Dyggve-Melchior-Clausen syndrome

Alternate names

Dyggve-Melchior-Clausen disease; DMC syndrome

Definition

Dyggve-Melchior-Clausen (DMC) syndrome is a rare, progressive genetic condition characterized by abnormal skeletal development, microcephaly, and intellectual disability.

Epidemiology

Only about 100 cases have been reported to date.

Cause

DMC is caused by mutations in the DYM gene.

Inheritance

Autosomal recessive inheritance, a 25% chance

It is inherited in an autosomal recessive manner.

Signs and symptoms

• Affected newborns may be small at birth, but otherwise appear normal.
• Skeletal findings are often recognized first between 1 and 18 months. With age, other characteristics begin to develop.
• Chest deformities, feeding difficulties, and developmental delay usually occur before 18 months.
• Disproportionate short stature usually occurs after 18 months. Additional features may include a long skull, distinctive facial appearance, a protruding jaw, microcephaly, and claw-like hands.
• Intellectual disability occurs in most cases, ranging from moderate to severe.
• Affected individuals can also develop a protruding breastbone; spinal abnormalities; abnormal bones in the hands, fingers, toes, wrists, and long bones of the arms and legs; and joint contractures, especially of the elbows and hips.
• Secondary problems resulting from the skeletal abnormalities may include spinal compression, dislocated hips, and restricted joint mobility. These problems may in turn cause a waddling gait.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Abnormality of epiphysis morphology(Abnormal shape of end part of bone)
• Abnormality of the ilium
• Abnormality of the metaphysis(Abnormality of the wide portion of a long bone)
• Genu valgum(Knock knees)
• Global developmental delay
• Hip dislocation(Dislocated hips)
• Intellectual disability(Mental deficiency)
• Micromelia(Smaller or shorter than typical limbs)
• Pectus carinatum(Pigeon chest)
• [[Platyspondyly](Flattened vertebrae)
• Short thorax(Shorter than typical length between neck and abdomen)
• Skeletal dysplasia

30%-79% of people have these symptoms

• Abnormality of the wrist(Abnormalities of the wrists)
• Coarse facial features(Coarse facial appearance)
• Disproportionate short-trunk short stature(Disproportionate short-trunked dwarfism)
• Hyperlordosis(Prominent swayback)
• Hypoplasia of the odontoid process
• Joint stiffness(Stiff joint)
• Kyphosis(Hunched back)
• Microcephaly(Abnormally small skull)
• Neurological speech impairment(Speech disorder)
• Postnatal growth retardation(Growth delay as children)
• Scoliosis
• Short neck(Decreased length of neck)
• Sloping forehead(Inclined forehead)
• Spinal canal stenosis(Narrow spinal canal)

5%-29% of people have these symptoms

• Attention deficit hyperactivity disorder(Attention deficit)
• Autism
• Shoulder dislocation

Diagnosis

• DMC syndrome may be suspected following a thorough clinical evaluation, a detailed patient history, and identification of characteristic findings (e.g., barrel chest, and disproportionate short stature).
• Radiographs may confirm specific skeletal abnormalities and findings consistent with DMC syndrome.
• Genetic testing can also confirm a diagnosis.

Treatment

• Treatment of individuals with DMC syndrome depends on the affected person's symptoms and is usually supportive.
• There is no cure for this condition.
• Treatments might include spinal fusion of the segments of the spinal column at the top of the spine or other means of vertebral stabilization.
• Additional surgical techniques may be used to correct various skeletal abnormalities such as dislocation of the shoulder and hip joints.
• In some cases, hip replacement is required.
• Children with DMC syndrome may benefit from early intervention and special educational programs.

Prognosis

DMC syndrome is a progressive condition, meaning that signs and symptoms worsen over time. The orthopedic complications usually progress, which can include lumbar lordosis, thoracic kyphosis, scoliosis, dislocation in the hip joints, deformed knees, and spinal cord compression. Adult height is severely reduced with height ranging from 82 cm to 128 cm (32 in to 50 in). Neurological complications may include hyperactivity, autistic-like behavior, lack of speech, and mild to severe intellectual disability.

NIH genetic and rare disease info

• NIH info on Dyggve-Melchior-Clausen syndrome

Dyggve-Melchior-Clausen syndrome is a rare disease.

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