Microcephalic primordial dwarfism, Dauber type is a rare, genetic developmental defect during embryogenesis characterized by severe pre- and postnatal growth retardation, severe microcephaly, severe developmental delay and intelletual disability, severe adult short stature and facial dysmorphism (incl. hypotelorism, small ears, prominent nose). Other reported features include skeletal anomalies (Madelung deformity, clinodactyly, mild lumbar scoliosis, bilateral hip dysplasia) and seizures. Absence of thelarche and menarche is also associated.

X-linked intellectual developmental disorder-98 (XLID98) is a neurodevelopmental disorder characterized by delayed psychomotor development, poor speech, behavioral abnormalities, poor overall growth, dysmorphic facial features, and often early-onset seizures. Some carrier females are unaffected, whereas other females with mutations are affected; males tend to be more severely affected than females. It is believed that the phenotypic variability and disease manifestations in female carriers results from skewed X-inactivation or cellular mosaicism (summary by de Lange et al., 2016).

A rare genetic disease with characteristics of childhood onset of multiple endocrine manifestations in combination with central and peripheral nervous system abnormalities. Reported signs and symptoms include postnatal growth retardation, moderate intellectual disability, hypogonadotropic hypogonadism, insulin-dependent diabetes mellitus, central hypothyroidism, demyelinating sensorimotor polyneuropathy, cerebellar and pyramidal signs. Progressive hearing loss and a hypoplastic pituitary gland have also been described. Brain imaging shows moderate white matter abnormalities.

Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.

Congenital nongoitrous hypothyroidism-8 (CHNG8) is characterized by relatively mild central hypothyroidism, which may be accompanied by hearing loss in some patients (Heinen et al., 2016).

Nongoitrous congenital hypothyroidism-9 (CHNG9) is characterized by a small thyroid gland with low free T4 (FT4) levels and inappropriately normal levels of thyroid-stimulating hormone (TSH) (Heinen et al., 2018).

BDV syndrome (BDVS) is an autosomal recessive disorder characterized by early-onset profound obesity, hyperphagia, and moderately impaired intellectual development accompanied by infantile hypotonia and other endocrine disorders including hypogonadotropic hypogonadism, hypothyroidism, and insulin resistance (summary by Bosch et al., 2021).

Neurooculorenal syndrome (NORS) is an autosomal recessive developmental disorder with highly variable clinical manifestations involving several organ systems. Some affected individuals present in utero with renal agenesis and structural brain abnormalities incompatible with life, whereas others present in infancy with a neurodevelopmental disorder characterized by global developmental delay and dysmorphic facial features that may be associated with congenital anomalies of the kidney and urinary tract (CAKUT). Additional more variable features may include ocular anomalies, most commonly strabismus, congenital heart defects, and pituitary hormone deficiency. Brain imaging usually shows structural midline defects, including dysgenesis of the corpus callosum and hindbrain. There is variation in the severity, manifestations, and expressivity of the phenotype, even within families (Rasmussen et al., 2018; Munch et al., 2022).