- Hypertonia (HP:0001276): A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move. Evidence: IEA. (OMIM:267700)
- Hemiplegia (HP:0002301): Paralysis (complete loss of muscle function) in the arm, leg, and in some cases the face on one side of the body. Evidence: IEA. (OMIM:267700)
- Decreased circulating HDL-C concentration (HP:0003233): The concentration of high-density lipoprotein cholesterol in the blood circulation is below the lower limit of normal. Evidence: TAS. (OMIM:267700)
- 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: IEA. (OMIM:267700)
- Increased total bilirubin (HP:0003573): Increased concentration of total (conjugated and unconjugated) bilirubin in the blood. Evidence: IEA. (OMIM:267700)
- 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:267700)
- Hypoproteinemia (HP:0003075): A decreased concentration of protein in the blood. Evidence: IEA. (OMIM:267700)
- Ataxia (HP:0001251): Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). Evidence: IEA. (OMIM:267700)
- Hepatomegaly (HP:0002240): Abnormally increased size of the liver. Evidence: IEA. (OMIM:267700)
- Infectious encephalitis (HP:0002383): A disorder of the brain caused by an infectious agent that presents with fever, headache, and an altered level of consciousness. There may also be focal or multifocal neurologic deficits, and focal or generalized seizure activity. Evidence: IEA. (OMIM:267700)
- Hypoalbuminemia (HP:0003073): The concentration of albumin in the blood circulation is below the lower limit of normal. Evidence: IEA. (OMIM:267700)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: TAS. (OMIM:267700)
- CSF pleocytosis (HP:0012229): An increased white blood cell count in the cerebrospinal fluid. Evidence: TAS. (OMIM:267700)
- Hemophagocytosis (HP:0012156): Phagocytosis by macrophages of erythrocytes, leukocytes, platelets, and their precursors in bone marrow and other tissues. Evidence: TAS. (OMIM:267700)
- Prolonged prothrombin time (HP:0008151): Increased time to coagulation in the prothrombin time test, which is a measure of the extrinsic pathway of coagulation. The results of the prothrombin time test are often expressed in terms of the International normalized ratio (INR), which is calculated as a ratio of the patient's prothrombin time (PT) to a control PT standardized for the potency of the thromboplastin reagent developed by the World Health Organization (WHO) using the formula: INR is equal to Patient PT divided by Control PT. Evidence: TAS. (OMIM:267700)
- Failure to thrive (HP:0001508): Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm. Evidence: IEA. (OMIM:267700)
- 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: IEA. (OMIM:267700)
- Anemia (HP:0001903): A reduction in erythrocytes volume or hemoglobin concentration. Evidence: IEA. (OMIM:267700)
- Lymphadenopathy (HP:0002716): Enlargement (swelling) of a lymph node. Evidence: IEA. (OMIM:267700)
- Increased intracranial pressure (HP:0002516): An increase of the pressure inside the cranium (skull) and thereby in the brain tissue and cerebrospinal fluid. Evidence: IEA. (OMIM:267700)
- Jaundice (HP:0000952): Yellow pigmentation of the skin due to bilirubin, which in turn is the result of increased bilirubin concentration in the bloodstream. Evidence: IEA. (OMIM:267700)
- Splenomegaly (HP:0001744): Abnormal increased size of the spleen. Evidence: IEA. (OMIM:267700)
- Prolonged partial thromboplastin time (HP:0003645): Increased time to coagulation in the partial thromboplastin time (PTT) test, a measure of the intrinsic and common coagulation pathways. Phospholipid, and activator, and calcium are mixed into an anticoagulated plasma sample, and the time is measured until a thrombus forms. Evidence: IEA. (OMIM:267700)
- Meningitis (HP:0001287): Inflammation of the meninges. Evidence: IEA. (OMIM:267700)
- Hypertriglyceridemia (HP:0002155): An abnormal increase in the level of triglycerides in the blood. Evidence: IEA. (OMIM:267700)
- Decreased total leukocyte count (HP:0001882): An abnormal decreased number of leukocytes in the blood. Evidence: IEA. (OMIM:267700)
- Global developmental delay (HP:0001263): A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age. Evidence: TAS. (OMIM:267700)
- Elevated circulating LDL-C concentration (HP:0003141): The concentration of low-density lipoprotein cholesterol in the blood circulation is above the upper limit of normal. Evidence: TAS. (OMIM:267700)
- Elevated circulating VLDL-C concentration (HP:0003362): The concentration of very-low-density lipoprotein cholesterol in the blood circulation is above the upper limit of normal. Evidence: TAS. (OMIM:267700)
- Hypofibrinogenemia (HP:0011900): Decreased concentration of fibrinogen in the blood. Evidence: TAS. (OMIM:267700)
- Increased circulating ferritin concentration (HP:0003281): Increased concentration of ferritin in the blood circulation. Evidence: IEA. (OMIM:267700)
- Generalized edema (HP:0007430): Generalized abnormal accumulation of fluid beneath the skin, or in one or more cavities of the body. Evidence: IEA. (OMIM:267700)
- Hyponatremia (HP:0002902): The concentration of sodium in the blood circulation is below the lower limit of normal. Evidence: IEA. (OMIM:267700)
- 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: IEA. (OMIM:267700)
- Increased CSF protein concentration (HP:0002922): Increased concentration of protein in the cerebrospinal fluid. Evidence: IEA. (OMIM:267700)
- Thrombocytopenia (HP:0001873): A reduction in the number of circulating thrombocytes. Evidence: IEA. (OMIM:267700)
- Tetraplegia (HP:0002445): Paralysis of all four limbs, and trunk of the body below the level of an associated injury to the spinal cord. The etiology of quadriplegia is similar to that of paraplegia except that the lesion is in the cervical spinal cord rather than in the thoracic or lumbar segments of the spinal cord. Evidence: IEA. (OMIM:267700)
- Coma (HP:0001259): The complete absence of wakefulness and consciousness, which is evident through a lack of response to any form of external stimuli. Evidence: TAS. (OMIM:267700)
These phenotypes are associated with the disease familial hemophagocytic lymphohistiocytosis type 1 (OMIM:267700).