Microcephalic Primordial Dwarfism, Montreal Type

Introduction

Primordial dwarfism is a group of rare genetic disorders that causes growth retardation from the fetal stage and throughout life. The individuals affected by primordial dwarfism are smaller and have many clinical signs and symptoms. Primordial dwarfism occurs due to a delay in growth in the earlier stages of the fetus. The conditions under primordial dwarfism include Silver-Russell syndrome, Seckel syndrome, microcephalic osteoplastic primordial dwarfism and its types, and Meier-Gorlin syndrome.

What Is Microcephalic Primordial Dwarfism, Montreal Type?

Microcephalic primordial syndrome, Montreal type, is a rare genetic dysmorphic disorder. It is a collection of multiple congenital anomalies mainly characterized by craniofacial anomalies and a severe short stature. This syndrome is also called bird-headed dwarfism, with features of premature senility (aging). This syndrome is very rare, and its incidence is about one in one million people. Less than 1000 cases have been identified in the US.

What Is the Cause of Microcephalic Primordial Dwarfism, Montreal Type?

This syndrome is caused due to changes in the genetic material of an individual. The exact cause and the gene affected are not known. The mode of inheritance of microcephalic primordial dwarfism, Montreal type, is believed to be autosomal recessive. The child gets affected by the condition if the child inherits a copy of the mutated gene from both parents.

What Are the Clinical Signs and Symptoms of Microcephalic Primordial Dwarfism, Montreal Type?

Numerous symptoms are associated with this syndrome, and the symptoms start appearing as a newborn and infant. The severity and the number of symptoms vary among different affected individuals. Some of the signs and symptoms are listed below.

• Severe short stature is well below normal for their age and sex.

• Craniofacial features

  • Low-set ears with absent or small earlobes.

  • High-arched palate or cleft palate.

  • Microcephaly - smaller head circumference.

  • The low posterior hairline, that is, the hair on the neck, extends lower than usual.

  • Micrognathia - Smaller mandible due to developmental hypoplasia of the mandible (lower jaw).

  • Open bite - The upper and lower teeth (dental arches) does not meet with a visible space present in between them.

  • Convex nasal ridge.

  • Tooth decay in multiple teeth.

  • Abnormal amount of hair.

  • Scalp hair loss (alopecia of the scalp).

• Abnormal dermatoglyphics - There is an abnormality of the fingerprints, which are present in the toes, soles, fingers, and palms.

• Congenital pyloric atresia (obstruction of the lower part of the stomach).

• Cryptorchidism - This is also called undescended testis, in which the absence of one or both the testes from the scrotum due to failure of the testis to descend through the inguinal canal to the scrotum.

• The absence of normal moisture characterizes dry skin.

• Hyperreflexia - Hyperactive stretch reflexes of the muscles.

• Hyperhidrosis is excessive sweating even without stimuli like humid or hot weather.

• Intellectual disability, previously known as mental retardation, is a condition in which the person has IQ below 70. Intellectual disabilities of varying degrees are seen in almost all cases of microcephalic primordial dwarfism, minstrel type.

• Hypertonia is when increased muscle tone makes the arms and legs stiff and difficult to move.

• Kyphosis - Increased anterior convexity of the thoracic spine.

• Scoliosis - The presence of abnormal lateral curvature of the spine.

• Lipoatrophy is defined as the loss of local fat tissue.

• Premature aging or senility - This is characterized by premature graying and loss of scalp hair, dry and wrinkled skin in the palms, and a prematurely aged appearance.

• Reduced bone density.

• Ptosis - The upper eyelid margin is positioned lower than normal.

• Wide intermamillary distance - The distance between both nipples is larger than usual.

• Shagreen patch - This is a slightly elevated, irregularly shaped, thickened, skin-colored patch usually seen in the lower back.

• Vertebral segmentation defects are caused due to abnormality in the vertebral separation during development.

• Abnormalities in the EEG (electroencephalogram).

How Is Microcephalic Primordial Dwarfism, Montreal Type Diagnosed?

This syndrome may be diagnosed or suspected before birth if the small head and other craniofacial features are noted during ultrasound imaging. Clinical evaluation of the patient and imaging tests assist in diagnosing the condition. Family and medical history are also obtained to help with the diagnosis. Gene testing can be done to confirm the diagnosis either before or after birth.

What Are the Other Conditions Similar to Microcephalic Primordial Dwarfism, Montreal Type?

• This syndrome is closely associated with Seckel syndrome, which is a type of primordial dwarfism resulting in growth delays, microcephaly, and distinct facial features.

• Meier-Gorlin syndrome is a type of primordial dwarfism with features like microcephaly, short stature, and absent or underdeveloped kneecaps.

• Majewski osteodysplastic primordial dwarfism type II features severe growth delays, skeletal abnormalities, and a characteristic appearance.

• Microcephalic primordial dwarfism may also have symptoms similar to the other types of primordial dwarfism.

How Is Microcephalic Primordial Dwarfism, Montreal Type Managed?

The management of bird-head dwarfism, Montreal type, is focused on addressing the specific complications and symptoms associated with the condition. There is no cure for the syndrome. Therefore management involves a multidisciplinary approach to support and improve the quality of life. Some of the treatment strategies include

• Symptom-Specific Interventions - Depending on the individual’s symptoms, various interventions can be used to manage specific health issues. Some treatments are physical therapy, speech therapy, medications for neurological and other problems, dental treatments, etc.

• Routine Medical Care - People with this syndrome may require frequent medical monitoring to assess their health and manage complications. This may include regular check-ups with specialists like pediatricians, neurologists, orthopedists, and ophthalmologists.

• Supportive Care - Individuals affected by this type of primordial dwarfism and their families may benefit from various types of supportive care, such as counseling or psychological support, educational support, and social support from support groups.

• Genetic Counseling - Affected individuals and their families may benefit from genetic counseling to better understand the inheritance pattern and risk of passing the condition on to future children.

Conclusion

Microcephalic primordial dwarfism, Montreal type, is a rare condition in which the affected individuals have short stature, bird-like facial features, and a variety of symptoms affecting various body systems. While there is no cure for this syndrome and its significant challenges, appropriate care and support may help individuals lead fulfilling lives.