Thrombocytopenia absent radius (TAR) syndrome is characterized by bilateral absence of the radii with the presence of both thumbs, and thrombocytopenia that is generally transient. Thrombocytopenia may be congenital or may develop within the first few weeks to months of life; in general, thrombocytopenic episodes decrease with age. Cow's milk allergy is common and can be associated with exacerbation of thrombocytopenia. Other anomalies of the skeleton (upper and lower limbs, ribs, and vertebrae), heart, and genitourinary system (renal anomalies and agenesis of uterus, cervix, and upper part of the vagina) can occur.

Basel-Vanagaite-Smirin-Yosef syndrome is an autosomal recessive multiple congenital anomaly disorder characterized by severely delayed psychomotor development resulting in mental retardation, as well as variable eye, brain, cardiac, and palatal abnormalities (summary by Basel-Vanagaite et al., 2015).

Shashi-Pena syndrome is characterized by distinctive facial features accompanied by variable further clinical findings. Facial features may include glabellar nevus simplex, widely spaced and prominent/proptotic eyes with epicanthal folds and ptosis, arched eyebrows, broad nasal tip, and low-set/posteriorly rotated ears. Dental anomalies may include early eruption and loss of teeth as well as small and fragile teeth. Most affected individuals have infantile hypotonia that frequently resolves over time. Macrosomia and macrocephaly are also common. Affected individuals can have variable developmental delay / intellectual disability, ranging from low-average intellectual abilities to severe intellectual disability. They often demonstrate difficulties with attention and aggressive behavior. Affected individuals may have feeding difficulties that require supportive nasogastric or gastrostomy tube feeding, skin findings (capillary malformations, deep palmar creases, hypertrichosis), skeletal anomalies (scoliosis/kyphosis, hypermobility, frequent fractures), congenital heart defects, seizures, hypoglycemia (most typically in infancy, may be due to hyperinsulinism), vision abnormalities (strabismus, amblyopia), conductive hearing loss, sleep apnea, temperature dysregulation, and global volume loss on brain MRI.

CDK13-related disorder, reported in 43 individuals to date, is characterized in all individuals by developmental delay / intellectual disability (DD/ID); nearly all individuals older than age one year display impaired verbal language skills (either absent or restricted speech). Other common findings are recognizable facial features in some individuals, behavioral problems (autism spectrum disorder or autistic traits/stereotypies, attention-deficit/hyperactivity disorder), feeding difficulties in infancy, structural cardiac defects, and seizures.

Al Kaissi syndrome (ALKAS) is an autosomal recessive developmental disorder characterized by growth retardation, spine malformation, particularly of the cervical spine, dysmorphic facial features, and delayed psychomotor development with moderate to severe intellectual disability (summary by Windpassinger et al., 2017).

Rhizomelic skeletal dysplasia with or without Pelger-Huet anomaly (SKPHA) is an autosomal recessive disorder characterized by rhizomelic skeletal dysplasia of variable severity with or without abnormal nuclear shape and chromatin organization in blood granulocytes (Hoffmann et al., 2002; Borovik et al., 2013; Collins et al., 2020). Initial skeletal features may improve with age (Sobreira et al., 2014).

Neurodevelopmental disorder with growth retardation, dysmorphic facies, and corpus callosum abnormalities (NEDGFC) is an autosomal recessive disorder characterized by these cardinal features apparent from infancy. There is phenotypic variability both in disease manifestations and severity. More severely affected individuals are unable to walk independently, are nonverbal, and may have other anomalies, including congenital heart defects, feeding difficulties, or skeletal defects, whereas others show mildly delayed motor and speech acquisition with mild or borderline intellectual disability (summary by von Elsner et al., 2022).