Isolated growth hormone deficiency type IA (IGHD1A) is an autosomal recessive disorder characterized by severe growth failure (SDS less than -4.5) by 6 months of age, undetectable growth hormone (GH) concentrations, and a tendency to develop antibodies despite an initial good response to rhGH treatment (summary by Alatzoglou et al., 2014). Genetic Heterogeneity of Isolated Growth Hormone Deficiency See IGHD1B (617281) and IGHD2 (173100), both caused by mutation in the GH1 gene; IGHD3 (307200), caused by mutation in the BTK gene (300300); and IGHD4 (618157), caused by mutation in the GHRHR gene (139191). Isolated growth hormone deficiency-5 (IGHD5) has been reclassified as combined pituitary hormone deficiency-7 (CPHD7; 618160).

PROP1-related combined pituitary hormone deficiency (CPHD) is associated with deficiencies of: growth hormone (GH); thyroid-stimulating hormone (TSH); the two gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH); prolactin (PrL); and occasionally adrenocorticotropic hormone (ACTH). At birth, in contrast to individuals with congenital CPHD of other etiologies, neonates with PROP1-related CPHD lack perinatal signs of hypopituitarism. Mean birth weights and lengths are usually within the normal range and neonatal hypoglycemia and prolonged neonatal jaundice are not prevalent findings. Most affected individuals are ascertained because of short stature during childhood. Although TSH deficiency can present shortly after birth, TSH deficiency usually occurs with or after the onset of GH deficiency. Hypothyroidism is usually mild. FSH and LH deficiencies are typically identified at the age of onset of puberty. Affected individuals can have absent or delayed and incomplete secondary sexual development with infertility. Untreated males usually have a small penis and small testes. Some females experience menarche but subsequently require hormone replacement therapy. ACTH deficiency is less common and, when present, usually occurs in adolescence or adulthood. Neuroimaging of hypothalamic-pituitary region usually demonstrates a hypoplastic or normal anterior pituitary lobe and a normal posterior pituitary lobe.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

PNPLA6 disorders span a phenotypic continuum characterized by variable combinations of cerebellar ataxia; upper motor neuron involvement manifesting as spasticity and/or brisk reflexes; chorioretinal dystrophy associated with variable degrees of reduced visual function; and hypogonadotropic hypogonadism (delayed puberty and lack of secondary sex characteristics). The hypogonadotropic hypogonadism occurs either in isolation or as part of anterior hypopituitarism (growth hormone, thyroid hormone, or gonadotropin deficiencies). Common but less frequent features are peripheral neuropathy (usually of axonal type manifesting as reduced distal reflexes, diminished vibratory sensation, and/or distal muscle wasting); hair anomalies (long eyelashes, bushy eyebrows, or scalp alopecia); short stature; and impaired cognitive functioning (learning disabilities in children; deficits in attention, visuospatial abilities, and recall in adults). Some of these features can occur in distinct clusters on the phenotypic continuum: Boucher-Neuhäuser syndrome (cerebellar ataxia, chorioretinal dystrophy, and hypogonadotropic hypogonadism); Gordon Holmes syndrome (cerebellar ataxia, hypogonadotropic hypogonadism, and – to a variable degree – brisk reflexes); Oliver-McFarlane syndrome (trichomegaly, chorioretinal dystrophy, short stature, intellectual disability, and hypopituitarism); Laurence-Moon syndrome; and spastic paraplegia type 39 (SPG39) (upper motor neuron involvement, peripheral neuropathy, and sometimes reduced cognitive functioning and/or cerebellar ataxia).

RHYNS syndrome is characterized by gaze palsy, retinitis pigmentosa, sensorineural hearing loss, hypopituitarism, nephronophthisis, and mild skeletal dysplasia (Di Rocco et al., 1997).

Isolated growth hormone deficiency type IB (IGH1B) is an autosomal recessive disorder characterized by low but detectable levels of GH, short stature (more than 2 SD below the mean for age and sex), delayed bone age, and a good response to rhGH treatment without antibody formation (summary by Alatzoglou et al., 2014). For general phenotypic information and a discussion of genetic heterogeneity of IGHD, see 262400.

Combined pituitary hormone deficiency (CPHD) in man denotes impaired production of growth hormone (GH; 139250) and one or more of the other 5 anterior pituitary hormones. Mutations of the POU1F1 gene in the human and Pit1 in the mouse are responsible for pleiotropic deficiencies of GH, prolactin (PRL; 176760), and thyroid-stimulating hormone (TSH; see 188540), while the production of adrenocorticotrophic hormone (ACTH; see 176830), luteinizing hormone (LH; 152780), and follicle-stimulating hormone (FSH; 136530) are preserved (Wu et al., 1998). Some patients exhibit only GH deficiency, although approximately 50% of isolated GH deficiency progresses to CPHD (Gergics et al., 2021). In infancy severe growth deficiency from birth as well as distinctive facial features with prominent forehead, marked midfacial hypoplasia with depressed nasal bridge, deep-set eyes, and a short nose with anteverted nostrils and hypoplastic pituitary gland by MRI examination can be seen (Aarskog et al., 1997). Some cases present with severe mental retardation along with short stature (Radovick et al., 1992). Reviews Voss and Rosenfeld (1992) reviewed the development and differentiation of the 5 pituitary cell types: galactotropes, gonadotropes, corticotropes, thyrotropes, and somatotropes. As indicated by the mutations in PIT1 described later, combined pituitary hormone deficiency can have either autosomal dominant or autosomal recessive inheritance, depending on the part of the PIT1 molecule affected by the mutation. Some mutations have a dominant-negative effect. Genetic Heterogeneity of Combined Pituitary Hormone Deficiency CPHD2 (262600), associated with hypogonadism, is caused by mutation in the PROP1 gene (601538). CPHD3 (221750), which is associated with rigid cervical spine and variable sensorineural deafness, is caused by mutation in the LHX3 gene (600577). CPHD4 (262700) is caused by mutation in the LHX4 gene (602146). CPHD5 (see septooptic dysplasia, 182230) is caused by mutation in the HESX1 gene (601802). CPHD6 (613986) is caused by mutation in the OTX2 gene (600037). CPHD7 (618160) is caused by mutation in the RNPC3 gene (618016). CPHD8 (620303) is caused by mutation in the ROBO1 gene (602430).

Any combined pituitary hormone deficiencies, genetic form in which the cause of the disease is a mutation in the OTX2 gene.

This multisystem disorder is characterized by moyamoya disease, short stature, hypergonadotropic hypogonadism, and facial dysmorphism. Other variable features include dilated cardiomyopathy, premature graying of the hair, and early-onset cataracts. Moyamoya disease is a progressive cerebrovascular disorder characterized by stenosis or occlusion of the internal carotid arteries and the main branches, leading to the development of small collateral vessels (moyamoya vessels) at the base of the brain. Affected individuals can develop acute neurologic events due to stroke-like episodes (summary by Miskinyte et al., 2011). For a general phenotypic description and a discussion of genetic heterogeneity of moyamoya disease, see MYMY1 (252350).

A rare genetic epidermal disorder with characteristics of congenital erythroderma with severe psoriasiform dermatitis, ichthyosis, severe palmoplantar keratoderma, yellow keratosis on the hands and feet, elevated immunoglobulin E, multiple food allergies, and metabolic wasting. Other variable features may include hypotrichosis, nail dystrophy, recurrent infections, mild global developmental delay, eosinophilia, nystagmus, growth impairment and cardiac defects.

A rare mitochondrial oxidative phosphorylation disorder with decreased respiratory complex I and IV enzyme activity. Characteristics of this disease hypotonia, global developmental delay, neonatal onset of progressive pectus carinatum without other skeletal abnormalities, poor growth, sensorineural hearing loss, dysmorphic features and brain abnormalities such as cerebral atrophy, quadriventricular dilatation and thin corpus callosum posteriorly.

Combined pituitary hormone deficiency-8 (CPHD8) is an autosomal dominant disorder characterized by deficiency of one or more of the pituitary hormones. Affected individuals have short stature due to growth hormone (GH; 139250) deficiency with variable deficiencies of other pituitary hormones, including TSH (see 188540), ACTH, and LH/FSH (see 118850). Posterior pituitary deficiency leading to central diabetes insipidus is rare (Bashamboo et al., 2017). Many patients are diagnosed with 'pituitary stalk interruption syndrome' (PSIS), which is characterized by a thin or absent pituitary stalk, absent or ectopic posterior pituitary, and hypoplasia of the anterior pituitary demonstrated on brain imaging, although this classic triad may be incomplete. Brauner et al. (2020) noted the complex phenotypic and genetic heterogeneity of PSIS, and concluded that it is a feature of genetic disorders or syndromes rather than a specific clinical entity. For a discussion of genetic heterogeneity of combined pituitary hormone deficiency, see CPHD1 (613038).

Diabetes, deafness, developmental delay, and short stature syndrome (DDDS) is characterized by childhood-onset autoantibody-negative diabetes mellitus and bilateral sensorineural deafness, as well as short stature, microcephaly, and developmental delay (Montaser et al., 2021).

Thrombocytopenia-11 with multiple congenital anomalies and dysmorphic facies (THC11) is a syndromic disorder characterized by dysmorphic facial features, multiple congenital anomalies that may involve the heart, brain, genitourinary, endocrine, and/or skeletal systems, chronic and persistent thrombocytopenia, sometimes with leukopenia or anemia, poor growth with microcephaly, hypotonia, and mildly impaired intellectual development or learning disabilities. The disorder results from constitutive activation of the RAS signaling pathway and can be considered a RASopathy (Niemann et al., 2020; Miller et al., 2022). For a discussion of genetic heterogeneity of thrombocytopenia, see 313900.