Amelogenesis imperfecta

Gene: NECTIN4

Green List (high evidence)

Comment on list classification: There are at least 6 unrelated individuals with biallelic NECTIN4 variants and Ectodermal dysplasia-syndactyly syndrome 1. All affected individuals presented with dental abnormalities, including enamel hypoplasia, tooth agenesis, and peg-shaped, widely-spaced teeth. Based on available evidence, this gene should be promoted to Green for Amelogenesis imperfecta at the next GMS update.

Created: 7 Nov 2025, 2:13 p.m. | Last Modified: 7 Nov 2025, 2:37 p.m.

Panel Version: 4.12

PMID: 20691405 Brancati et al. 2010
Family A - 4 affected siblings, Algerian origins, first-cousin parents; c.851G>A (p.Arg284Gln), homozygous; phenotype: progressive alopecia, pili torti, widely-spaced peg-shaped teeth, syndactyly fingers 2-3/3-4, toes 2-3/4-5. Study shows that the variants results in exon 4 skipping, leading to a p.(Phe244CysfsX22) change (premature stop codon).
Family B - 2 sibs born to nonconsanguineous Italian parents; phenotype: alopecia, pili torti, abnormal teeth, cutaneous syndactyly. Compound heterozygous c.554C>T (p.Thr185Met) + c.906delT (p.Pro304HisfsX2). 50% reduced mRNA expression in cultured epidermal keratinocytes of patient II:1 (family B).

PMID: 21346770, Jelani et al. 2011
10 affected individuals across a consanguineous Pakistani pedigree. Used microsatellite markers to assign disease locus. Affected individuals homozygous for c.635C>G; p.Pro212Arg - LOD score 5.05. Phenotype: sparse hair, conical teeth with enamel hypoplasia, nail dystrophy, palmoplantar keratoderma, bilateral syndactyly fingers 3-4 and toes 2-3.

PMID: 34067522 Rotunno et al., 2021
Reports 5yo female patient; c.1150delC (p.Gln384ArgfsTer7), homozygous; phenotype: Brittle hair, sparse eyebrows/eyelashes, toenail dystrophy, mild palmoplantar keratoderma. Her teeth were widely spaced and conical, with small crowns and enamel hypoplasia + agenesis of 4 wisdom teeth.

PMID: 37829154 Ali et al., 2023
Consanguineous Kashmiri Family. All 4 affected individuals harboured a homozygous nonsense variant NM 030916: c.181C > T, p.(Gln61Ter). Method: WES. Hypotrichosis, syndactyly fingers 3-4 and toes 2-3, discolored nails, upper lip cleft; conical teeth, with enamel ridges, and pits, widely spaced.

PMID: 37183149 Hajra et al., 2023
Large consanguineous Pakistani family. Only NECTIN4 coding region sequenced. All 15 affected individuals were homozygous for c.163C>T; p.(Arg55*). Phenotype: sparse hair; hypoplastic nails with thick flat discoloured nail plates; peg-shaped, conical, and widely spaced teeth with enamel hypoplasia; proximal cutaneous syndactyly of fingers and toes; skin was dry and scaly with hyperkeratosis and palmoplantar keratoderma.

NECTIN4, previously known as PVRL4, is linked to Ectodermal dysplasia-syndactyly syndrome 1, 613573 (OMIM, accessed 7th Nov 2025).

Created: 7 Nov 2025, 2:02 p.m. | Last Modified: 7 Nov 2025, 2:10 p.m.

Panel Version: 4.9

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Ectodermal dysplasia-syndactyly syndrome 1, OMIM:613573; ectodermal dysplasia-syndactyly syndrome 1, MONDO:0024565; amelogenesis imperfecta, MONDO:0019507

Publications

• 20691405
• 21346770
• 34067522
• 37183149
• 37829154

Green List (high evidence)

Evidence from literature is that loss of function variants in NECTIN4 lead to a syndromic phenotype which includes "enamel hypoplasia" a term often used when amelogenesis imperfecta occurs with other symptoms.

PMID:34067522 describes ectodermal dysplasia-syndactyly syndrome 1 (EDSS1) characterized by cutaneous syndactyly of the toes and fingers and abnormalities of the hair and teeth, variably associated with nail dystrophy and palmoplantar keratoderma (PPK). EDSS1 is caused by biallelic mutations in the NECTIN4. Nine other EDSS1 cases have been described prior to this report. 5.5-year-old female child affected with EDSS1 due to the novel homozygous frameshift mutation c.1150delC (p.Gln384ArgfsTer7) in NECTIN4. The patient presents brittle scalp hair, sparse eyebrows and eyelashes, widely spaced conical teeth and dental agenesis, as well as toenail dystrophy and mild PPK. She has minimal proximal syndactyly limited to toes 2–3, which makes the phenotype of our patient peculiar as the overt involvement of both fingers and toes is typical of EDSS1. All previously described mutations are located in the nectin-4 extracellular portion, whereas p.Gln384ArgfsTer7 occurs within the cytoplasmic domain of the protein. This mutation is predicted to affect the interaction with afadin, suggesting that impaired afadin activation is sufficient to determine EDSS1.

PMID 37183149 reported a large Pakistani consanguineous family, the affected individuals presented the classical EDSS1 clinical features including sparse hair, hypoplastic nails with thick flat discolored nail plates, peg-shaped, conical, and widely spaced teeth with enamel hypoplasia, proximal cutaneous syndactyly of fingers and toes. NECTIN4 novel nonsense variant [c.163C>T; p.(Arg55*)]. Most likely Nectin-4 function will be lost.
Sources: Literature

Created: 16 Jul 2025, 8:47 a.m.

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
syndactyly of the toes and fingers; hair abnormalities; variable dental genesis; enamel hypoplasia (amelogenesis imperfecta?); variable nail dystrophy; variable palmoplantar keratoderma, hyperkeratosis, reduced sweating

Publications

• PMID: 34067522
• 37183149