Question: What is (are) Koolen de Vries syndrome ?
Answer: Koolen de Vries syndrome, formerly known as 17q21.31 microdeletion syndrome, is a condition caused by a small deletion of genetic material from chromosome 17. The deletion occurs at a location designated as q21.31. People with 17q21.31 microdeletion syndrome may have developmental delay, intellectual disability, seizures, hypotonia. distinctive facial features, and vision problems. Some affected individuals have heart defects, kidney problems, and skeletal anomalies such as foot deformities. Typically their disposition is described as cheerful, sociable, and cooperative. The exact size of the deletion varies among affected individuals, but it contains at least six genes. This deletion affects one of the two copies of chromosome 17 in each cell. The signs and symptoms of 17q21.31 microdeletion syndrome are probably related to the loss of one or more genes in this region.
Source: GARD

Question: What are the symptoms of Koolen de Vries syndrome ?
Answer: What are the signs and symptoms of Koolen de Vries syndrome? The Human Phenotype Ontology provides the following list of signs and symptoms for Koolen de Vries 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) Cognitive impairment 90% Generalized hypotonia 90% Abnormality of hair texture 75% Feeding difficulties in infancy 75% High palate 75% Joint hypermobility 75% Narrow palate 75% Nasal speech 75% Prominent fingertip pads 75% Long face 74% Cryptorchidism 71% Arachnodactyly 61% Seizures 55% Abnormality of the cardiac septa 50% Aplasia/Hypoplasia of the corpus callosum 50% Blepharophimosis 50% Broad forehead 50% Bulbous nose 50% Coarse facial features 50% Conspicuously happy disposition 50% Delayed speech and language development 50% Displacement of the external urethral meatus 50% Epicanthus 50% High forehead 50% High, narrow palate 50% Hypermetropia 50% Hypopigmentation of hair 50% Macrotia 50% Microdontia 50% Neurological speech impairment 50% Overfolded helix 50% Pear-shaped nose 50% Ptosis 50% Strabismus 50% Upslanted palpebral fissure 50% Ventriculomegaly 50% Broad chin 42% Hip dislocation 33% Hip dysplasia 33% Hypotrophy of the small hand muscles 33% Kyphosis 33% Narrow palm 33% Positional foot deformity 33% Scoliosis 33% Abnormality of dental enamel 7.5% Abnormality of the aortic valve 7.5% Cataract 7.5% Cleft palate 7.5% Dry skin 7.5% Hypothyroidism 7.5% Ichthyosis 7.5% Microcephaly 7.5% Pectus excavatum 7.5% Prominent nasal bridge 7.5% Pyloric stenosis 7.5% Reduced number of teeth 7.5% Short stature 7.5% Small for gestational age 7.5% Underdeveloped nasal alae 7.5% Vesicoureteral reflux 7.5% Wide nasal bridge 7.5% Aortic dilatation 5% Hypotelorism 5% Prominent metopic ridge 5% Spondylolisthesis 5% Vertebral fusion 5% Anteverted ears - Atria septal defect - Autosomal dominant inheritance - Bicuspid aortic valve - Cleft upper lip - Contiguous gene syndrome - Eczema - Failure to thrive - Hydronephrosis - Intellectual disability - Intrauterine growth retardation - Open mouth - Poor speech - Pulmonic stenosis - Sacral dimple - Sporadic - Variable expressivity - Ventricular septal defect - Wide intermamillary distance - Widely spaced teeth - 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