| 22q11.2 deletion |
22q11.2 deletion syndrome
| AD | Wide range of highly variable features; major clinical manifestations incl CHD (esp conotruncal malformations), palatal abnormalities, immune deficiency, characteristic facial features, & learning difficulties. | KdVS may be considered in persons who tested negative for deletion of 22q11.2. |
| Deletions, maternal UPD, imprinting errors w/in PWCR 1 | Prader-Willi syndrome (PWS) | See footnote 1. | Severe hypotonia & feeding difficulties in early infancy, followed in later infancy / early childhood by excessive eating & gradual development of morbid obesity (unless eating is externally controlled); DD/ID; distinctive behavioral phenotype (w/temper tantrums, stubbornness, manipulative behavior, & obsessive-compulsive characteristics) | Behavior issues & sleep disturbances are more common in PWS than in KdVS. |
| Disruption of maternally imprinted UBE3A | Angelman syndrome (AS) | See footnote 2. | Severe DD/ID; severe speech impairment; gait ataxia &/or tremulousness of limbs; unique behavior w/apparent happy demeanor incl frequent laughing, smiling, & excitability; microcephaly & seizures are common. | Research shows that prognosis for speech in persons w/KdVS is positive; apraxia resolves, & although dysarthria persists, most children are intelligible by mid-to-late childhood. 3 Speech delay in children w/AS remains far more severe. 4 |
BRAF
KRAS
MAP2K1
MAP2K2
| Cardiofaciocutaneous syndrome (CFC) | AD | Variable findings incl dysmorphic craniofacial features, cardiac issues, skin & hair abnormalities, hypotonia, eye abnormalities, GI dysfunction, seizures, & varying degrees of neurocognitive delay; polyhydramnios is present in vast majority of cases. | Cutaneous features are more common in CFC. CFC & KdVS are further distinguished by differences in facial dysmorphisms. |
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FMR1
| Fragile X syndrome (See FMR1 Disorders.) | XL | In males, DD/ID w/behavioral issues; ASD in 50%-70% of affected persons; characteristic craniofacial features that become more obvious w/age; medical issues incl hypotonia & seizures | Overactivity, impulsivity, & challenging behavior are more common in fragile X syndrome than in KdVS. |
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KAT6B
| KAT6B disorders (incl genitopatellar syndrome & Say-Barber-Biesecker-Young-Simpson variant of Ohdo syndrome) | AD | Broad phenotypic spectrum w/variable expressivity; DD/ID; hypotonia; genital abnormalities; & skeletal abnormalities | Severe ID, immobile mask-like facies, & abnormalities of thyroid structure or function are assoc w/KAT6B disorders. Skeletal issues are more common in KAT6B disorders than in KdVS. |
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KAT8
| KAT8-related intellectual disability (Li-Ghorgani-Weisz-Hubshman syndrome)
(OMIM 618974) | AD | DD/ID, epilepsy, & other developmental anomalies w/variable facial dysmorphisms | Striking facial resemblance between KdVS & KAT8-related ID in some affected persons |
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WAC
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WAC-related intellectual disability
| AD | Variable degrees of DD/ID; behavioral abnormalities incl anxiety, ADHD, &/or ASD are observed in majority of older children & adults. Most infants have significant but nonspecific features at birth such as neonatal hypotonia & feeding issues. | Epilepsy is less common in WAC-related ID than in KdVS. |
