hypotonia

Al Kaissi Syndrome

Clinical Characteristics
Ocular Features: 

Reported facial dysmorphism features include periocular anomalies of ptosis, hypertelorism, down-slanting lid fissures, and epicanthal folds.  

Systemic Features: 

The phenotype is somewhat variable.  Intrauterine and postnatal growth retardation with hypotonia are common.   Moderate to severe intellectual disability is usually present and speech may be severely delayed.  The forehead is narrow, the nasal tip is broad, the nasal bridge is depressed, and the ears are low-set and posteriorly rotated.   Small hands and sometimes joint laxity are commonly present.  Cervical spine abnormalities including clefting, improper fusion, and segmentation anomalies are common.

Brain MRI may be normal but a small corpus callosum was present in some patients.

Genetics

Homozygous mutations in the CDK10 gene (16q24.3) are responsible for this disorder.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

CDK10 Mutations in Humans and Mice Cause Severe Growth Retardation, Spine Malformations, and Developmental Delays

Windpassinger C, Piard J, Bonnard C, Alfadhel M, Lim S, Bisteau X, Blouin S, Ali NB, Ng AYJ, Lu H, Tohari S, Talib SZA, van Hul N, Caldez MJ, Van Maldergem L, Yigit G, Kayserili H, Youssef SA, Coppola V, de Bruin A, Tessarollo L, Choi H, Rupp V, Roetzer K, Roschger P, Klaushofer K, Altmuller J, Roy S, Venkatesh B, Ganger R, Grill F, Ben Chehida F, Wollnik B, Altunoglu U, Al Kaissi A, Reversade B, Kaldis P. CDK10 Mutations in Humans and Mice Cause Severe Growth Retardation, Spine Malformations, and Developmental Delays. Am J Hum Genet. 2017 Sep 7;101(3):391-403.

PubMed ID: 
28886341

Spastic Ataxia 8, Autosomal Recessive, with Hypomyelinating Leukodystrophy

Clinical Characteristics
Ocular Features: 

Reported ocular signs are limited to abnormal eye movements.  In other forms of spastic ataxia, nystagmus is evident in association with optic atrophy but no fundus examinations are reported in the 3 families with SPAX8.  Hypometric saccades and limited upgaze have also been found in these families.

Systemic Features: 

First signs and symptoms occur sometime in the first 5 years of life and often in the first year.   In 6 of 7 reported patients the presenting sign was nystagmus but one individual with reported onset of disease at age 5 years presented with ataxia.  Cerebellar signs, both truncal and limb, are usually present and the majority of individuals have evidence of dystonia.  Likewise, pyramidal signs are nearly always present.  Cerebellar dysarthria and titubation are often present with dystonic posturing and torticollis. 

Brain MRIs usually reveal cerebellar atrophy and widespread hypomyelination.  Two individuals in a single family had severe global psychomotor delays as well.  No sensory deficits were reported.  This disorder is progressive and patients in adulthood may require the use of a wheelchair.

Genetics

Homozygous mutations in the NKX6-2 (NKX6-2) gene (10q26.3) are responsible for this disorder.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported for the general condition.

References
Article Title: 

Mutations in NKX6-2 Cause Progressive Spastic Ataxia and Hypomyelination

Chelban V, Patel N, Vandrovcova J, Zanetti MN, Lynch DS, Ryten M, Botia JA, Bello O, Tribollet E, Efthymiou S, Davagnanam I; SYNAPSE Study Group, Bashiri FA, Wood NW, Rothman JE, Alkuraya FS, Houlden H. Mutations in NKX6-2 Cause Progressive Spastic Ataxia and Hypomyelination. Am J Hum Genet. 2017 Jun 1;100(6):969-977.

PubMed ID: 
28575651

Carey-Fineman-Ziter Syndrome

Clinical Characteristics
Ocular Features: 

Abnormal eye movements with prominent external ophthalmoplegia are hallmarks of this disease.  An oculomotor nerve palsy with limited abduction and some degree of facial palsy are usually present.  The Moebius sequence is present in many patients.  Epicanthal folds, downslanting lid fissures, and ptosis are frequently seen.

Systemic Features: 

Clinical signs are highly variable.  Unusual facies with features of the Pierre Robin complex are characteristic.  Micrognathia and retrognathia are often present with glossoptosis.  Hypotonia and failure to thrive are commonly seen.  Dysphagia and even absent swallowing likely contribute to this.  Respiratory insufficiency can be present from birth, often with laryngostenosis, and some patients develop pulmonary hypertension and restrictive lung disease as adults.  Progressive scoliosis may contribute to this.  Many patients have club feet with joint contractures.  Skull formation consisting of microcephaly, or macrocephaly, or plagiocephaly is commonly seen.  Cardiac septal defects are common.

Intellectual disability is present in some but not all individuals.  Neuronal heterotopias, enlarged ventricles, reduced white matter, a small brainstem, microcalcifications, and enlarged ventricles have been observed.

Genetics

Homozygous or compound heterozygosity of the MYMK gene (9q34) is responsible for this condition.  

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment for the general disorder has been reported.

References
Article Title: 

A defect in myoblast fusion underlies Carey-Fineman-Ziter syndrome

Di Gioia SA, Connors S, Matsunami N, Cannavino J, Rose MF, Gilette NM, Artoni P, de Macena Sobreira NL, Chan WM, Webb BD, Robson CD, Cheng L, Van Ryzin C, Ramirez-Martinez A, Mohassel P, Leppert M, Scholand MB, Grunseich C, Ferreira CR, Hartman T, Hayes IM, Morgan T, Markie DM, Fagiolini M, Swift A, Chines PS, Speck-Martins CE, Collins FS, Jabs EW, Bonnemann CG, Olson EN; Moebius Syndrome Research Consortium, Carey JC, Robertson SP, Manoli I, Engle EC. A defect in myoblast fusion underlies Carey-Fineman-Ziter syndrome. Nat Commun. 2017 Jul 6;8:16077. doi: 10.1038/ncomms16077.

PubMed ID: 
28681861

Möbius sequence, Robin complex, and hypotonia: severe expression of brainstem disruption spectrum versus Carey-Fineman-Ziter syndrome

Verloes A, Bitoun P, Heuskin A, Amrom D, van de Broeck H, Nikkel SM, Chudley AE, Prasad AN, Rusu C, Covic M, Toutain A, Moraine C, Parisi MA, Patton M, Martin JJ, Van Thienen MN. Mobius sequence, Robin complex, and hypotonia: severe expression of brainstem disruption spectrum versus Carey-Fineman-Ziter syndrome. Am J Med Genet A. 2004 Jun 15;127A(3):277-87.

PubMed ID: 
15150779

Gaze Palsy, Familial Horizontal, with Progressive Scoliosis 2

Clinical Characteristics
Ocular Features: 

Strabismus is present at birth.  Horizontal eye movements are restricted but vertical gaze can be normal.  The optic nerves appear normal.

Systemic Features: 

Hypotonia may be noted at birth but ankle clonus and spasticity can develop later.  Progressive kyphoscoliosis has been diagnosed as early as the age of 4 years and may result in restrictive lung disease requiring spine surgery by the second decade of life.  Developmental milestones such as walking and talking are delayed and intellectual development is subnormal.  Mirror movements may be present.  Gait may be unsteady but can be normal.

Brain MRI reveals a variety of malformations.  Agenesis of the corpus callosum is present and the white matter tracts appear disorganized.  The superior cerebellar peduncles fail to decussate and transverse pontine fibers may be absent.  The pons and midbrain are hypoplastic while there is a midline cleft throughout the brainstem resulting in a butterfly-shaped medulla.

Genetics

Homozygous mutations in the DCC gene (18q21) are responsible for this condition.  Three patients in 2 unrelated consanguineous families have been reported.  Studies suggest that the DCC gene product is important for forebrain and brainstem midline crossing of neurons.

See Gaze Palsy, Familial Horizontal, with Progressive Scoliosis 1 (607313) for another disorder with somewhat similar features.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Biallelic mutations in human DCC cause developmental split-brain syndrome

Jamuar SS, Schmitz-Abe K, D'Gama AM, Drottar M, Chan WM, Peeva M, Servattalab S, Lam AN, Delgado MR, Clegg NJ, Zayed ZA, Dogar MA, Alorainy IA, Jamea AA, Abu-Amero K, Griebel M, Ward W, Lein ES, Markianos K, Barkovich AJ, Robson CD, Grant PE, Bosley TM, Engle EC, Walsh CA, Yu TW. Biallelic mutations in human DCC cause developmental split-brain syndrome. Nat Genet. 2017 Apr;49(4):606-612.

PubMed ID: 
28250456

PEHO-Like Syndrome

Clinical Characteristics
Ocular Features: 

Poor visual fixation and attention has been noted during the first 6 months of life.  Optic atrophy has been described and epicanthal folds may be present.

Systemic Features: 

General hypotonia with developmental delay and progressive microcephaly are evident in the first 6-12 months of life.  Seizures may be present at birth or within the first month of life.  Edema of the feet, hands, and face are also present at birth.  Cognitive deficits and motor delays are usually evident during infancy.  The central hypotonia may be accompanied by peripheral spasticity.  Kyphoscoliosis often develops.  Other dysmorphic features include micrognathia, narrow forehead, short nose, and open mouth.

Brain imaging reveals coarse pachygyria, polymicrogyria, and dilated ventricles with hypoplastic corpus callosum and pons.  Cerebellar hypoplasia was found in one child. 

Genetics

This presumed autosomal recessive disorder is associated with homozygous mutations in the CCDC88A gene (2p16.1).  Three affected children have been reported in a consanguineous family.

A somewhat similar disorder known as PEHO syndrome (260565) results from homozygous mutations in the ZNHIT3 gene. 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

The PEHO syndrome

Riikonen R. The PEHO syndrome. Brain Dev. 2001 Nov;23(7):765-9. Review.

PubMed ID: 
11701291

Congenital Heart Defects, Dysmorphic Facies, and Intellectual Developmental Disorder

Clinical Characteristics
Ocular Features: 

The dysmorphic facial features primarily involve the periocular structures.  These include hypertelorism, ptosis, epicanthal folds, strabismus and upslanted palpebral fissures.

Systemic Features: 

Septal defects involving both the atrium and the ventricle are consistently present.  Pulmonary valve abnormalities are present in some patients.

Posteriorly rotated pinnae and a small mouth with a thin upper lip have been observed.  Camptodactyly and clinodactyly are common.  Some patients have mild microcephaly.

Global developmental delay is a consistent feature manifest as delays in walking and speech and eventual intellectual disability.  Feeding difficulties are common.  Hypotonia and hypermobile joints are often noted.  Imaging of the brain may reveal agenesis of the corpus callosum, incomplete formation of the inferior vermis, and leukomalacia of periventricular tissue.

Genetics

Heterozygous mutations have been identified in the CDK13 gene (7p14.1) in seven unrelated individuals.  Heterozygous parents may not have the full phenotype.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No treatment is available for the generalized condition.

References
Article Title: 

Distinct genetic architectures for syndromic and nonsyndromic congenital heart defects identified by exome sequencing

Sifrim A, Hitz MP, Wilsdon A, Breckpot J, Turki SH, Thienpont B, McRae J, Fitzgerald TW, Singh T, Swaminathan GJ, Prigmore E, Rajan D, Abdul-Khaliq H, Banka S, Bauer UM, Bentham J, Berger F, Bhattacharya S, Bu'Lock F, Canham N, Colgiu IG, Cosgrove C, Cox H, Daehnert I, Daly A, Danesh J, Fryer A, Gewillig M, Hobson E, Hoff K, Homfray T; INTERVAL Study., Kahlert AK, Ketley A, Kramer HH, Lachlan K, Lampe AK, Louw JJ, Manickara AK, Manase D, McCarthy KP, Metcalfe K, Moore C, Newbury-Ecob R, Omer SO, Ouwehand WH, Park SM, Parker MJ, Pickardt T, Pollard MO, Robert L, Roberts DJ, Sambrook J, Setchfield K, Stiller B, Thornborough C, Toka O, Watkins H, Williams D, Wright M, Mital S, Daubeney PE, Keavney B, Goodship J; UK10K Consortium., Abu-Sulaiman RM, Klaassen S, Wright CF, Firth HV, Barrett JC, Devriendt K, FitzPatrick DR, Brook JD; Deciphering Developmental Disorders Study., Hurles ME. Distinct genetic architectures for syndromic and nonsyndromic congenital heart defects identified by exome sequencing. Nat Genet. 2016 Sep;48(9):1060-5.

PubMed ID: 
27479907

Spastic Paraplegia, Intellectual Disability, Nystagmus, and Obesity

Clinical Characteristics
Ocular Features: 

Patients have deep-set eyes with nystagmus, reduced vision, and often an esotropia perhaps secondary to hypermetropia.  In one of 3 reported patients the optic discs were described pale.

Systemic Features: 

Prominent foreheads are present at birth along with full cheeks and a prominent forehead.  Children grow rapidly in the first year eventually reaching the 90th percentiles in weight, height, and head circumference although neurologically they are developmentally delayed.  Speech and walking may be delayed as well.  While limbs have increased tone together with hyperreflexia, the trunk exhibits hypotonia.

Brain imaging reveals delayed myelination, dilated lateral ventricles, reduced while matter, and cerebral atrophy.

Genetics

Heterozygous mutations in the KIDINS220 gene (2p25.1) have been identified in 3 unrelated patients.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Heterozygous KIDINS220/ARMS nonsense variants cause spastic paraplegia, intellectual disability, nystagmus, and obesity

Josifova DJ, Monroe GR, Tessadori F, de Graaff E, van der Zwaag B, Mehta SG; DDD Study., Harakalova M, Duran KJ, Savelberg SM, Nijman IJ, Jungbluth H, Hoogenraad CC, Bakkers J, Knoers NV, Firth HV, Beales PL, van Haaften G, van Haelst MM. Heterozygous KIDINS220/ARMS nonsense variants cause spastic paraplegia, intellectual disability, nystagmus, and obesity. Hum Mol Genet. 2016 Jun 1;25(11):2158-2167.

PubMed ID: 
27005418

Encephalopathy, Progressive, with Amyotrophy and Optic Atrophy

Clinical Characteristics
Ocular Features: 

Optic atrophy is present.

Systemic Features: 

This is a progressive neurodegenerative condition in which hypotonia and delayed development are evident between birth and 14 months of age.  Developmental milestones, if attained, soon regress accompanied by distal amyotrophy, cognitive impairment that may be severe, ataxia, spastic tetraplegia, dysarthria, and scoliosis.  Seizures often occur.

Brain imaging reveals cerebellar and cerebral atrophy.  Iron accumulation may be seen in the pallidum and substantia nigra.  The corpus callosum appears abnormally thin.  Muscle biopsy shows evidence of denervation atrophy.

Genetics

Homozygous or compound heterozygous mutations in the TBCE gene (1q42.3) can cause this disorder.  

Biallelic mutations in the same gene also cause Kenny-Caffey syndrome type 1 (244460) and a hypoparathyroidism dysmorphism syndrome (241410).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

TBCE Mutations Cause Early-Onset Progressive Encephalopathy with Distal Spinal Muscular Atrophy

Sferra A, Baillat G, Rizza T, Barresi S, Flex E, Tasca G, D'Amico A, Bellacchio E, Ciolfi A, Caputo V, Cecchetti S, Torella A, Zanni G, Diodato D, Piermarini E, Niceta M, Coppola A, Tedeschi E, Martinelli D, Dionisi-Vici C, Nigro V, Dallapiccola B, Compagnucci C, Tartaglia M, Haase G, Bertini E. TBCE Mutations Cause Early-Onset Progressive Encephalopathy with Distal Spinal Muscular Atrophy. Am J Hum Genet. 2016 Oct 6;99(4):974-983.

PubMed ID: 
27666369

Biallelic Mutations in TBCD, Encoding the Tubulin Folding Cofactor D, Perturb Microtubule Dynamics and Cause Early-Onset Encephalopathy

Flex E, Niceta M, Cecchetti S, Thiffault I, Au MG, Capuano A, Piermarini E, Ivanova AA, Francis JW, Chillemi G, Chandramouli B, Carpentieri G, Haaxma CA, Ciolfi A, Pizzi S, Douglas GV, Levine K, Sferra A, Dentici ML, Pfundt RR, Le Pichon JB, Farrow E, Baas F, Piemonte F, Dallapiccola B, Graham JM Jr, Saunders CJ, Bertini E, Kahn RA, Koolen DA, Tartaglia M. Biallelic Mutations in TBCD, Encoding the Tubulin Folding Cofactor D, Perturb Microtubule Dynamics and Cause Early-Onset Encephalopathy. Am J Hum Genet. 2016 Oct 6;99(4):962-973.

PubMed ID: 
27666370

Epileptic Encephalopathy, Early Infantile 48

Clinical Characteristics
Ocular Features: 

Poor eye contact is present from infancy.  Optic atrophy has been reported in several patients and features of retinitis pigmentosa were present in sibs of one family.

Systemic Features: 

Infants usually present with hypotonia and feeding difficulties.  Global developmental delay is also noted early and becomes more obvious with time.  Seizures are often seen early and become intractable.  Many individuals have microcephaly.  Hypermobility with dyskinesias and hyporeflexia are often present.  Speech is generally absent and many individuals are unable to sit or walk.

Brain imaging often shows atrophy of the cerebrum and cerebellum accompanied by enlarged ventricles and a thin corpus callosum.

Genetics

Homozygous or compound heterozygous mutations in the AP3B2 gene (15q25.2) can be responsible for this condition.

For another somewhat similar condition see early onset epileptic encephalopathy 28 (616211) with autosomal recessive inheritance.  For an autosomal dominant condition with a similar clinical picture, see early onset epileptic encephalopathy 47 (617166).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Autosomal-Recessive Mutations in AP3B2, Adaptor-Related Protein Complex 3 Beta 2 Subunit, Cause an Early-Onset Epileptic Encephalopathy with Optic Atrophy

Assoum M, Philippe C, Isidor B, Perrin L, Makrythanasis P, Sondheimer N, Paris C, Douglas J, Lesca G, Antonarakis S, Hamamy H, Jouan T, Duffourd Y, Auvin S, Saunier A, Begtrup A, Nowak C, Chatron N, Ville D, Mireskandari K, Milani P, Jonveaux P, Lemeur G, Milh M, Amamoto M, Kato M, Nakashima M, Miyake N, Matsumoto N, Masri A, Thauvin-Robinet C, Riviere JB, Faivre L, Thevenon J. Autosomal-Recessive Mutations in AP3B2, Adaptor-Related Protein Complex 3 Beta 2 Subunit, Cause an Early-Onset Epileptic Encephalopathy with Optic Atrophy. Am J Hum Genet. 2016 Dec 1;99(6):1368-1376.

PubMed ID: 
27889060

Clinical genomics expands the morbid genome of intellectual disability and offers a high diagnostic yield

Anazi S, Maddirevula S, Faqeih E, Alsedairy H, Alzahrani F, Shamseldin HE, Patel N, Hashem M, Ibrahim N, Abdulwahab F, Ewida N, Alsaif HS, Al Sharif H, Alamoudi W, Kentab A, Bashiri FA, Alnaser M, AlWadei AH, Alfadhel M, Eyaid W, Hashem A, Al Asmari A, Saleh MM, AlSaman A, Alhasan KA, Alsughayir M, Al Shammari M, Mahmoud A, Al-Hassnan ZN, Al-Husain M, Osama Khalil R, Abd El Meguid N, Masri A, Ali R, Ben-Omran T, El Fishway P, Hashish A, Ercan Sencicek A, State M, Alazami AM, Salih MA, Altassan N, Arold ST, Abouelhoda M, Wakil SM, Monies D, Shaheen R, Alkuraya FS. Clinical genomics expands the morbid genome of intellectual disability and offers a high diagnostic yield. Mol Psychiatry. 2016 Jul 19. doi: 10.1038/mp.2016.113. [Epub ahead of print].

PubMed ID: 
27431290

Encephalopathy, Early-Onset, With Brain Atrophy and Thin Corpus Callosum

Clinical Characteristics
Ocular Features: 

Optic atrophy is present in many patients and may be present early since lack of visual tracking or eye contact may be noted at birth.  Sparse eyebrows, upslanting palpebral fissures, and hypertelorism have also been reported.

Systemic Features: 

Severe hypotonia is present at birth often causing respiratory distress in the neonate.  Spasticity can develop later.  Growth failure with progressive microcephaly is present in infants.  Brain imaging often reveals diffuse atrophy of structures including the cerebellum, brainstem, spinal cord, and cerebrum.  Tongue fasciculations have been observed.   Micrognathia and widely spaced teeth are sometimes present.  Several patients have died during infancy.

Genetics

Homozygous mutations in the TBCD (17q25.3) are responsible for this disorder.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Biallelic Mutations in TBCD, Encoding the Tubulin Folding Cofactor D, Perturb Microtubule Dynamics and Cause Early-Onset Encephalopathy

Flex E, Niceta M, Cecchetti S, Thiffault I, Au MG, Capuano A, Piermarini E, Ivanova AA, Francis JW, Chillemi G, Chandramouli B, Carpentieri G, Haaxma CA, Ciolfi A, Pizzi S, Douglas GV, Levine K, Sferra A, Dentici ML, Pfundt RR, Le Pichon JB, Farrow E, Baas F, Piemonte F, Dallapiccola B, Graham JM Jr, Saunders CJ, Bertini E, Kahn RA, Koolen DA, Tartaglia M. Biallelic Mutations in TBCD, Encoding the Tubulin Folding Cofactor D, Perturb Microtubule Dynamics and Cause Early-Onset Encephalopathy. Am J Hum Genet. 2016 Oct 6;99(4):962-973.

PubMed ID: 
27666370

Biallelic TBCD Mutations Cause Early-Onset Neurodegenerative Encephalopathy

Miyake N, Fukai R, Ohba C, Chihara T, Miura M, Shimizu H, Kakita A, Imagawa E, Shiina M, Ogata K, Okuno-Yuguchi J, Fueki N, Ogiso Y, Suzumura H, Watabe Y, Imataka G, Leong HY, Fattal-Valevski A, Kramer U, Miyatake S, Kato M, Okamoto N, Sato Y, Mitsuhashi S, Nishino I, Kaneko N, Nishiyama A, Tamura T, Mizuguchi T, Nakashima M, Tanaka F, Saitsu H, Matsumoto N. Biallelic TBCD Mutations Cause Early-Onset Neurodegenerative Encephalopathy. Am J Hum Genet. 2016 Oct 6;99(4):950-961.

PubMed ID: 
27666374

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