MedGen

Primary pulmonary hypertension-6 (PPH6) is characterized by markedly elevated pulmonary arterial hypertension, associated with reduced oxygen saturation and diffuse ground-glass opacities on chest x-ray. Lung biopsy shows thickening of the alveolar septae and abnormally proliferating capillaries (Postma et al., 2023). For a general phenotypic description and a discussion of genetic heterogeneity of primary pulmonary hypertension, see PPH1 (178600). [from OMIM]

Neurodevelopmental disorder with hyperkinetic movements, seizures, and structural brain abnormalities (NEDMSB) is a severe autosomal recessive disorder characterized by failure to thrive in infancy, global developmental delay, hypotonia, motor abnormalities with inability to walk, involuntary movements, impaired intellectual development, absent speech, seizures, and structural brain abnormalities (Alkhater et al., 2018; Dafsari et al., 2022). [from OMIM]

Ullrich congenital muscular dystrophy-1 (UCMD1) is characterized by generalized muscle weakness and striking hypermobility of distal joints in conjunction with variable contractures of more proximal joints and normal intelligence. Additional findings may include kyphoscoliosis, protruded calcanei, and follicular hyperkeratosis. Some patients manifest at birth and never achieve independent ambulation, whereas others maintain ambulation into adulthood. Progressive scoliosis and deterioration of respiratory function is a typical feature (summary by Kirschner, 2013). For general phenotypic information and a discussion of genetic heterogeneity of Ullrich congenital muscular dystrophy, see UCMD1A (254090). [from OMIM]

Porphyria-associated leukoencephalopathy (LENCEP) is an autosomal recessive disorder characterized by the onset of variable and slowly progressive neurologic abnormalities in childhood or adolescence with survival to late adulthood. Features include spastic paraparesis, cerebellar ataxia, peripheral axonal neuropathy, ocular abnormalities, and leukoencephalopathy affecting the deep cerebral white matter on brain imaging. Some individuals have more severe manifestations, such as optic atrophy with progressive visual loss, loss of ambulation, and mild cognitive decline. Laboratory studies show variably increased plasma and urinary levels of delta-aminolevulinic acid (ALA), porphobilinogen (PBG), and uroporphyrin due to decreased HMBS enzyme activity. The severity of the disorder appears to depend on the particular genotype and the variant effects on HMBS enzymatic activity; intrafamilial variability is often observed. The clinical discrepancies may be particularly apparent in individuals with compound heterozygous HMBS variants that have different effects on enzyme function (Stutterd et al., 2021). [from OMIM]

Thrombocytopenia-12 with or without myopathy (THC12) is an autosomal recessive disorder characterized by congenital thrombocytopenia apparent from infancy or early childhood. Most affected individuals have bleeding episodes, including petechiae, easy bruising, epistaxis, hematomas, menorrhagia, and increased bleeding after trauma or surgery, although rare patients may have thrombocytopenia without bleeding. Platelets are enlarged (macrothrombocytopenia), and there is an increase of circulating immature platelets, consistent with increased production. Patient platelets show hyposialylation due to GNE mutations, which causes increased removal of platelets from the circulation, shortened platelet lifespan, and resultant thrombocytopenia. In contrast to the thrombocytopenia, which is present since birth or early childhood, features of myopathy usually do not develop until the mid-twenties, similar to Nonaka myopathy (summary by Zhen et al., 2014, Izumi et al., 2014; Bottega et al., 2022). For a discussion of genetic heterogeneity of thrombocytopenia, see THC1 (313900). [from OMIM]

Autosomal recessive deafness-123 (DFNB123) is characterized by nonsyndromic bilateral severe to profound hearing impairment, with onset as early as the first decade of life (Schrauwen et al., 2023). [from OMIM]

Congenital erythropoietic porphyria (CEP) is characterized in most individuals by severe cutaneous photosensitivity with blistering and increased friability of the skin over light-exposed areas. Onset in most affected individuals occurs at birth or early infancy. The first manifestation is often pink-to-dark red discoloration of the urine. Hemolytic anemia is common and can range from mild to severe, with some affected individuals requiring chronic blood transfusions. Porphyrin deposition may lead to corneal ulcers and scarring, reddish-brown discoloration of the teeth (erythrodontia), and bone loss and/or expansion of the bone marrow. The phenotypic spectrum, however, is broad and ranges from nonimmune hydrops fetalis in utero to late-onset disease with only mild cutaneous manifestations in adulthood. [from GeneReviews]

Developmental and epileptic encephalopathy-114 (DEE114) is characterized by moderately to severely impaired intellectual development, onset of epilepsy within the first 18 months of life, and a choreiform, dystonic, or dyskinetic movement disorder (Platzer et al., 2022). For general phenotypic information and a discussion of genetic heterogeneity of DEE, see 308350. [from OMIM]

Coloboma is an ocular birth defect resulting from abnormal development of the eye during embryogenesis. It is defined as a congenital defect in any ocular tissue, typically presenting as absent tissue or a gap, at a site consistent with aberrant closure of the optic fissure. Failure of fusion can lead to coloboma of one or multiple regions of the inferior portion of the eye affecting any part of the globe traversed by the fissure, from the iris to the optic nerve, including the ciliary body, retina, and choroid. Coloboma is also frequently associated with small (microphthalmic) or absent (anophthalmic) eyes as part of an interrelated spectrum of developmental eye anomalies, and can affect either one or both eyes (summary by Kelberman et al., 2014). Microphthalmia/coloboma-12 (MCOPCB12) is characterized by inter- and intrafamilial variability. In addition to microphthalmia and coloboma, other ocular anomalies include iris hypoplasia, aphakia or small lens, lens subluxation, congenital cataract, microcornea, and sclerocornea. Some patients also exhibit neurodevelopmental anomalies (Deml et al., 2016; Williamson et al., 2020). For a discussion of genetic heterogeneity of colobomatous microphthalmia, see MCOPCB1 (300345). [from OMIM]

Neurodevelopmental disorder plus optic atrophy (NEDOA) is an autosomal recessive disorder characterized by impaired intellectual development and childhood-onset optic atrophy or ataxia (Brugger et al., 2024). [from OMIM]

Porphyria-related encephalopathy (ENCEP) is an autosomal recessive disorder characterized by the onset of progressive neurologic abnormalities in early infancy. Features include global developmental delay, poor walking or inability to walk, impaired intellectual development, hypotonia, ataxia, dysarthria, spasticity, ocular abnormalities, and peripheral neuropathy. The disease course is usually rapidly progressive and may lead to death in childhood. Laboratory studies show increased plasma and urinary levels of the putatively neurotoxic porphyrin precursors delta-aminolevulinic acid (ALA), porphobilinogen (PBG), and uroporphyrin resulting from deficient HMBS enzymatic activity (Solis et al., 2004). [from OMIM]

Ullrich congenital muscular dystrophy-1 (UCMD1) is characterized by generalized muscle weakness and striking hypermobility of distal joints in conjunction with variable contractures of more proximal joints and normal intelligence. Additional findings may include kyphoscoliosis, protruded calcanei, and follicular hyperkeratosis. Some patients manifest at birth and never achieve independent ambulation, whereas others maintain ambulation into adulthood. Progressive scoliosis and deterioration of respiratory function is a typical feature (summary by Kirschner, 2013). For general phenotypic information and a discussion of genetic heterogeneity of Ullrich congenital muscular dystrophy, see UCMD1A (254090). [from OMIM]

Developmental and epileptic encephalopathy-113 (DEE113) is characterized by severe early-onset recurrent epilepsy, which is worsened by treatment with levetiracetam. Patients develop secondary failure of growth and development (summary by and Huq, 2015 and Al-Maawali et al., 2024). For general phenotypic information and a discussion of genetic heterogeneity of DEE, see 308350. [from OMIM]

Bethlem myopathy-1 (BTHLM1) is a congenital muscular dystrophy characterized by proximal muscle weakness and a combination of distal and proximal flexion joint contractures. The age at onset is highly variable, ranging from infancy to adulthood, and there is intrafamilial variability. Muscle biopsy may show myopathic and dystrophic features; serum creatine kinase is elevated. The progression is slow and ambulation is usually retained into adulthood (summary by Butterfield et al., 2013; Scacheri et al., 2002). For a discussion of genetic heterogeneity of Bethlem myopathy, see BTHLM1A (158810). [from OMIM]

Autosomal recessive intellectual developmental disorder-82 (MRT82) is characterized by global developmental delay with motor and speech delay, variably impaired intellectual development, and behavioral abnormalities (Mattioli et al., 2023). [from OMIM]

Developmental and epileptic encephalopathy-115 (DEE115) is an autosomal recessive disorder characterized by severe developmental delay and epileptic encephalopathy, massive reduction of white matter, hypo-/aplasia of the corpus callosum, neurodevelopmental arrest, and early death (Brugger et al., 2024). For general phenotypic information and a discussion of genetic heterogeneity of DEE, see 308350. [from OMIM]

Familial atrial hypertrophic cardiomyopathy-30 (CMH30) is characterized by atrial arrhythmias, including flutter and fibrillation, atrial structural abnormalities with hypertrophic cardiomyopathy and fibrosis, and hypertension (Baris Feldman et al., 2023). [from OMIM]

Neurodevelopmental disorder with early-onset parkinsonism and behavioral abnormalities (NEDPBA) is an autosomal recessive disorder characterized by delayed developmental milestones apparent in late infancy or early childhood, impaired intellectual development with learning difficulties, and behavioral abnormalities. Motor abnormalities, including parkinsonism and spasticity, usually develop in the third or fourth decades, although earlier onset has been reported. Some patients have seizures. There is inter- and intrafamilial variability (Kuipers et al., 2018; Al-Kasbi et al., 2021). [from OMIM]

Short stature due to GHSR deficiency is a rare, genetic, endocrine growth disease, resulting from growth hormone secretagogue receptor (GHSR) deficiency, characterized by postnatal growth delay that results in short stature (less than -2 SD). The pituitary gland is typically without morphological changes, although anterior pituitary gland hypoplasia has been reported. [from ORDO]