- Epicanthus (HP:0000286): A fold of skin starting above the medial aspect of the upper eyelid and arching downward to cover, pass in front of and lateral to the medial canthus. Evidence: PCS. Frequency: 2/3. (PMID:29909962)
- Failure to thrive in infancy (HP:0001531). Evidence: PCS. Frequency: 3/3. (PMID:29909962)
- Seizure (HP:0001250): A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Evidence: PCS. Frequency: 3/3. Onset: Neonatal onset (HP:0003623). (PMID:29909962)
- Elevated urinary mevalonate lactone level (HP:6000675): The amount of mevalonate lactone in the urine, normalized for urine concentration, is above the upper limit of normal. Evidence: PCS. Frequency: 2/2. (PMID:29909962)
- Elevated circulating methylsuccinic acid concentration (HP:0033146): Increased concentration of methylsuccinic acid in the blood circulation. Evidence: PCS. (PMID:29909962)
- Dry skin (HP:0000958): Skin characterized by the lack of natural or normal moisture. Evidence: PCS. Frequency: 3/3. (PMID:29909962)
- Irritability (HP:0000737): An emotional state characterized by negative feelings of heightened frustration, annoyance, or feeling upset, often triggered by internal factors (e.g., fatigue, hunger, unfulfilled desires) or external factors (e.g., social or environmental challenges). Irritability may be unpredictable, and is accompanied by a lowered threshold for emotional reactivity and observable features (speech, facial expressions, or psychomotor activity). Evidence: PCS. Frequency: 3/3. (PMID:29909962)
- Cerebral visual impairment (HP:0100704): A form of loss of vision caused by damage to the visual cortex rather than a defect in the eye. Evidence: PCS. Frequency: 3/3. (PMID:29909962)
- Bicuspid aortic valve (HP:0001647): The presence of an aortic valve with two instead of the normal three cusps (flaps). Bicuspid aortic valvue is a malformation of a commissure (small space between the attachment of each cusp to the aortic wall) and the adjacent parts of the two corresponding cusps forming a raphe (the fused area of the two underdeveloped cusps turning into a malformed commissure between both cusps; the raphe is a fibrous ridge that extends from the commissure to the free edge of the two underdeveloped, conjoint cusps). Evidence: PCS. Frequency: 1/3. (PMID:29909962)
- Abnormality of hair pigmentation (HP:0009887): An abnormality of hair pigmentation (color). Evidence: PCS. (PMID:29909962)
- Retrognathia (HP:0000278): An abnormality in which the mandible is mislocalised posteriorly. Evidence: PCS. Frequency: 2/3. (PMID:29909962)
- Constipation (HP:0002019): Infrequent or difficult evacuation of feces. Evidence: PCS. Frequency: 3/3. (PMID:29909962)
- Posteriorly rotated ears (HP:0000358): A type of abnormal location of the ears in which the position of the ears is characterized by posterior rotation (the superior part of the ears is rotated towards the back of the head, and the inferior part of the ears towards the front). Evidence: PCS. Frequency: 1/3. (PMID:29909962)
- Cutaneous photosensitivity (HP:0000992): An increased sensitivity of the skin to light. Photosensitivity may result in a rash upon exposure to the sun (which is known as photodermatosis). Photosensitivity can be diagnosed by phototests in which light is shone on small areas of skin. Evidence: PCS. Frequency: 3/3. (PMID:29909962)
- Decreased circulating LDL-C concentration (HP:0003563): The concentration of low-density lipoprotein cholesterol in the blood circulation is below the lower limit of normal. Evidence: PCS. Frequency: 3/3. (PMID:29909962)
- Hypoplasia of the corpus callosum (HP:0002079): Underdevelopment of the corpus callosum. Evidence: PCS. Frequency: 2/3. (PMID:29909962)
- Hypocholesterolemia (HP:0003146): An decreased concentration of cholesterol in the blood. Evidence: PCS. Frequency: 3/3. (PMID:29909962)
- Elevated urine mesaconic acid level (HP:6000465): The amount of mesaconic acid in the urine, normalized for urine concentration, is above the upper limit of normal. Evidence: PCS. Frequency: 1/1. (PMID:29909962)
- Slender long bone (HP:0003100): Reduced diameter of a long bone. Evidence: PCS. Frequency: 2/3. (PMID:29909962)
- Elevated methylhex-dienedioic level by MRS (HP:6000147): An increase in the level of 3-methylhex-2,4-dienedioic acid or 3-methylhex-3,4-dienedioic acid in the brain identified by magnetic resonance spectroscopy (MRS). Evidence: PCS. (PMID:32027475)
- Elevated urine 3-methyladipic acid level (HP:6000466): The amount of 3-methyladipic acid in the urine, normalized for urine concentration, is above the upper limit of normal. Evidence: PCS. Frequency: 1/1. (PMID:29909962)
- 2-3 toe syndactyly (HP:0004691): Syndactyly with fusion of toes two and three. Evidence: PCS. Frequency: 2/3. (PMID:29909962)
- Profound global developmental delay (HP:0012736): A profound delay in the achievement of motor or mental milestones in the domains of development of a child. Evidence: PCS. Frequency: 3/3. (PMID:29909962)
- Depressed nasal bridge (HP:0005280): Posterior positioning of the nasal root in relation to the overall facial profile for age. Evidence: PCS. Frequency: 2/3. (PMID:29909962)
- Gastrostomy tube feeding in infancy (HP:0011471): Feeding problem necessitating gastrostomy tube feeding. Evidence: PCS. Frequency: 3/3. (PMID:29909962)
- Increased circulating farnesol concentration (HP:0033083): An elevated level of farnesol in the blood circulation. Evidence: PCS. Frequency: 2/2. (PMID:29909962)
- Optic nerve hypoplasia (HP:0000609): Underdevelopment of the optic nerve. Evidence: PCS. Frequency: 2/3. (PMID:29909962)
- Knee flexion contracture (HP:0006380): A type of knee joint contracture in which the knee is in a fixed bent (flexed) configuration such that it cannot be straightened actively or passively. Evidence: PCS. Frequency: 2/3. (PMID:29909962)
- Autosomal recessive inheritance (HP:0000007): 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 individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele). Evidence: PCS. (PMID:29909962)
- Macrotia (HP:0000400): Median longitudinal ear length greater than two standard deviations above the mean and median ear width greater than two standard deviations above the mean (objective); or, apparent increase in length and width of the pinna (subjective). Evidence: PCS. Frequency: 2/3. (PMID:29909962)
- Intrauterine growth retardation (HP:0001511): An abnormal restriction of fetal growth with fetal weight below the tenth percentile for gestational age. Evidence: PCS. Frequency: 3/3. Onset: Antenatal onset (HP:0030674). (PMID:29909962)
- Bilateral cryptorchidism (HP:0008689): Absence of both testes from the scrotum owing to failure of the testis or testes to descend through the inguinal canal to the scrotum. Evidence: PCS. Frequency: 1/2. (PMID:29909962)
- Hypospadias (HP:0000047): Abnormal position of urethral meatus on the ventral penile shaft (underside) characterized by displacement of the urethral meatus from the tip of the glans penis to the ventral surface of the penis, scrotum, or perineum. Evidence: PCS. Frequency: 1/2. (PMID:29909962)
- Elbow flexion contracture (HP:0002987): An elbow contracture that limits the ability of the elbow joint to be extended (straightened), meaning that the elbow is fixed in an flexed (bent) position. Evidence: PCS. Frequency: 1/3. (PMID:29909962)
- Polymicrogyria (HP:0002126): Polymicrogyria is a congenital malformation of the cerebral cortex characterized by abnormal cortical layering (lamination) and an excessive number of small gyri (folds). Evidence: PCS. Frequency: 1/3. (PMID:29909962)
- Micrognathia (HP:0000347): Developmental hypoplasia of the mandible. Evidence: PCS. Frequency: 2/3. (PMID:29909962)
- Low-set ears (HP:0000369): Upper insertion of the ear to the scalp below an imaginary horizontal line drawn between the inner canthi of the eye and extending posteriorly to the ear. Evidence: PCS. Frequency: 1/3. (PMID:29909962)
These phenotypes are associated with the disease squalene synthase deficiency (OMIM:618156).