Question: What is (are) Myhre syndrome ?
Answer: Myhre syndrome is a rare inherited disorder characterized by intellectual disability, short stature, unusual facial features, and various bone (skeletal) abnormalities. Other findings may include hearing impairment, abnormal enlargement of the muscles (muscle hypertrophy), and/or joint stiffness. Myhre syndrome is caused by mutations in the SMAD4 gene. This condition is inherited in an autosomal dominant pattern. Most cases are due to a new mutation.
Source: GARD

Question: What are the symptoms of Myhre syndrome ?
Answer: What are the signs and symptoms of Myhre syndrome? Myhre syndrome is a condition with features affecting many systems and functions of the body. Associated findings might include: Delayed development of language and motor skills such as crawling and walking Intellectual disability that ranges from mild to moderate Behavioral issues such as features of autism or related developmental disorders affecting communication and social interaction Hearing loss, which can be caused by changes in the inner ear (sensorineural deafness), changes in the middle ear (conductive hearing loss), or both (mixed hearing loss) Reduced growth, beginning before birth and continuing through adolescence and affecting weight and height (many are shorter than about 97 percent of their peers) Stiffness of the skin resulting in a muscular appearance Skeletal abnormalities including thickening of the skull bones, flattened bones of the spine (platyspondyly), broad ribs, underdevelopment of the winglike structures of the pelvis (hypoplastic iliac wings), and unusually short fingers and toes (brachydactyly) Joint problems (arthropathy), including stiffness and limited mobility Typical facial features including narrow openings of the eyelids (short palpebral fissures), a shortened distance between the nose and upper lip (a short philtrum), a sunken appearance of the middle of the face (midface hypoplasia), a small mouth with a thin upper lip, and a protruding jaw (prognathism) An opening in the roof of the mouth (a cleft palate), a split in the lip (a cleft lip), or both Constriction of the throat (laryngotracheal stenosis) High blood pressure (hypertension) Heart or eye abnormalities In males, undescended testes (cryptorchidism) The Human Phenotype Ontology provides the following list of signs and symptoms for Myhre syndrome. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Abnormality of pelvic girdle bone morphology 90% Abnormality of the ribs 90% Brachydactyly syndrome 90% Cognitive impairment 90% Craniofacial hyperostosis 90% Hearing impairment 90% Intrauterine growth retardation 90% Limitation of joint mobility 90% Malar flattening 90% Mandibular prognathia 90% Narrow mouth 90% Platyspondyly 90% Short philtrum 90% Short stature 90% Skeletal muscle hypertrophy 90% Thin vermilion border 90% Abnormality of the cardiac septa 50% Abnormality of the metaphyses 50% Blepharophimosis 50% Cryptorchidism 50% EMG abnormality 50% Hypermetropia 50% Hypertension 50% Ptosis 50% Thickened skin 50% Behavioral abnormality 7.5% Cataract 7.5% Cleft palate 7.5% Displacement of the external urethral meatus 7.5% Hernia of the abdominal wall 7.5% Non-midline cleft lip 7.5% Precocious puberty 7.5% Ataxia 5% Microphthalmia 5% Obesity 5% Oral cleft 5% Respiratory failure 5% Respiratory insufficiency 5% 2-3 toe syndactyly - Abnormality of the voice - Aortic valve stenosis - Autism - Autosomal dominant inheritance - Broad ribs - Camptodactyly - Clinodactyly - Coarctation of aorta - Cone-shaped epiphysis - Deeply set eye - Enlarged vertebral pedicles - Fine hair - Generalized muscle hypertrophy - Hypertelorism - Hypoplasia of midface - Hypoplasia of the maxilla - Hypoplastic iliac wing - Intellectual disability - Laryngotracheal stenosis - Low-set ears - Microcephaly - Microtia - Overlapping toe - Patent ductus arteriosus - Pericardial effusion - Prominent nasal bridge - Radial deviation of finger - Seizures - Short finger - Short long bone - Short neck - Short toe - Sparse hair - Stiff skin - Strabismus - Thick eyebrow - Thickened calvaria - Vertebral fusion - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
Source: GARD

Question: What causes Myhre syndrome ?
Answer: What causes Myhre syndrome? Myhre syndrome is caused by mutations in the SMAD4 gene. This gene provides instructions for making a protein involved in transmitting chemical signals from the cell surface to the nucleus. This signaling pathway, called the transforming growth factor beta (TGF-) pathway, allows the environment outside the cell to affect how the cell produces other proteins. As part of this pathway, the SMAD4 protein interacts with other proteins to control the activity of particular genes. These genes influence many areas of development. Some researchers believe that the SMAD4 gene mutations that cause Myhre syndrome impair the ability of the SMAD4 protein to attach (bind) properly with the other proteins involved in the signaling pathway. Other studies have suggested that these mutations result in an abnormally stable SMAD4 protein that remains active in the cell longer. Changes in SMAD4 binding or availability may result in abnormal signaling in many cell types, which affects development of several body systems and leads to the signs and symptoms of Myhre syndrome.
Source: GARD

Question: Is Myhre syndrome inherited ?
Answer: How is Myhre syndrome inherited? This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Most cases result from new (de novo) mutations in the gene that occur during the formation of reproductive cells (eggs or sperm) or in early embryonic development. These cases occur in people with no history of the disorder in their family.
Source: GARD

Question: What are the treatments for Myhre syndrome ?
Answer: How might Myhre syndrome be treated? Treatment of this condition is symptomatic and supportive. Children with Myhre syndrome may require management by a team of specialists, including pediatricians, speech pathologists, orthopedists (bone specialists), cardiologists (heart specialists), audiologists (hearing specialists), and physical therapists. Early intervention is important to help ensure that children with Myhre syndrome reach their full potential.
Source: GARD