- Polyhydramnios (HP:0001561): The presence of excess amniotic fluid in the uterus during pregnancy. Evidence: IEA. (OMIM:160900)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: IEA. (OMIM:160900)
- Cerebral atrophy (HP:0002059): Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum. Evidence: TAS. (OMIM:160900)
- Myotonia (HP:0002486): An involuntary and painless delay in the relaxation of skeletal muscle following contraction or electrical stimulation. Evidence: TAS. (OMIM:160900)
- Respiratory distress (HP:0002098): Respiratory distress is objectively observable as the physical or emotional consequences from the experience of dyspnea. The physical presentation of respiratory distress is generally referred to as labored breathing, while the sensation of respiratory distress is called shortness of breath or dyspnea. Evidence: IEA. (OMIM:160900)
- First degree atrioventricular block (HP:0011705): Delay of conduction through the atrioventricular node, which is manifested as prolongation of the PR interval in the electrocardiogram (EKG). All atrial impulses reach the ventricles. Evidence: PCS. (OMIM:160900)
- Hypotonia (HP:0001252): Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist. Evidence: IEA. (OMIM:160900)
- Atrial fibrillation (HP:0005110): An atrial arrhythmia characterized by disorganized atrial activity without discrete P waves on the surface EKG, but instead by an undulating baseline or more sharply circumscribed atrial deflections of varying amplitude an frequency ranging from 350 to 600 per minute. Evidence: PCS. Frequency: 1/11. (PMID:15557517)
- Excessive daytime somnolence (HP:0001262): A state of abnormally strong desire for sleep during the daytime. Evidence: TAS. (OMIM:160900)
- Cholelithiasis (HP:0001081): Hard, pebble-like deposits that form within the gallbladder. Evidence: IEA. (OMIM:160900)
- Frontal balding (HP:0002292): Absence of hair in the anterior midline and/or parietal areas. Evidence: IEA. (OMIM:160900)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: TAS. (OMIM:160900)
- Severe intellectual disability (HP:0010864): Severe intellectual disability (ID) is defined as a type of ID characterized by severely sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 20-34. Evidence: TAS. Onset: Congenital onset (HP:0003577). (OMIM:160900)
- Cataract (HP:0000518): A cataract is an opacity or clouding that develops in the crystalline lens of the eye or in its capsule. Evidence: IEA. (OMIM:160900)
- Obsessive-compulsive trait (HP:0008770): The presence of one or more obsessive-compulsive personality traits. Obsessions refer to persistent intrusive thoughts, and compulsions to intrusive behaviors, which the affected person experiences as involuntary, senseless, or repugnant. Evidence: IEA. (OMIM:160900)
- Testicular atrophy (HP:0000029): Wasting (atrophy) of the testicle (the male gonad) manifested by a decrease in size and potentially by a loss of fertility. Evidence: IEA. (OMIM:160900)
- Facial diplegia (HP:0001349): Facial diplegia refers to bilateral facial palsy (bilateral facial palsy is much rarer than unilateral facial palsy). Evidence: IEA. (OMIM:160900)
- Decreased fetal movement (HP:0001558): An abnormal reduction in quantity or strength of fetal movements. Evidence: IEA. (OMIM:160900)
- Feeding difficulties in infancy (HP:0008872): Impaired feeding performance of an infant as manifested by difficulties such as weak and ineffective sucking, brief bursts of sucking, and falling asleep during sucking. There may be difficulties with chewing or maintaining attention. Evidence: PCS. (OMIM:160900)
- Atrial flutter (HP:0004749): A type of atrial arrhythmia characterized by atrial rates of between 240 and 400 beats per minute and some degree of atrioventricular node conduction block. Typically, the ventricular rate is half the atrial rate. In the EKG; atrial flutter waves are observed as sawtooth-like atrial activity. Pathophysiologically, atrial flutter is a form of atrial reentry in which there is a premature electrical impulse creates a self-propagating circuit. Evidence: PCS. Frequency: 4/11. (PMID:15557517)
- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: TAS. (OMIM:160900)
- Hypogonadism (HP:0000135): A decreased functionality of the gonad. Evidence: IEA. (OMIM:160900)
- Autosomal dominant inheritance (HP:0000006): A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele. Evidence: IEA. (OMIM:160900)
- Intellectual disability (HP:0001249): The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence. Evidence: IEA. (OMIM:160900)
These phenotypes are associated with the disease myotonic dystrophy type 1 (OMIM:160900).