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Monogenic hearing loss v5.33 AP1B1 Achchuthan Shanmugasundram Classified gene: AP1B1 as Amber List (moderate evidence)
Monogenic hearing loss v5.33 AP1B1 Achchuthan Shanmugasundram Gene: ap1b1 has been classified as Amber List (Moderate Evidence).
Monogenic hearing loss v5.32 AP1B1 Achchuthan Shanmugasundram Tag Q3_25_promote_green tag was added to gene: AP1B1.
Monogenic hearing loss v5.32 AP1B1 Achchuthan Shanmugasundram Phenotypes for gene: AP1B1 were changed from Keratitis-ichthyosis-deafness syndrome, autosomal recessive, OMIM:242150; ichthyosiform erythroderma, corneal involvement, and hearing loss, MONDO:0009440 to Keratitis-ichthyosis-deafness syndrome, autosomal recessive, OMIM:242150; KID syndrome, MONDO:0018781
Monogenic hearing loss v5.31 AP1B1 Ida Ertmanska changed review comment from: PMID: 31630791 Alsaif et al., 2019
Family 1: UK and Pakistani origin, consanguineous. Individual II:1, female, presented with congenital ichthyosis, enteropathy, and mild persisting hepatopathy, followed by failure to thrive, global developmental delay, and bilateral severe to profound sensorineural hearing loss.
Similarly affected brother II:2: ichthyosis with erythroderma and diarrhea in the neonatal period. Subsequent problems included enteropathy, severe failure to thrive, global developmental delay, hearing loss, narrow and incomplete cleft of the soft palate, anemia, and respiratory infections. Both homozygous for a gross deletion, (GRCh37/hg19) chr22: 29758984–29815476, which spans AP1B1 and RFPL1 (not yet associated with a disease). Persistently low plasma copper in both siblings.

Family 2: individual II:2 - 4yo boy born to consanguineous healthy Saudi parents. Phenotype: scaly skin, which evolved into generalized ichthyosis with associated palmoplantar hyperkeratosis. He later developed developmental delay, bilateral profound sensorineural deafness, and failure to thrive. Homozygous for AP1B1 NM_001127:c.38-1G>A, p.(Glu14Argfs∗5) - clinical exome.

PMID: 33452671 Vornweg et al., 2021
Female patient with compound het mutations in AP1B1: c.322C>T (p. Arg108Trp) and c.2254delC (p.Leu752Serfs*26). Method: WES + Sanger. Presented with ichthyosiform erythroderma and chronic, severe pruritus from birth; global developmental delay and failure to thrive, thickened plantar surface, bilateral ectropion and partial alopecia; developed bilateral deafness and moderate photophobia. Molecular examination demonstrated complete loss of AP1B1 protein in epidermis and isolated keratinocytes from patient’s skin.

PMID: 33349978 Ito et al., 2021
Report of 2yo Japanese boy. Compound het for AP1B1 c.1852C>T p.Gln618* and 2677C>T p.Gln893*. Method: WES. Presented with ichthyosis, moderate motor & mental retardation, failed the auditory brainstem response test bilatreally. Low calcium and serum copper levels.

PMID: 32969855 Meriç et al., 2021
11mo Turkish girl; consanguineous parents. Homozygous for (AP1B1:NM_001127) c.668T>C, p.Leu223Pro - WES. Presented with ichthyosis and developmental delay. Other symptoms: hearing loss, hepatomegaly, chronic diarrhea, partial alopecia, hyperkeratosis; eye examination showed photophobia and high myopia; diagnosed with mild ID at 7yo. Serum copper within normal limits.

PMID: 35144013 Faghihi et al., 2022
Proband: 6.5yr old boy, consanguineous parents. Homozygous for AP1B1 (NM_001127.4: c.1263C>A, p.Tyr421*) - WES. Presented with developmental delay, keratitis, ichthyosis, and hearing loss. Plasma copper (9 mmol/L) was decreased on several occasions.

AP1B1 is associated with Keratitis-ichthyosis-deafness syndrome, autosomal recessive, 242150 in OMIM (accessed 17th Oct 2025).
This gene was classified as Definitive for AR ichthyosiform erythroderma, corneal involvement, and hearing loss by ClinGen (General Inborn Errors of Metabolism Expert Panel, Aug 2024).
Sources: ClinGen, Literature; to: PMID: 31630791 Alsaif et al., 2019
Family 1: UK and Pakistani origin, consanguineous. Individual II:1, female, presented with congenital ichthyosis, enteropathy, and mild persisting hepatopathy, followed by failure to thrive, global developmental delay, and bilateral severe to profound sensorineural hearing loss.
Similarly affected brother II:2: ichthyosis with erythroderma and diarrhea in the neonatal period. Subsequent problems included enteropathy, severe failure to thrive, global developmental delay, hearing loss, narrow and incomplete cleft of the soft palate, anemia, and respiratory infections. Both homozygous for a gross deletion, (GRCh37/hg19) chr22: 29758984–29815476, which spans AP1B1 and RFPL1 (not yet associated with a disease). Persistently low plasma copper in both siblings.

Family 2: individual II:2 - 4yo boy born to consanguineous healthy Saudi parents. Phenotype: scaly skin, which evolved into generalized ichthyosis with associated palmoplantar hyperkeratosis. He later developed developmental delay, bilateral profound sensorineural deafness, and failure to thrive. Homozygous for AP1B1 NM_001127:c.38-1G>A, p.(Glu14Argfs∗5) - clinical exome.

PMID: 33452671 Vornweg et al., 2021
Female patient with compound het mutations in AP1B1: c.322C>T (p. Arg108Trp) and c.2254delC (p.Leu752Serfs*26). Method: WES + Sanger. Presented with ichthyosiform erythroderma and chronic, severe pruritus from birth; global developmental delay and failure to thrive, thickened plantar surface, bilateral ectropion and partial alopecia; developed bilateral deafness and moderate photophobia. Molecular examination demonstrated complete loss of AP1B1 protein in epidermis and isolated keratinocytes from patient’s skin.

PMID: 33349978 Ito et al., 2021
Report of 2yo Japanese boy. Compound het for AP1B1 c.1852C>T p.Gln618* and 2677C>T p.Gln893*. Method: WES. Presented with ichthyosis, moderate motor & mental retardation, failed the auditory brainstem response test bilatreally. Low calcium and serum copper levels.

PMID: 32969855 Meriç et al., 2021
11mo Turkish girl; consanguineous parents. Homozygous for (AP1B1:NM_001127) c.668T>C, p.Leu223Pro - WES. Presented with ichthyosis and developmental delay. Other symptoms: hearing loss, hepatomegaly, chronic diarrhea, partial alopecia, hyperkeratosis; eye examination showed photophobia and high myopia; diagnosed with mild ID at 7yo. Serum copper within normal limits.

PMID: 35144013 Faghihi et al., 2022
Proband: 6.5yr old boy, consanguineous parents. Homozygous for AP1B1 (NM_001127.4: c.1263C>A, p.Tyr421*) - WES. Presented with developmental delay, keratitis, ichthyosis, and hearing loss. Plasma copper (9 mmol/L) was decreased on several occasions.

AP1B1 is associated with Keratitis-ichthyosis-deafness syndrome, autosomal recessive, 242150 in OMIM (accessed 17th Oct 2025).
This gene was classified as Definitive for AR ichthyosiform erythroderma, corneal involvement, and hearing loss by ClinGen (General Inborn Errors of Metabolism Expert Panel, Aug 2024).
Monogenic hearing loss v5.31 AP1B1 Ida Ertmanska changed review comment from: PMID: 31630791 Alsaif et al., 2019
Family 1: UK and Pakistani origin, consanguineous. Individual II:1, female, presented with congenital ichthyosis, enteropathy, and mild persisting hepatopathy, followed by failure to thrive, global developmental delay, and bilateral severe to profound sensorineural hearing loss.
Similarly affected brother II:2: ichthyosis with erythroderma and diarrhea in the neonatal period. Subsequent problems included enteropathy, severe failure to thrive, global developmental delay, hearing loss, narrow and incomplete cleft of the soft palate, anemia, and respiratory infections. Both homozygous for a gross deletion, (GRCh37/hg19) chr22: 29758984–29815476, which spans AP1B1 and RFPL1 (not yet associated with a disease). Persistently low plasma copper in both siblings.

Family 2: individual II:2 - 4yo boy born to consanguineous healthy Saudi parents. Phenotype: scaly skin, which evolved into generalized ichthyosis with associated palmoplantar hyperkeratosis. He later developed developmental delay, bilateral profound sensorineural deafness, and failure to thrive. Homozygous for AP1B1 NM_001127:c.38-1G>A, p.(Glu14Argfs∗5) - clinical exome.

PMID: 33452671 Vornweg et al., 2021
Female patient with compound het mutations in AP1B1: c.322C>T (p. Arg108Trp) and c.2254delC (p.Leu752Serfs*26). Method: WES + Sanger. Presented with ichthyosiform erythroderma and chronic, severe pruritus from birth; global developmental delay and failure to thrive, thickened plantar surface, bilateral ectropion and partial alopecia; developed bilateral deafness and moderate photophobia. Molecular examination demonstrated complete loss of AP1B1 protein in epidermis and isolated keratinocytes from patient’s skin.

PMID: 33349978 Ito et al., 2021
Report of 2yo Japanese boy. Compound het for AP1B1 c.1852C>T p.Gln618* and 2677C>T p.Gln893*. Method: WES. Presented with ichthyosis, moderate motor & mental retardation, failed the auditory brainstem response test bilatreally. Low calcium and serum copper levels.

PMID: 32969855 Meriç et al., 2021
11mo Turkish girl; consanguineous parents. Homozygous for (AP1B1:NM_001127) c.668T>C, p.Leu223Pro - WES. Presented with ichthyosis and developmental delay. Other symptoms: hearing loss, hepatomegaly, chronic diarrhea, partial alopecia, hyperkeratosis; eye examination showed photophobia and high myopia; diagnosed with mild ID at 7yo. Serum copper within normal limits.

PMID: 35144013 Faghihi et al., 2022
Proband: 6.5yr old boy, consanguineous parents. Homozygous for AP1B1 (NM_001127.4: c.1263C>A, p.Tyr421*) - WES. Presented with developmental delay, keratitis, ichthyosis, and hearing loss. Plasma copper (9 mmol/L) was decreased on several occasions.

AP1B1 is associated with Keratitis-ichthyosis-deafness syndrome, autosomal recessive, 242150 in OMIM (accessed 17th Oct 2025).
Sources: ClinGen, Literature; to: PMID: 31630791 Alsaif et al., 2019
Family 1: UK and Pakistani origin, consanguineous. Individual II:1, female, presented with congenital ichthyosis, enteropathy, and mild persisting hepatopathy, followed by failure to thrive, global developmental delay, and bilateral severe to profound sensorineural hearing loss.
Similarly affected brother II:2: ichthyosis with erythroderma and diarrhea in the neonatal period. Subsequent problems included enteropathy, severe failure to thrive, global developmental delay, hearing loss, narrow and incomplete cleft of the soft palate, anemia, and respiratory infections. Both homozygous for a gross deletion, (GRCh37/hg19) chr22: 29758984–29815476, which spans AP1B1 and RFPL1 (not yet associated with a disease). Persistently low plasma copper in both siblings.

Family 2: individual II:2 - 4yo boy born to consanguineous healthy Saudi parents. Phenotype: scaly skin, which evolved into generalized ichthyosis with associated palmoplantar hyperkeratosis. He later developed developmental delay, bilateral profound sensorineural deafness, and failure to thrive. Homozygous for AP1B1 NM_001127:c.38-1G>A, p.(Glu14Argfs∗5) - clinical exome.

PMID: 33452671 Vornweg et al., 2021
Female patient with compound het mutations in AP1B1: c.322C>T (p. Arg108Trp) and c.2254delC (p.Leu752Serfs*26). Method: WES + Sanger. Presented with ichthyosiform erythroderma and chronic, severe pruritus from birth; global developmental delay and failure to thrive, thickened plantar surface, bilateral ectropion and partial alopecia; developed bilateral deafness and moderate photophobia. Molecular examination demonstrated complete loss of AP1B1 protein in epidermis and isolated keratinocytes from patient’s skin.

PMID: 33349978 Ito et al., 2021
Report of 2yo Japanese boy. Compound het for AP1B1 c.1852C>T p.Gln618* and 2677C>T p.Gln893*. Method: WES. Presented with ichthyosis, moderate motor & mental retardation, failed the auditory brainstem response test bilatreally. Low calcium and serum copper levels.

PMID: 32969855 Meriç et al., 2021
11mo Turkish girl; consanguineous parents. Homozygous for (AP1B1:NM_001127) c.668T>C, p.Leu223Pro - WES. Presented with ichthyosis and developmental delay. Other symptoms: hearing loss, hepatomegaly, chronic diarrhea, partial alopecia, hyperkeratosis; eye examination showed photophobia and high myopia; diagnosed with mild ID at 7yo. Serum copper within normal limits.

PMID: 35144013 Faghihi et al., 2022
Proband: 6.5yr old boy, consanguineous parents. Homozygous for AP1B1 (NM_001127.4: c.1263C>A, p.Tyr421*) - WES. Presented with developmental delay, keratitis, ichthyosis, and hearing loss. Plasma copper (9 mmol/L) was decreased on several occasions.

AP1B1 is associated with Keratitis-ichthyosis-deafness syndrome, autosomal recessive, 242150 in OMIM (accessed 17th Oct 2025).
This gene was classified as Definitive for AR ichthyosiform erythroderma, corneal involvement, and hearing loss by ClinGen (General Inborn Errors of Metabolism Expert Panel, Aug 2024).
Sources: ClinGen, Literature
Monogenic hearing loss v5.31 AP1B1 Ida Ertmanska edited their review of gene: AP1B1: Changed phenotypes to: Keratitis-ichthyosis-deafness syndrome, autosomal recessive, OMIM:242150, KID syndrome, MONDO:0018781
Monogenic hearing loss v5.31 AP1B1 Ida Ertmanska changed review comment from: PMID: 31630791 Alsaif et al., 2019
Family 1: UK and Pakistani origin, consanguineous. Individual II:1, female, presented with congenital ichthyosis, enteropathy, and mild persisting hepatopathy, followed by failure to thrive, global developmental delay, and bilateral severe to profound sensorineural hearing loss.
Similarly affected brother II:2: ichthyosis with erythroderma and diarrhea in the neonatal period. Subsequent problems included enteropathy, severe failure to thrive, global developmental delay, hearing loss, narrow and incomplete cleft of the soft palate, anemia, and respiratory infections. Both homozygous for a gross deletion, (GRCh37/hg19) chr22: 29758984–29815476, which spans AP1B1 and RFPL1 (not yet associated with a disease). Persistently low plasma copper in both siblings.

Family 2: individual II:2 - 4yo boy born to consanguineous healthy Saudi parents. Phenotype: scaly skin, which evolved into generalized ichthyosis with associated palmoplantar hyperkeratosis. He later developed developmental delay, bilateral profound sensorineural deafness, and failure to thrive. Homozygous for AP1B1 NM_001127:c.38-1G>A, p.(Glu14Argfs∗5) - clinical exome.

PMID: 33452671 Vornweg et al., 2021
Female patient with compound het mutations in AP1B1: c.322C>T (p. Arg108Trp) and c.2254delC (p.Leu752Serfs*26). Method: WES + Sanger. Presented with ichthyosiform erythroderma and chronic, severe pruritus from birth; global developmental delay and failure to thrive, thickened plantar surface, bilateral ectropion and partial alopecia; developed bilateral deafness and moderate photophobia.. Molecular examination demonstrated complete loss of AP1B1 protein in epidermis and isolated keratinocytes from patient’s skin.

PMID: 33349978 Ito et al., 2021
Report of 2yo Japanese boy. Compound het for AP1B1 c.1852C>T p.Gln618* and 2677C>T p.Gln893*. Method: WES. Presented with ichthyosis, moderate motor & mental retardation, failed the auditory brainstem response test bilatreally. Low calcium and serum copper levels.

PMID: 32969855 Meriç et al., 2021
11mo Turkish girl; consanguineous parents. Homozygous for (AP1B1:NM_001127) c.668T>C, p.Leu223Pro - WES. Presented with ichthyosis and developmental delay. Other symptoms: hearing loss, hepatomegaly, chronic diarrhea, partial alopecia, hyperkeratosis; eye examination showed photophobia and high myopia; diagnosed with mild ID at 7yo. Serum copper within normal limits.

PMID: 35144013 Faghihi et al., 2022
Proband: 6.5yr old boy, consanguineous parents. Homozygous for AP1B1 (NM_001127.4: c.1263C>A, p.Tyr421*) - WES. Presented with developmental delay, keratitis, ichthyosis, and hearing loss. Plasma copper (9 mmol/L) was decreased on several occasions.

AP1B1 is associated with Keratitis-ichthyosis-deafness syndrome, autosomal recessive, 242150 in OMIM (accessed 17th Oct 2025).
Sources: ClinGen, Literature; to: PMID: 31630791 Alsaif et al., 2019
Family 1: UK and Pakistani origin, consanguineous. Individual II:1, female, presented with congenital ichthyosis, enteropathy, and mild persisting hepatopathy, followed by failure to thrive, global developmental delay, and bilateral severe to profound sensorineural hearing loss.
Similarly affected brother II:2: ichthyosis with erythroderma and diarrhea in the neonatal period. Subsequent problems included enteropathy, severe failure to thrive, global developmental delay, hearing loss, narrow and incomplete cleft of the soft palate, anemia, and respiratory infections. Both homozygous for a gross deletion, (GRCh37/hg19) chr22: 29758984–29815476, which spans AP1B1 and RFPL1 (not yet associated with a disease). Persistently low plasma copper in both siblings.

Family 2: individual II:2 - 4yo boy born to consanguineous healthy Saudi parents. Phenotype: scaly skin, which evolved into generalized ichthyosis with associated palmoplantar hyperkeratosis. He later developed developmental delay, bilateral profound sensorineural deafness, and failure to thrive. Homozygous for AP1B1 NM_001127:c.38-1G>A, p.(Glu14Argfs∗5) - clinical exome.

PMID: 33452671 Vornweg et al., 2021
Female patient with compound het mutations in AP1B1: c.322C>T (p. Arg108Trp) and c.2254delC (p.Leu752Serfs*26). Method: WES + Sanger. Presented with ichthyosiform erythroderma and chronic, severe pruritus from birth; global developmental delay and failure to thrive, thickened plantar surface, bilateral ectropion and partial alopecia; developed bilateral deafness and moderate photophobia. Molecular examination demonstrated complete loss of AP1B1 protein in epidermis and isolated keratinocytes from patient’s skin.

PMID: 33349978 Ito et al., 2021
Report of 2yo Japanese boy. Compound het for AP1B1 c.1852C>T p.Gln618* and 2677C>T p.Gln893*. Method: WES. Presented with ichthyosis, moderate motor & mental retardation, failed the auditory brainstem response test bilatreally. Low calcium and serum copper levels.

PMID: 32969855 Meriç et al., 2021
11mo Turkish girl; consanguineous parents. Homozygous for (AP1B1:NM_001127) c.668T>C, p.Leu223Pro - WES. Presented with ichthyosis and developmental delay. Other symptoms: hearing loss, hepatomegaly, chronic diarrhea, partial alopecia, hyperkeratosis; eye examination showed photophobia and high myopia; diagnosed with mild ID at 7yo. Serum copper within normal limits.

PMID: 35144013 Faghihi et al., 2022
Proband: 6.5yr old boy, consanguineous parents. Homozygous for AP1B1 (NM_001127.4: c.1263C>A, p.Tyr421*) - WES. Presented with developmental delay, keratitis, ichthyosis, and hearing loss. Plasma copper (9 mmol/L) was decreased on several occasions.

AP1B1 is associated with Keratitis-ichthyosis-deafness syndrome, autosomal recessive, 242150 in OMIM (accessed 17th Oct 2025).
Sources: ClinGen, Literature
Monogenic hearing loss v5.31 AP1B1 Ida Ertmanska changed review comment from: PMID: 31630791 Alsaif et al., 2019
Family 1: UK and Pakistani origin, consanguineous. Individual II:1, female, presented with congenital ichthyosis, enteropathy, and mild persisting hepatopathy, followed by failure to thrive, global developmental delay, and bilateral severe to profound sensorineural hearing loss.
Similarly affected brother II:2: ichthyosis with erythroderma and diarrhea in the neonatal period. Subsequent problems included enteropathy, severe failure to thrive, global developmental delay, hearing loss, narrow and incomplete cleft of the soft palate, anemia, and respiratory infections. Both homozygous for a gross deletion, (GRCh37/hg19) chr22: 29758984–29815476, which spans AP1B1 and RFPL1 (not yet associated with a disease). Persistently low plasma copper in both siblings.

Family 2: individual II:2 - 4yo boy born to consanguineous healthy Saudi parents. Phenotype: scaly skin, which evolved into generalized ichthyosis with associated palmoplantar hyperkeratosis. He later developed developmental delay, bilateral profound sensorineural deafness, and failure to thrive. Homozygous for AP1B1 NM_001127:c.38-1G>A, p.(Glu14Argfs∗5) - clinical exome.

PMID: 33452671 Vornweg et al., 2021
Female patient with compound het mutations in AP1B1: c.322C>T (p. Arg108Trp) and c.2254delC (p.Leu752Serfs*26). Method: WES + Sanger. Presented with ichthyosiform erythroderma and chronic, severe pruritus from birth; global developmental delay and failure to thrive, thickened plantar surface, bilateral ectropion and partial alopecia. Molecular examination demonstrated complete loss of AP1B1 protein in epidermis and isolated keratinocytes from patient’s skin.

PMID: 33349978 Ito et al., 2021
Report of 2yo Japanese boy. Compound het for AP1B1 c.1852C>T p.Gln618* and 2677C>T p.Gln893*. Method: WES. Presented with ichthyosis, moderate motor & mental retardation, failed the auditory brainstem response test bilatreally. Low calcium and serum copper levels.

PMID: 32969855 Meriç et al., 2021
11mo Turkish girl; consanguineous parents. Homozygous for (AP1B1:NM_001127) c.668T>C, p.Leu223Pro - WES. Presented with ichthyosis and developmental delay. Other symptoms: hearing loss, hepatomegaly, chronic diarrhea, partial alopecia, hyperkeratosis; eye examination showed photophobia and high myopia; diagnosed with mild ID at 7yo. Serum copper within normal limits.

PMID: 35144013 Faghihi et al., 2022
Proband: 6.5yr old boy, consanguineous parents. Homozygous for AP1B1 (NM_001127.4: c.1263C>A, p.Tyr421*) - WES. Presented with developmental delay, keratitis, ichthyosis, and hearing loss. Plasma copper (9 mmol/L) was decreased on several occasions.

AP1B1 is associated with Keratitis-ichthyosis-deafness syndrome, autosomal recessive, 242150 in OMIM (accessed 17th Oct 2025).
Sources: ClinGen, Literature; to: PMID: 31630791 Alsaif et al., 2019
Family 1: UK and Pakistani origin, consanguineous. Individual II:1, female, presented with congenital ichthyosis, enteropathy, and mild persisting hepatopathy, followed by failure to thrive, global developmental delay, and bilateral severe to profound sensorineural hearing loss.
Similarly affected brother II:2: ichthyosis with erythroderma and diarrhea in the neonatal period. Subsequent problems included enteropathy, severe failure to thrive, global developmental delay, hearing loss, narrow and incomplete cleft of the soft palate, anemia, and respiratory infections. Both homozygous for a gross deletion, (GRCh37/hg19) chr22: 29758984–29815476, which spans AP1B1 and RFPL1 (not yet associated with a disease). Persistently low plasma copper in both siblings.

Family 2: individual II:2 - 4yo boy born to consanguineous healthy Saudi parents. Phenotype: scaly skin, which evolved into generalized ichthyosis with associated palmoplantar hyperkeratosis. He later developed developmental delay, bilateral profound sensorineural deafness, and failure to thrive. Homozygous for AP1B1 NM_001127:c.38-1G>A, p.(Glu14Argfs∗5) - clinical exome.

PMID: 33452671 Vornweg et al., 2021
Female patient with compound het mutations in AP1B1: c.322C>T (p. Arg108Trp) and c.2254delC (p.Leu752Serfs*26). Method: WES + Sanger. Presented with ichthyosiform erythroderma and chronic, severe pruritus from birth; global developmental delay and failure to thrive, thickened plantar surface, bilateral ectropion and partial alopecia; developed bilateral deafness and moderate photophobia.. Molecular examination demonstrated complete loss of AP1B1 protein in epidermis and isolated keratinocytes from patient’s skin.

PMID: 33349978 Ito et al., 2021
Report of 2yo Japanese boy. Compound het for AP1B1 c.1852C>T p.Gln618* and 2677C>T p.Gln893*. Method: WES. Presented with ichthyosis, moderate motor & mental retardation, failed the auditory brainstem response test bilatreally. Low calcium and serum copper levels.

PMID: 32969855 Meriç et al., 2021
11mo Turkish girl; consanguineous parents. Homozygous for (AP1B1:NM_001127) c.668T>C, p.Leu223Pro - WES. Presented with ichthyosis and developmental delay. Other symptoms: hearing loss, hepatomegaly, chronic diarrhea, partial alopecia, hyperkeratosis; eye examination showed photophobia and high myopia; diagnosed with mild ID at 7yo. Serum copper within normal limits.

PMID: 35144013 Faghihi et al., 2022
Proband: 6.5yr old boy, consanguineous parents. Homozygous for AP1B1 (NM_001127.4: c.1263C>A, p.Tyr421*) - WES. Presented with developmental delay, keratitis, ichthyosis, and hearing loss. Plasma copper (9 mmol/L) was decreased on several occasions.

AP1B1 is associated with Keratitis-ichthyosis-deafness syndrome, autosomal recessive, 242150 in OMIM (accessed 17th Oct 2025).
Sources: ClinGen, Literature
Monogenic hearing loss v5.31 AP1B1 Ida Ertmanska commented on gene: AP1B1: Comment on list classification: There are at least 6 unrelated individuals with Keratitis-ichthyosis-deafness syndrome, harbouring biallelic variants in AP1B1. 6/6 individuals developed bilateral sensorineural hearing loss. Hence, this gene fits into the scope of the Monogenic hearing loss panel, and should be promoted to Green at the next GMS update.
Monogenic hearing loss v5.31 AP1B1 Ida Ertmanska gene: AP1B1 was added
gene: AP1B1 was added to Monogenic hearing loss. Sources: ClinGen,Literature
Mode of inheritance for gene: AP1B1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: AP1B1 were set to 31630791; 33452671; 33349978; 32969855; 35144013
Phenotypes for gene: AP1B1 were set to Keratitis-ichthyosis-deafness syndrome, autosomal recessive, OMIM:242150; ichthyosiform erythroderma, corneal involvement, and hearing loss, MONDO:0009440
Review for gene: AP1B1 was set to GREEN
Added comment: PMID: 31630791 Alsaif et al., 2019
Family 1: UK and Pakistani origin, consanguineous. Individual II:1, female, presented with congenital ichthyosis, enteropathy, and mild persisting hepatopathy, followed by failure to thrive, global developmental delay, and bilateral severe to profound sensorineural hearing loss.
Similarly affected brother II:2: ichthyosis with erythroderma and diarrhea in the neonatal period. Subsequent problems included enteropathy, severe failure to thrive, global developmental delay, hearing loss, narrow and incomplete cleft of the soft palate, anemia, and respiratory infections. Both homozygous for a gross deletion, (GRCh37/hg19) chr22: 29758984–29815476, which spans AP1B1 and RFPL1 (not yet associated with a disease). Persistently low plasma copper in both siblings.

Family 2: individual II:2 - 4yo boy born to consanguineous healthy Saudi parents. Phenotype: scaly skin, which evolved into generalized ichthyosis with associated palmoplantar hyperkeratosis. He later developed developmental delay, bilateral profound sensorineural deafness, and failure to thrive. Homozygous for AP1B1 NM_001127:c.38-1G>A, p.(Glu14Argfs∗5) - clinical exome.

PMID: 33452671 Vornweg et al., 2021
Female patient with compound het mutations in AP1B1: c.322C>T (p. Arg108Trp) and c.2254delC (p.Leu752Serfs*26). Method: WES + Sanger. Presented with ichthyosiform erythroderma and chronic, severe pruritus from birth; global developmental delay and failure to thrive, thickened plantar surface, bilateral ectropion and partial alopecia. Molecular examination demonstrated complete loss of AP1B1 protein in epidermis and isolated keratinocytes from patient’s skin.

PMID: 33349978 Ito et al., 2021
Report of 2yo Japanese boy. Compound het for AP1B1 c.1852C>T p.Gln618* and 2677C>T p.Gln893*. Method: WES. Presented with ichthyosis, moderate motor & mental retardation, failed the auditory brainstem response test bilatreally. Low calcium and serum copper levels.

PMID: 32969855 Meriç et al., 2021
11mo Turkish girl; consanguineous parents. Homozygous for (AP1B1:NM_001127) c.668T>C, p.Leu223Pro - WES. Presented with ichthyosis and developmental delay. Other symptoms: hearing loss, hepatomegaly, chronic diarrhea, partial alopecia, hyperkeratosis; eye examination showed photophobia and high myopia; diagnosed with mild ID at 7yo. Serum copper within normal limits.

PMID: 35144013 Faghihi et al., 2022
Proband: 6.5yr old boy, consanguineous parents. Homozygous for AP1B1 (NM_001127.4: c.1263C>A, p.Tyr421*) - WES. Presented with developmental delay, keratitis, ichthyosis, and hearing loss. Plasma copper (9 mmol/L) was decreased on several occasions.

AP1B1 is associated with Keratitis-ichthyosis-deafness syndrome, autosomal recessive, 242150 in OMIM (accessed 17th Oct 2025).
Sources: ClinGen, Literature