplasia is a rare skeletal disorder that causes abnormal bone and cartilage development, leading to shortening of the forearms, lower legs, hands, feet, fingers, and toes. Five different genetic mutations have been implicated in the disorder. Treatment is individualized but is generally aimed at palliating symptoms, for example, treatment of kyphosis and lumbar hyperlordosis.

<span class="mw-page-title-main">Atelosteogenesis type I</span> Medical condition

Atelosteogenesis type I is a rare autosomal dominant condition. This condition is evident at birth and is associated with a very poor prognosis for the baby. It may be diagnosed antenatally.

<span class="mw-page-title-main">Andrea Superti-Furga</span> Swiss and Italian paediatrician, geneticist and molecular biologist

Andrea Superti-Furga is a Swiss-Italian pediatrician, geneticist and molecular biologist. He is the head of the Division of Genetic Medicine at the Lausanne University Hospital (CHUV) and a professor at the Faculty of Medicine and Biology of the University of Lausanne.

Cousin syndrome is a genetic condition characterized by short stature at birth, a short neck with low-positioned external ears, as well as congenital malformations of the skeletal system affecting the shoulders, the pelvis, the neck, and the limbs. The condition determines physical disability, particularly affecting deambulation, and hearing loss while intelligence is not affected.

<span class="mw-page-title-main">Schneckenbecken dysplasia</span> Medical condition

Schneckenbecken dysplasia is a rare pre-natally fatal hereditary autosomal recessive condition which affects the bones and pre-natal growth.

References

  1. Unger S, Scherer G, Superti-Furga A. Campomelic Dysplasia. 2008 Jul 31 [Updated 2021 Mar 18]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1760/
  2. 1 2 3 S. Corbani; E. Chouery; B. Eid; et al. (2010). "Mild Campomelic Dysplasia: Report on a Case and Review". Mol Syndromol. 1 (4): 163–168. doi:10.1159/000322861. PMC   3042119 . PMID   21373255.
  3. K. Eger (2005). "Campomelic Dysplasia". J Diag Medical Sonography. 21 (4): 345–349. doi: 10.1177/8756479305278970 . S2CID   208502617.
  4. J. Goyal; A. Gupta; V. Shah (2011). "Campomelic dysplasia". Indian J Hum Genet. 17 (3): 247–248. doi: 10.4103/0971-6866.92085 . PMC   3277002 . PMID   22346005.
  5. A Superti-Furga, S Unger; Prenatal Diagnosis of Skeletal Dysplasias and Connective Tissue Disorders. In: Genetic Disorders and the Fetus, 8th edition 2021 (A. Milunky and J. Milunsky, eds), John Wiley & Sons Ltd, pp. 783-802, Print ISBN   9781119676935, Online ISBN   9781119676980, doi : 10.1002/9781119676980