Entry - #615637 - INTELLECTUAL DEVELOPMENTAL DISORDER, AUTOSOMAL RECESSIVE 41; MRT41 - OMIM
# 615637

INTELLECTUAL DEVELOPMENTAL DISORDER, AUTOSOMAL RECESSIVE 41; MRT41


Alternative titles; symbols

MENTAL RETARDATION, AUTOSOMAL RECESSIVE 41


Phenotype-Gene Relationships

Location Phenotype Phenotype
MIM number
Inheritance Phenotype
mapping key
Gene/Locus Gene/Locus
MIM number
19q13.32 Intellectual developmental disorder, autosomal recessive 41 615637 AR 3 KPTN 615620
Clinical Synopsis
 
Phenotypic Series
 

INHERITANCE
- Autosomal recessive
HEAD & NECK
Head
- Macrocephaly (+3-5 SD)
Face
- Frontal bossing
- Prominent chin
- Retrognathia
Ears
- Small ears
Eyes
- Hooded eyelids
- Downslanting palpebral fissures
- Sunken eyes
Nose
- Broad nasal tip
SKELETAL
Skull
- Scaphocephaly
Hands
- Fifth finger clinodactyly
MUSCLE, SOFT TISSUES
- Hypotonia
NEUROLOGIC
Central Nervous System
- Delayed psychomotor development
- Impaired intellectual development, mild to severe
- Speech deficits
- Seizures (in some patients)
- Intractable epilepsy (in 1 patient)
Behavioral Psychiatric Manifestations
- Anxiety
- Repetitive speech
- Stereotyped behaviors
MISCELLANEOUS
- Onset at birth
- Originally reported in the Ohio Amish Anabaptist community
MOLECULAR BASIS
- Caused by mutation in the kaptin gene (KPTN, 615620.0001)
Intellectual developmental disorder, autosomal recessive - PS249500 - 71 Entries
Location Phenotype Inheritance Phenotype
mapping key
Phenotype
MIM number
Gene/Locus Gene/Locus
MIM number
1p36.32 Intellectual developmental disorder, autosomal recessive 77 AR 3 619988 CEP104 616690
1p34.1 Intellectual developmental disorder, autosomal recessive 12 AR 3 611090 ST3GAL3 606494
1p21.1-p13.3 Intellectual developmental disorder, autosomal recessive 4 AR 2 611107 MRT4 611107
1p13.3 Intellectual developmental disorder, autosomal recessive 60 AR 3 617432 TAF13 600774
1p13.3 Intellectual developmental disorder, autosomal recessive 48 AR 3 616269 SLC6A17 610299
1q24.3 Glycosylphosphatidylinositol biosynthesis defect 16 AR 3 617816 PIGC 601730
1q31.1 ?Intellectual developmental disorder, autosomal recessive 79 AR 3 620393 TPR 189940
1q32.1 Intellectual developmental disorder, autosomal recessive 65 AR 3 618109 KDM5B 605393
1q43 Intellectual developmental disorder, autosomal recessive 47 AR 3 616193 FMN2 606373
2q11.2 ?Intellectual developmental disorder, autosomal recessive 52 AR 3 616887 LMAN2L 609552
2q22.1 Intellectual developmental disorder, autosomal recessive 51 AR 3 616739 HNMT 605238
2q31.1 Intellectual developmental disorder, autosomal recessive 72 AR 3 618665 METTL5 618628
3p26.2 Intellectual developmental disorder, autosomal recessive 2 AR 3 607417 CRBN 609262
3q12.3 Intellectual developmental disorder, autosomal recessive 69 AR 3 618383 ZBTB11 618181
3q25.32 Intellectual developmental disorder, autosomal recessive 70 AR 3 618402 RSRC1 613352
3q26.2-q26.31 Intellectual developmental disorder, autosomal recessive 54 AR 3 617028 TNIK 610005
4q12-q13.1 Intellectual developmental disorder, autosomal recessive 31 AR 2 614329 MRT31 614329
4q26 Intellectual developmental disorder, autosomal recessive 1 AR 3 249500 PRSS12 606709
4q27-q28.2 Intellectual developmental disorder, autosomal recessive 29 AR 2 614333 MRT29 614333
5p15.31 Intellectual developmental disorder, autosomal recessive 5 AR 3 611091 NSUN2 610916
5q32 ?Intellectual developmental disorder, autosomal recessive 63 AR 3 618095 CAMK2A 114078
5q33.1 Intellectual developmental disorder, autosomal recessive 46 AR 3 616116 NDST1 600853
5q33.2 ?Intellectual developmental disorder, autosomal recessive 76 AR 3 619931 GRIA1 138248
6p12.2-q12 Intellectual developmental disorder, autosomal recessive 24 AR 2 614345 MRT24 614345
6q12-q15 Intellectual developmental disorder, autosomal recessive 30 AR 2 614342 MRT30 614342
6q16.3 Intellectual developmental disorder, autosomal recessive 81 AR 3 620700 ASCC3 614217
6q16.3 Intellectual developmental disorder, autosomal recessive 6 AR 3 611092 GRIK2 138244
6q23.2 Intellectual developmental disorder, autosomal recessive 18, with or without epilepsy AR 3 614249 MED23 605042
6q26-q27 Intellectual developmental disorder, autosomal recessive 28 AR 2 614347 MRT28 614347
7q34 Intellectual developmental disorder, autosomal recessive 80, with variant lissencephaly AR 3 620653 CASP2 600639
8p22 Intellectual developmental disorder, autosomal recessive 7 AR 3 611093 TUSC3 601385
8p12 Intellectual developmental disorder, autosomal recessive 39 AR 3 615541 TTI2 614426
8q21.13 Intellectual developmental disorder, autosomal recessive 59 AR 3 617323 IMPA1 602064
8q24.12 Intellectual developmental disorder, autosomal recessive 40 AR 3 615599 TAF2 604912
8q24.3 Intellectual developmental disorder, autosomal recessive 13 AR 3 613192 TRAPPC9 611966
9p23-p13.3 Intellectual developmental disorder, autosomal recessive 16 AR 2 614208 MRT16 614208
9p13.3 Intellectual developmental disorder, autosomal recessive 61 AR 3 617773 RUSC2 611053
9q34.3 Rafiq syndrome AR 3 614202 MAN1B1 604346
10p12.31 Intellectual developmental disorder, autosomal recessive 82 AR 3 620779 NSUN6 617199
10q21.2 Intellectual developmental disorder, autosomal recessive 37 AR 3 615493 ANK3 600465
10q26.12 Intellectual developmental disorder, autosomal recessive 78 AR 3 620237 WDR11 606417
11p15.5 Intellectual developmental disorder, autosomal recessive 75, with neuropsychiatric features and variant lissencephaly AR 3 619827 PIDD1 605247
11p15.4 Intellectual developmental disorder, autosomal recessive 67 AR 3 618295 EIF3F 603914
11p13-q14.1 Intellectual developmental disorder, autosomal recessive 23 AR 2 614344 MRT23 614344
11q22.3 Intellectual developmental disorder, autosomal recessive 71 AR 3 618504 ALKBH8 613306
12p13.32 Intellectual developmental disorder, autosomal recessive 66 AR 3 618221 C12orf4 616082
12q13.11-q15 Intellectual developmental disorder, autosomal recessive 25 AR 2 614346 MRT25 614346
12q14.2 Intellectual developmental disorder, autosomal recessive 83 AR 3 621100 KICS2 617420
12q22 Intellectual developmental disorder, autosomal recessive 34, with variant lissencephaly AR 3 614499 CRADD 603454
12q23.3 Intellectual developmental disorder, autosomal recessive 43 AR 3 615817 WASHC4 615748
14q11.2-q12 Intellectual developmental disorder, autosomal recessive 9/26 AR 2 611095 MRT9 611095
14q31.3 Intellectual developmental disorder, autosomal recessive 56 AR 3 617125 ZC3H14 613279
15q13.1 Intellectual developmental disorder, autosomal recessive 38 AR 3 615516 HERC2 605837
15q24.1 ?Intellectual developmental disorder, autosomal recessive 50 AR 3 616460 EDC3 609842
15q24.3 Intellectual developmental disorder, autosomal recessive 64 AR 3 618103 LINGO1 609791
15q26.3 Intellectual developmental disorder, autosomal recessive 27 AR 3 614340 LINS1 610350
16p12.2-q12.1 Intellectual developmental disorder, autosomal recessive 10/20 AR 2 611096 MRT10 611096
16q24.2 ?Intellectual developmental disorder, autosomal recessive 45 AR 3 615979 FBXO31 609102
17p13.2-p13.1 Intellectual developmental disorder, autosomal recessive 33 AR 2 614341 MRT33 614341
17q21.31-q22 Intellectual developmental disorder, autosomal recessive 35 AR 2 615162 MRT35 615162
17q25.1 Intellectual developmental disorder, autosomal recessive 44 AR 3 615942 METTL23 615262
18q12.2 Intellectual developmental disorder, autosomal recessive 58 AR 3 617270 ELP2 616054
19p13.3 Intellectual developmental disorder, autosomal recessive 74 AR 3 617169 APC2 612034
19p13.3 Neurodevelopmental disorder with brain abnormalities, poor growth, and dysmorphic facies AR 3 615286 ADAT3 615302
19p13.13 Intellectual developmental disorder, autosomal recessive 68 AR 3 618302 TRMT1 611669
19p13.12 Intellectual developmental disorder, autosomal recessive 3 AR 3 608443 CC2D1A 610055
19p13.12 Intellectual developmental disorder, autosomal recessive 14 AR 3 614020 TECR 610057
19q13.2-q13.3 Intellectual developmental disorder, autosomal recessive 11 AR 2 611097 MRT11 611097
19q13.32 Intellectual developmental disorder, autosomal recessive 41 AR 3 615637 KPTN 615620
19q13.42 Intellectual developmental disorder, autosomal recessive 57 AR 3 617188 MBOAT7 606048
20p11.23 Intellectual developmental disorder, autosomal recessive 73 AR 3 619717 NAA20 610833

TEXT

A number sign (#) is used with this entry because of evidence that autosomal recessive intellectual disorder-41 (MRT41) is caused by homozygous or compound heterozygous mutation in the KPTN gene (615620) on chromosome 19q13.


Description

Autosomal recessive intellectual developmental disorder-41 (MRT41) is characterized by macrocephaly and global developmental delay. Some patients have seizures (Baple et al., 2014).


Clinical Features

Baple et al. (2014) reported 9 individuals from 4 nuclear Anabaptist Amish families from Ohio with an autosomal recessive intellectual developmental disorder. The patients had global developmental delay, mildly delayed walking, high levels of anxiety, stereotyped behavior, and repetitive speech. Dysmorphic features included macrocephaly (+3 to +5.4 SD) with frontal bossing, craniosynostosis, scaphocephaly, broad nasal bridge, hooded eyelids with small, downslanting palpebral fissures, and a prominent chin. Three patients had a seizure disorder, and 6 had childhood hypotonia. Less common features included fifth finger clinodactyly, recurrent pneumonia, and hepatosplenomegaly. Neuroimaging was unremarkable.

Pajusalu et al. (2015) reported 2 adult Estonian sibs with MRT41 apparent since early childhood. Both had normal early development, but presented with speech delay and intellectual disability at school age, resulting in special schooling. The brother had more severe behavioral abnormalities, including anxiety, autistic features, stereotypic movements, and some self-aggression. Both had macrocephaly (+4-4.5 SD), prominent forehead, high palate, and microretrognathia. The brother had a few isolated seizures in childhood, whereas the sister had no seizures. EEG in both patients showed generalized slowing of background activity. As adults, they lived in a special home for the intellectually disabled; they had basic self-care and communication skills.

Thiffault et al. (2020) reported a 9-year-old patient with MRT41 who presented with status epilepticus, macrocephaly, intractable epilepsy, autism, severe developmental delay, hypotonia, and hypoglycemia. He had dysmorphic features including frontal bossing, downslanting palpebral fissures, and small ears. He had a history of hepatosplenomegaly and hypoglycemic episodes at 5 months of age.

Pacio Miguez et al. (2020) reported 2 sisters, aged 7 and 3 years, with MRT41. The older sister presented at 3 years of age with speech and motor delay. At 7 years of age she had macrocephaly and expressive language impairment. The younger sister had progressive macrocephaly and speech delay at 3 years and 6 months of age. In both sibs, comprehensive language was less affected than expressive language, and they both had delayed closure of the anterior fontanel. A brain MRI in the younger sister showed nonspecific supratentorial leukoencephalopathy, and signal hyperintensity in the dentate nuclei. Neither sib had seizures.


Inheritance

The transmission pattern of MRT41 in the family reported by Baple et al. (2014) was consistent with autosomal recessive inheritance.


Molecular Genetics

In 4 affected individuals from 2 consanguineous Amish families with autosomal recessive impaired intellectual development and macrocephaly, Baple et al. (2014) identified a homozygous truncating mutation in the KPTN gene (S259X; 615620.0001). The mutation was found using a combination of homozygosity mapping and whole-exome sequencing. Five affected individuals from 2 additional consanguineous Amish families were compound heterozygous for S259X and an in-frame duplication in the KPTN gene (615620.0002). All 4 families were determined to be distantly related, consistent with 2 founder mutations in this community. Transfection of the mutations into COS-7 cells showed that the mutant proteins did not localize like wildtype proteins to F-actin-rich lamellipodia, but rather accumulated at irregular perinuclear sites, suggesting a loss of normal activity. The truncated protein showed a more pronounced tendency to form such accumulations compared to the duplication mutation. Baple et al. (2014) suggested that the mutations resulted in a loss of KPTN function, which could lead to impairment of the neuronal actin cytoskeleton that is required for dendritic arborization or spine formation during neurogenesis.

In 2 Estonian sibs with MRT41, Pajusalu et al. (2015) identified a homozygous 1-bp duplication (c.665dupA; 615620.0003) in the KPTN gene, predicted to result in a frameshift (Gln222fs). The mutation, which was found by whole-exome sequencing and confirmed by Sanger sequencing, segregated with the disorder in the family. Functional studies of the variant and studies of patient cells were not performed. The findings indicated that the disorder is not restricted to the Amish population.

In a 9-year-old Caucasian boy with MRT41, Thiffault et al. (2020) identified compound heterozygous mutations in the KPTN gene, a previously identified in-frame duplication (615620.0002) and a splice site mutation (615620.0004). The mutations were found by whole-genome sequencing and confirmed by Sanger sequencing. The splice site mutation but not the duplication was inherited from the mother, suggesting that the variants were in trans.

In 2 Spanish sibs with MRT41, Pacio Miguez et al. (2020) identified a homozygous 2-bp duplication in the KPTN gene (615620.0005). No information regarding segregation was provided.


REFERENCES

  1. Baple, E. L., Maroofian, R., Chioza, B. A., Izadi, M., Cross, H. E., Al-Turki, S., Barwick, K., Skrzypiec, A., Pawlak, R., Wagner, K., Coblentz, R., Zainy, T., Patton, M. A., Mansour, S., Rich, P., Qualmann, B., Hurles, M. E., Kessels, M. M., Crosby, A. H. Mutations in KPTN cause macrocephaly, neurodevelopmental delay, and seizures. Am. J. Hum. Genet. 94: 87-94, 2014. [PubMed: 24239382, images, related citations] [Full Text]

  2. Pacio Miguez, M., Santos-Simarro, F., Garcia-Minaur, S., Velazquez Fragua, R., Del Pozo, A., Solis, M., Jimenez Rodriguez, C., Rufo-Rabadan, V., Fernandez, V. E., Rueda, I., Gomez Del Pozo, M. V., Gallego, N., Lapunzina, P., Palomares-Bralo, M. Pathogenic variants in KPTN, a rare cause of macrocephaly and intellectual disability. (Letter) Am. J. Med. Genet. 182A: 2222-2225, 2020. [PubMed: 32808430, related citations] [Full Text]

  3. Pajusalu, S., Reimand, T., Ounap, K. Novel homozygous mutation in KPTN gene causing a familial intellectual disability-macrocephaly syndrome. Am. J. Med. Genet. 167A: 1913-1915, 2015. [PubMed: 25847626, related citations] [Full Text]

  4. Thiffault, I., Atherton, A., Heese, B. A., T Abdelmoity, A., Pawar, K., Farrow, E., Zellmer, L., Miller, N., Soden, S., Saunders, C. Pathogenic variants in KPTN gene identified by clinical whole-genome sequencing. Cold Spring Harbor Molec. Case Stud. 6: a003970, 2020. [PubMed: 32358097, related citations] [Full Text]


Hilary J. Vernon - updated : 04/07/2023
Cassandra L. Kniffin - updated : 03/23/2018
Creation Date:
Cassandra L. Kniffin : 2/11/2014
carol : 01/16/2024
carol : 04/07/2023
carol : 04/06/2022
alopez : 03/30/2018
ckniffin : 03/23/2018
carol : 02/17/2014
mcolton : 2/17/2014
ckniffin : 2/11/2014

# 615637

INTELLECTUAL DEVELOPMENTAL DISORDER, AUTOSOMAL RECESSIVE 41; MRT41


Alternative titles; symbols

MENTAL RETARDATION, AUTOSOMAL RECESSIVE 41


ORPHA: 397612;   DO: 0081206;  


Phenotype-Gene Relationships

Location Phenotype Phenotype
MIM number
Inheritance Phenotype
mapping key
Gene/Locus Gene/Locus
MIM number
19q13.32 Intellectual developmental disorder, autosomal recessive 41 615637 Autosomal recessive 3 KPTN 615620

TEXT

A number sign (#) is used with this entry because of evidence that autosomal recessive intellectual disorder-41 (MRT41) is caused by homozygous or compound heterozygous mutation in the KPTN gene (615620) on chromosome 19q13.


Description

Autosomal recessive intellectual developmental disorder-41 (MRT41) is characterized by macrocephaly and global developmental delay. Some patients have seizures (Baple et al., 2014).


Clinical Features

Baple et al. (2014) reported 9 individuals from 4 nuclear Anabaptist Amish families from Ohio with an autosomal recessive intellectual developmental disorder. The patients had global developmental delay, mildly delayed walking, high levels of anxiety, stereotyped behavior, and repetitive speech. Dysmorphic features included macrocephaly (+3 to +5.4 SD) with frontal bossing, craniosynostosis, scaphocephaly, broad nasal bridge, hooded eyelids with small, downslanting palpebral fissures, and a prominent chin. Three patients had a seizure disorder, and 6 had childhood hypotonia. Less common features included fifth finger clinodactyly, recurrent pneumonia, and hepatosplenomegaly. Neuroimaging was unremarkable.

Pajusalu et al. (2015) reported 2 adult Estonian sibs with MRT41 apparent since early childhood. Both had normal early development, but presented with speech delay and intellectual disability at school age, resulting in special schooling. The brother had more severe behavioral abnormalities, including anxiety, autistic features, stereotypic movements, and some self-aggression. Both had macrocephaly (+4-4.5 SD), prominent forehead, high palate, and microretrognathia. The brother had a few isolated seizures in childhood, whereas the sister had no seizures. EEG in both patients showed generalized slowing of background activity. As adults, they lived in a special home for the intellectually disabled; they had basic self-care and communication skills.

Thiffault et al. (2020) reported a 9-year-old patient with MRT41 who presented with status epilepticus, macrocephaly, intractable epilepsy, autism, severe developmental delay, hypotonia, and hypoglycemia. He had dysmorphic features including frontal bossing, downslanting palpebral fissures, and small ears. He had a history of hepatosplenomegaly and hypoglycemic episodes at 5 months of age.

Pacio Miguez et al. (2020) reported 2 sisters, aged 7 and 3 years, with MRT41. The older sister presented at 3 years of age with speech and motor delay. At 7 years of age she had macrocephaly and expressive language impairment. The younger sister had progressive macrocephaly and speech delay at 3 years and 6 months of age. In both sibs, comprehensive language was less affected than expressive language, and they both had delayed closure of the anterior fontanel. A brain MRI in the younger sister showed nonspecific supratentorial leukoencephalopathy, and signal hyperintensity in the dentate nuclei. Neither sib had seizures.


Inheritance

The transmission pattern of MRT41 in the family reported by Baple et al. (2014) was consistent with autosomal recessive inheritance.


Molecular Genetics

In 4 affected individuals from 2 consanguineous Amish families with autosomal recessive impaired intellectual development and macrocephaly, Baple et al. (2014) identified a homozygous truncating mutation in the KPTN gene (S259X; 615620.0001). The mutation was found using a combination of homozygosity mapping and whole-exome sequencing. Five affected individuals from 2 additional consanguineous Amish families were compound heterozygous for S259X and an in-frame duplication in the KPTN gene (615620.0002). All 4 families were determined to be distantly related, consistent with 2 founder mutations in this community. Transfection of the mutations into COS-7 cells showed that the mutant proteins did not localize like wildtype proteins to F-actin-rich lamellipodia, but rather accumulated at irregular perinuclear sites, suggesting a loss of normal activity. The truncated protein showed a more pronounced tendency to form such accumulations compared to the duplication mutation. Baple et al. (2014) suggested that the mutations resulted in a loss of KPTN function, which could lead to impairment of the neuronal actin cytoskeleton that is required for dendritic arborization or spine formation during neurogenesis.

In 2 Estonian sibs with MRT41, Pajusalu et al. (2015) identified a homozygous 1-bp duplication (c.665dupA; 615620.0003) in the KPTN gene, predicted to result in a frameshift (Gln222fs). The mutation, which was found by whole-exome sequencing and confirmed by Sanger sequencing, segregated with the disorder in the family. Functional studies of the variant and studies of patient cells were not performed. The findings indicated that the disorder is not restricted to the Amish population.

In a 9-year-old Caucasian boy with MRT41, Thiffault et al. (2020) identified compound heterozygous mutations in the KPTN gene, a previously identified in-frame duplication (615620.0002) and a splice site mutation (615620.0004). The mutations were found by whole-genome sequencing and confirmed by Sanger sequencing. The splice site mutation but not the duplication was inherited from the mother, suggesting that the variants were in trans.

In 2 Spanish sibs with MRT41, Pacio Miguez et al. (2020) identified a homozygous 2-bp duplication in the KPTN gene (615620.0005). No information regarding segregation was provided.


REFERENCES

  1. Baple, E. L., Maroofian, R., Chioza, B. A., Izadi, M., Cross, H. E., Al-Turki, S., Barwick, K., Skrzypiec, A., Pawlak, R., Wagner, K., Coblentz, R., Zainy, T., Patton, M. A., Mansour, S., Rich, P., Qualmann, B., Hurles, M. E., Kessels, M. M., Crosby, A. H. Mutations in KPTN cause macrocephaly, neurodevelopmental delay, and seizures. Am. J. Hum. Genet. 94: 87-94, 2014. [PubMed: 24239382] [Full Text: https://doi.org/10.1016/j.ajhg.2013.10.001]

  2. Pacio Miguez, M., Santos-Simarro, F., Garcia-Minaur, S., Velazquez Fragua, R., Del Pozo, A., Solis, M., Jimenez Rodriguez, C., Rufo-Rabadan, V., Fernandez, V. E., Rueda, I., Gomez Del Pozo, M. V., Gallego, N., Lapunzina, P., Palomares-Bralo, M. Pathogenic variants in KPTN, a rare cause of macrocephaly and intellectual disability. (Letter) Am. J. Med. Genet. 182A: 2222-2225, 2020. [PubMed: 32808430] [Full Text: https://doi.org/10.1002/ajmg.a.61778]

  3. Pajusalu, S., Reimand, T., Ounap, K. Novel homozygous mutation in KPTN gene causing a familial intellectual disability-macrocephaly syndrome. Am. J. Med. Genet. 167A: 1913-1915, 2015. [PubMed: 25847626] [Full Text: https://doi.org/10.1002/ajmg.a.37105]

  4. Thiffault, I., Atherton, A., Heese, B. A., T Abdelmoity, A., Pawar, K., Farrow, E., Zellmer, L., Miller, N., Soden, S., Saunders, C. Pathogenic variants in KPTN gene identified by clinical whole-genome sequencing. Cold Spring Harbor Molec. Case Stud. 6: a003970, 2020. [PubMed: 32358097] [Full Text: https://doi.org/10.1101/mcs.a003970]


Contributors:
Hilary J. Vernon - updated : 04/07/2023
Cassandra L. Kniffin - updated : 03/23/2018

Creation Date:
Cassandra L. Kniffin : 2/11/2014

Edit History:
carol : 01/16/2024
carol : 04/07/2023
carol : 04/06/2022
alopez : 03/30/2018
ckniffin : 03/23/2018
carol : 02/17/2014
mcolton : 2/17/2014
ckniffin : 2/11/2014