GLI3-related Pallister-Hall syndrome (GLI3-PHS) is characterized by a spectrum of anomalies ranging from polydactyly, asymptomatic bifid epiglottis, and hypothalamic hamartoma at the mild end to laryngotracheal cleft with neonatal lethality at the severe end. Individuals with mild GLI3-PHS may be incorrectly diagnosed as having isolated postaxial polydactyly type A. Individuals with GLI3-PHS can have pituitary insufficiency and may die as neonates from undiagnosed and untreated adrenal insufficiency.

Borjeson-Forssman-Lehmann syndrome (BFLS) is an uncommon X-linked intellectual developmental disorder that evolves with age. Clinical manifestations in males are quite variable, with the most consistent features being initial hypotonia, mild to moderate impaired intellectual development, large fleshy ears, underdeveloped genitalia, gynecomastia, truncal obesity, tapering fingers, and shortening of the fourth and fifth toes. Heterozygous females may have a milder similar clinical phenotype, which can include hypothyroidism; however, many carrier females appear unaffected (summary by Crawford et al., 2006).

Keutel syndrome (KTLS) is an autosomal recessive disorder characterized by multiple peripheral pulmonary stenoses, brachytelephalangy, inner ear deafness, and abnormal cartilage ossification or calcification (summary by Khosroshahi et al., 2014).

Familial anonychia/onychodystrophy with hypoplasia or absence of distal phalanges (ODP) is a rare disorder characterized by onychodystrophy, anonychia, brachydactyly of the fifth finger, and digitalization of the thumbs, with absence or hypoplasia of the distal phalanges of the hands and feet. Generally the nails of the first to third digits are progressively deformed with total anonychia in the last 2 digits and in all toes (summary by Genzer-Nir et al., 2010). A syndrome has been described in which affected females display juvenile hypertrophy of the breast (JHB; 113670) in association with ODP, whereas males have only ODP (mammary-digital-nail syndrome; 613689).

Hyperphosphatasia with impaired intellectual development syndrome-3 (HPMRS3) is an autosomal recessive disorder characterized by severe intellectual disability, hypotonia with poor motor development, poor speech, and increased serum alkaline phosphatase (summary by Hansen et al., 2013). However, the severity of the disorder can also vary to include more mild intellectual impairment (Krawitz et al., 2013). The disorder is caused by a defect in glycosylphosphatidylinositol (GPI) biosynthesis. For a discussion of genetic heterogeneity of HPMRS, see HPMRS1 (239300). For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293).

Hyperphosphatasia with impaired intellectual development syndrome-2 (HPMRS2) is an autosomal recessive disorder characterized by moderately to severely delayed psychomotor development, facial dysmorphism, brachytelephalangy, and increased serum alkaline phosphatase (hyperphosphatasia). Some patients may have additional features, such as cardiac septal defects or seizures (summary by Krawitz et al., 2012). The disorder is caused by a defect in glycosylphosphatidylinositol (GPI) biosynthesis. For a discussion of genetic heterogeneity of hyperphosphatasia with impaired intellectual development syndrome, see HPMRS1 (239300). For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293).

Hyperphosphatasia with impaired intellectual development syndrome-4 (HPMRS4) is an autosomal recessive neurologic disorder characterized by severely delayed psychomotor development, impaired intellectual development, lack of speech acquisition, seizures, and dysmorphic facial features. Laboratory studies show increased serum alkaline phosphatase (summary by Howard et al., 2014). The disorder is caused by a defect in glycosylphosphatidylinositol (GPI) biosynthesis. For a discussion of genetic heterogeneity of HPMRS, see HPMRS1 (239300). For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293).

Cerebellofaciodental syndrome is an autosomal recessive neurodevelopmental disorder characterized by delayed development, intellectual disability, abnormal facial and dental findings, and cerebellar hypoplasia (summary by Borck et al., 2015).

Hyperphosphatasia with impaired intellectual development syndrome-6 (HPMRS6) is an autosomal recessive multisystem disorder characterized by global developmental delay, dysmorphic features, seizures, and congenital cataracts. Severity is variable, and the disorder may show a range of phenotypic and biochemical abnormalities, including increased serum alkaline phosphatase levels (summary by Ilkovski et al., 2015). The disorder is caused by a defect in glycosylphosphatidylinositol (GPI) biosynthesis. For a discussion of genetic heterogeneity of HPMRS, see HPMRS1 (239300). For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293).

Ritscher-Schinzel syndrome-3 (RTSC3) is characterized by craniocerebellocardiac anomalies and severe postnatal growth restriction, as well as complicated skeletal malformations, including vertebral body hypoossification, sternal aplasia, and chondrodysplasia punctata. Other features include developmental delay, ocular anomalies, periventricular nodular heterotopia, and proteinuria (Kato et al., 2020). For a discussion of genetic heterogeneity of Ritscher-Schinzel syndrome, see RTSC1 (220210).