Version July 2025
| Disorder | Inheritance and gene | Common ultrasound findings* |
| Monogenic | ||
| Noonan syndrome | Autosomal dominant: Most common genes: PTPN11, BRAF, KRAS, MAP2K1, MRAS, NRAS De novo variant: Less common Autosomal recessive: LZTR1 variants | Elevated nuchal translucency, cystic hygroma, CHD 50 to 80% with pulmonary valve stenosis most common, characteristic facies |
| Smith Lemli Opitz Syndrome | Autosomal recessive: Disorder of cholesterol synthesis: DHCR7 – 96% mutation, 4% deletion | 2/3 syndactyly, microcephaly, hypospadias multiple major malformations |
| Cornelia de Lange Syndrome | Autosomal dominant: New mutation 99% of time; NIPB, SMC1A, HDAC8, SMC3, RAD21 and BRD4 X-linked: HDAC8, SMC1A | Mild to severe FGR, upper limb defects Cardiac septal defects Microcephaly Characteristic facies |
| Fanconi anemia | Autosomal recessive: 25 genes known, FANCA 60 to 70% mutation or deletion Autosomal dominant: RAD51 X-linked: FANCB | Skeletal abnormalities – often radius/thumb GU abnormalities, bone marrow failure, low platelets |
| Achondroplasia | Autosomal dominant: FGFR3 mutation De novo: If normal parents | Rhizomelic short limbs >4 SD below mean, macrocephaly, frontal bossing trident hand |
| Uniparental disomy | ||
| Silver-Russell | De novo: Maternal UPD7 Imprinting defect paternal H/19/IGF2 | Severe early FGR, relative macrocephaly |
| Aneuploidy | ||
| Triploidy (3n = 69) | ||
| (2n from the father and 1n from the mother) Sporadic | Symmetric FGR, 80% structural abnormalities Cystic large placenta, oligohydramnios Risk for GTN 1 to 2% |
| (2n from the mother and 1n from the father) Sporadic | Severe FGR, asymmetric Small placenta, oligohydramnios |
| Trisomy | Extra chromosome 13/18 most common | |
| Trisomy 21 | Shortened long bones | |
| Monosomy | Turner syndrome | Shortened long bones |
| Duplications/deletions | Multiple described – 7 to 9% of fetuses with FGR | Structural abnormalities |
| Confined placental mosaicism | ||
| (Observed for every chromosome except 19) | ||
| Chromosome 16 | Most common | FGR in 43 to 58%: Malformations: 20% Prematurity: 32 to 37%, preeclampsia: 16 to 24% |
CHD: congenital heart disease; FGR: fetal growth restriction; GTN: gestational trophoblastic neoplasia; GU: genitourinary; SD: standard deviation.
* Ultrasound findings depend on gestational age. For example, achondroplasia is often not short limbed until the third trimester. Also, classic findings from the pediatric phenotype may not be visualized in the fetus (eg, typical facies, relative macrocephaly in Russell Silver).
