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Multiple congenital anomalies-hypotonia-seizures syndrome 2(MCAHS2)

MedGen UID:
477139
Concept ID:
C3275508
Disease or Syndrome
Synonyms: EPILEPTIC ENCEPHALOPATHY, EARLY INFANTILE, 20; GLYCOSYLPHOSPHATIDYLINOSITOL BIOSYNTHESIS DEFECT 4; MCAHS2
Modes of inheritance:
X-linked recessive inheritance
MedGen UID:
375779
Concept ID:
C1845977
Finding
Source: Orphanet
A mode of inheritance that is observed for recessive traits related to a gene encoded on the X chromosome. In the context of medical genetics, X-linked recessive disorders manifest in males (who have one copy of the X chromosome and are thus hemizygotes), but generally not in female heterozygotes who have one mutant and one normal allele.
 
Gene (location): PIGA (Xp22.2)
 
Monarch Initiative: MONDO:0010466
OMIM®: 300868
Orphanet: ORPHA300496

Definition

Multiple congenital anomalies-hypotonia-seizures syndrome-2 (MCAHS2) is an X-linked recessive neurodevelopmental disorder characterized by dysmorphic features, neonatal hypotonia, early-onset myoclonic seizures, and variable congenital anomalies involving the central nervous, cardiac, and urinary systems. Some affected individuals die in infancy (summary by Johnston et al., 2012). The phenotype shows clinical variability with regard to severity and extraneurologic features. However, most patients present in infancy with early-onset epileptic encephalopathy associated with developmental arrest and subsequent severe neurologic disability; these features are consistent with a form of developmental and epileptic encephalopathy (DEE) (summary by Belet et al., 2014, Kato et al., 2014). The disorder is caused by a defect in glycosylphosphatidylinositol (GPI) biosynthesis. For a discussion of genetic heterogeneity of MCAHS, see MCAHS1 (614080). For a discussion of nomenclature and genetic heterogeneity of DEE, see 308350. For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293). [from OMIM]

Clinical features

From HPO
Vesicoureteral reflux
MedGen UID:
21852
Concept ID:
C0042580
Disease or Syndrome
Vesicoureteral reflux (VUR) is characterized by the reflux of urine from the bladder into the ureters and sometimes into the kidneys. It is a risk factor for urinary tract infections. Primary VUR results from a developmental defect of the ureterovesical junction (UVJ). In combination with intrarenal reflux, the resulting inflammatory reaction may result in renal injury or scarring, also called reflux nephropathy (RN). Extensive renal scarring impairs renal function and may predispose patients to hypertension, proteinuria, and renal insufficiency (summary by Lu et al., 2007). Genetic Heterogeneity of Vesicoureteral Reflux A locus designated VUR1 maps to chromosome 1p13. VUR2 (610878) is caused by mutation in the ROBO2 gene (602431) on chromosome 3p12; VUR3 (613674) is caused by mutation in the SOX17 gene (610928) on chromosome 8q11; VUR4 (614317) maps to chromosome 5; VUR5 (614318) maps to chromosome 13; VUR6 (614319) maps to chromosome 18; VUR7 (615390) maps to chromosome 12; and VUR8 (615963) is caused by mutation in the TNXB gene (600985) on chromosome 6p21. A possible X-linked form has been reported (VURX; 314550).
Duplicated collecting system
MedGen UID:
346936
Concept ID:
C1858565
Anatomical Abnormality
A duplication of the collecting system of the kidney, defined as a kidney with two (instead of, normally, one) pyelocaliceal systems. The pyelocaliceal system is comprised of the renal pelvis and calices. The duplicated renal collecting system can be associated with a single ureter or with double ureters. In the latter case, the two ureters empty separately into the bladder or fuse to form a single ureteral orifice.
Micropenis
MedGen UID:
1633603
Concept ID:
C4551492
Congenital Abnormality
Abnormally small penis. At birth, the normal penis is about 3 cm (stretched length from pubic tubercle to tip of penis) with micropenis less than 2.0-2.5 cm.
Broad palm
MedGen UID:
75535
Concept ID:
C0264142
Congenital Abnormality
For children from birth to 4 years of age the palm width is more than 2 SD above the mean; for children from 4 to 16 years of age the palm width is above the 95th centile; or, the width of the palm appears disproportionately wide for the length.
Knee flexion contracture
MedGen UID:
98042
Concept ID:
C0409355
Finding
A bent (flexed) knee joint that cannot be straightened actively or passively.
Patent ductus arteriosus
MedGen UID:
4415
Concept ID:
C0013274
Congenital Abnormality
In utero, the ductus arteriosus (DA) serves to divert ventricular output away from the lungs and toward the placenta by connecting the main pulmonary artery to the descending aorta. A patent ductus arteriosus (PDA) in the first 3 days of life is a physiologic shunt in healthy term and preterm newborn infants, and normally is substantially closed within about 24 hours after bith and completely closed after about three weeks. Failure of physiologcal closure is referred to a persistent or patent ductus arteriosus (PDA). Depending on the degree of left-to-right shunting, PDA can have clinical consequences.
Atrial septal defect
MedGen UID:
6753
Concept ID:
C0018817
Congenital Abnormality
Atrial septal defect (ASD) is a congenital abnormality of the interatrial septum that enables blood flow between the left and right atria via the interatrial septum.
Birth length greater than 97th percentile
MedGen UID:
326443
Concept ID:
C1839271
Finding
Large for gestational age
MedGen UID:
341215
Concept ID:
C1848395
Finding
The term large for gestational age applies to babies whose birth weight lies above the 90th percentile for that gestational age.
Overgrowth
MedGen UID:
376550
Concept ID:
C1849265
Finding
Excessive postnatal growth which may comprise increased weight, increased length, and/or increased head circumference.
Hepatomegaly
MedGen UID:
42428
Concept ID:
C0019209
Finding
Abnormally increased size of the liver.
Cirrhosis of liver
MedGen UID:
7368
Concept ID:
C0023890
Disease or Syndrome
A chronic disorder of the liver in which liver tissue becomes scarred and is partially replaced by regenerative nodules and fibrotic tissue resulting in loss of liver function.
Microvesicular hepatic steatosis
MedGen UID:
376784
Concept ID:
C1850415
Finding
A form of hepatic steatosis characterized by the presence of small, lipid-laden vesicles in the affected hepatocytes.
Elevated hepatic iron concentration
MedGen UID:
868497
Concept ID:
C4022891
Finding
An increased level of iron in liver tissues.
Hearing impairment
MedGen UID:
235586
Concept ID:
C1384666
Disease or Syndrome
A decreased magnitude of the sensory perception of sound.
Overfolded helix
MedGen UID:
325239
Concept ID:
C1837731
Finding
A condition in which the helix is folded over to a greater degree than normal. That is, excessive curling of the helix edge, whereby the free edge is parallel to the plane of the ear.
Gliosis
MedGen UID:
4899
Concept ID:
C0017639
Pathologic Function
Gliosis is the focal proliferation of glial cells in the central nervous system.
Spasticity
MedGen UID:
7753
Concept ID:
C0026838
Sign or Symptom
A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes.
Hyperreflexia
MedGen UID:
57738
Concept ID:
C0151889
Finding
Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles.
Cerebellar hypoplasia
MedGen UID:
120578
Concept ID:
C0266470
Congenital Abnormality
Cerebellar hypoplasia is a descriptive term implying a cerebellum with a reduced volume, but a normal shape and is stable over time.
Hypoplasia of the corpus callosum
MedGen UID:
138005
Concept ID:
C0344482
Congenital Abnormality
Underdevelopment of the corpus callosum.
Absent septum pellucidum
MedGen UID:
96561
Concept ID:
C0431371
Congenital Abnormality
Absence of the septum pellucidum (meaning translucent wall in Latin - SP), also known as the ventricle of Sylvius. The septum pellucidum is a thin, triangular double membrane separating the frontal horns of the right and left lateral ventricles of the brain. It extends between the anterior portion of the corpus callosum, and the body of the fornix and its width varies from 1.5 to 3.0 mm.
Epileptic encephalopathy
MedGen UID:
452596
Concept ID:
C0543888
Disease or Syndrome
A condition in which epileptiform abnormalities are believed to contribute to the progressive disturbance in cerebral function. Epileptic encephalaopathy is characterized by (1) electrographic EEG paroxysmal activity that is often aggressive, (2) seizures that are usually multiform and intractable, (3) cognitive, behavioral and neurological deficits that may be relentless, and (4) sometimes early death.
Global developmental delay
MedGen UID:
107838
Concept ID:
C0557874
Finding
A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.
Hypsarrhythmia
MedGen UID:
195766
Concept ID:
C0684276
Finding
Hypsarrhythmia is abnormal interictal high amplitude waves and a background of irregular spikes. There is continuous (during wakefulness), high-amplitude (>200 Hz), generalized polymorphic slowing with no organized background and multifocal spikes demonstrated by electroencephalography (EEG).
Abnormal cerebral white matter morphology
MedGen UID:
181756
Concept ID:
C0948163
Pathologic Function
An abnormality of the cerebral white matter.
Lower limb spasticity
MedGen UID:
220865
Concept ID:
C1271100
Finding
Spasticity (velocity-dependent increase in tonic stretch reflexes with increased muscle tone and hyperexcitable tendon reflexes) in the muscles of the lower limbs, hips, and pelvis
Upper limb spasticity
MedGen UID:
220882
Concept ID:
C1273957
Finding
Delayed myelination
MedGen UID:
224820
Concept ID:
C1277241
Finding
Delayed myelination.
Neuronal loss in central nervous system
MedGen UID:
342515
Concept ID:
C1850496
Finding
Absent speech
MedGen UID:
340737
Concept ID:
C1854882
Finding
Complete lack of development of speech and language abilities.
Olfactory lobe agenesis
MedGen UID:
344477
Concept ID:
C1855331
Finding
Lateral ventricle dilatation
MedGen UID:
383904
Concept ID:
C1856409
Pathologic Function
Brisk reflexes
MedGen UID:
382164
Concept ID:
C2673700
Finding
Tendon reflexes that are noticeably more active than usual (conventionally denoted 3+ on clinical examination). Brisk reflexes may or may not indicate a neurological lesion. They are distinguished from hyperreflexia by the fact that hyerreflexia is characterized by hyperactive repeating (clonic) reflexes, which are considered to be always abnormal.
Generalized myoclonic seizure
MedGen UID:
892704
Concept ID:
C4021759
Disease or Syndrome
A generalized myoclonic seizure is a type of generalized motor seizure characterised by bilateral, sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus.
Abnormal pons morphology
MedGen UID:
870459
Concept ID:
C4024905
Anatomical Abnormality
A structural abnormality of the pons.
Cerebral cortical atrophy
MedGen UID:
1646740
Concept ID:
C4551583
Disease or Syndrome
Atrophy of the cortex of the cerebrum.
Micrognathia
MedGen UID:
44428
Concept ID:
C0025990
Congenital Abnormality
Developmental hypoplasia of the mandible.
Hypotonia
MedGen UID:
10133
Concept ID:
C0026827
Finding
Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.
Flexion contracture
MedGen UID:
83069
Concept ID:
C0333068
Anatomical Abnormality
A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints.
Elbow flexion contracture
MedGen UID:
98367
Concept ID:
C0409338
Acquired Abnormality
An elbow contracture that limits the ability of the elbow joint to be extended (straightened), meaning that the elbow is fixed in an flexed (bent) position.
Hip contracture
MedGen UID:
140815
Concept ID:
C0409354
Acquired Abnormality
Secondary microcephaly
MedGen UID:
608952
Concept ID:
C0431352
Finding
Head circumference which falls below 2 standard deviations below the mean for age and gender because of insufficient head growth after birth.
Large fontanelles
MedGen UID:
105329
Concept ID:
C0456132
Finding
In newborns, the two frontal bones, two parietal bones, and one occipital bone are joined by fibrous sutures, which form a small posterior fontanelle, and a larger, diamond-shaped anterior fontanelle. These regions allow for the skull to pass the birth canal and for later growth. The fontanelles gradually ossify, whereby the posterior fontanelle usually closes by eight weeks and the anterior fontanelle by the 9th to 16th month of age. Large fontanelles are diagnosed if the fontanelles are larger than age-dependent norms.
Thoracic hypoplasia
MedGen UID:
373339
Concept ID:
C1837482
Congenital Abnormality
Prominent occiput
MedGen UID:
381255
Concept ID:
C1853737
Finding
Increased convexity of the occiput (posterior part of the skull).
Axial hypotonia
MedGen UID:
342959
Concept ID:
C1853743
Finding
Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk.
Malar flattening
MedGen UID:
347616
Concept ID:
C1858085
Finding
Underdevelopment of the malar prominence of the jugal bone (zygomatic bone in mammals), appreciated in profile, frontal view, and/or by palpation.
Metopic synostosis
MedGen UID:
395990
Concept ID:
C1860819
Congenital Abnormality
Premature fusion of the metopic suture.
Macrocephaly
MedGen UID:
745757
Concept ID:
C2243051
Finding
Occipitofrontal (head) circumference greater than 97th centile compared to appropriate, age matched, sex-matched normal standards. Alternatively, a apparently increased size of the cranium.
Increased head circumference
MedGen UID:
909477
Concept ID:
C4083076
Finding
An abnormally increased head circumference in a growing child. Head circumference is measured with a nonelastic tape and comprises the distance from above the eyebrows and ears and around the back of the head. The measured HC is then plotted on an appropriate growth chart.
Microcephaly
MedGen UID:
1644158
Concept ID:
C4551563
Finding
Head circumference below 2 standard deviations below the mean for age and gender.
Respiratory failure
MedGen UID:
257837
Concept ID:
C1145670
Disease or Syndrome
A severe form of respiratory insufficiency characterized by inadequate gas exchange such that the levels of oxygen or carbon dioxide cannot be maintained within normal limits.
Seborrheic dermatitis
MedGen UID:
19912
Concept ID:
C0036508
Disease or Syndrome
Seborrheic dermatitis is a form of eczema which is closely related to dandruff. It causes dry or greasy peeling of the scalp, eyebrows, and face, and sometimes trunk.
Elevated circulating alkaline phosphatase concentration
MedGen UID:
727252
Concept ID:
C1314665
Finding
Abnormally increased serum levels of alkaline phosphatase activity.
Narrow mouth
MedGen UID:
44435
Concept ID:
C0026034
Congenital Abnormality
Distance between the commissures of the mouth more than 2 SD below the mean. Alternatively, an apparently decreased width of the oral aperture (subjective).
Isolated Pierre-Robin syndrome
MedGen UID:
19310
Concept ID:
C0031900
Congenital Abnormality
Pierre Robin sequence is a craniofacial anomaly comprising mandibular hypoplasia, cleft secondary palate, and glossoptosis leading to life-threatening obstructive apnea and feeding difficulaties during the neonatal period (summary by Tan et al., 2013).
Microdontia
MedGen UID:
66008
Concept ID:
C0240340
Congenital Abnormality
Decreased size of the teeth, which can be defined as a mesiodistal tooth diameter (width) more than 2 SD below mean. Alternatively, an apparently decreased maximum width of tooth.
High palate
MedGen UID:
66814
Concept ID:
C0240635
Congenital Abnormality
Height of the palate more than 2 SD above the mean (objective) or palatal height at the level of the first permanent molar more than twice the height of the teeth (subjective).
Gingival overgrowth
MedGen UID:
87712
Concept ID:
C0376480
Finding
Hyperplasia of the gingiva (that is, a thickening of the soft tissue overlying the alveolar ridge. The degree of thickening ranges from involvement of the interdental papillae alone to gingival overgrowth covering the entire tooth crown.
Upslanted palpebral fissure
MedGen UID:
98390
Concept ID:
C0423109
Finding
The palpebral fissure inclination is more than two standard deviations above the mean for age (objective); or, the inclination of the palpebral fissure is greater than typical for age.
Short neck
MedGen UID:
99267
Concept ID:
C0521525
Finding
Diminished length of the neck.
Depressed nasal bridge
MedGen UID:
373112
Concept ID:
C1836542
Finding
Posterior positioning of the nasal root in relation to the overall facial profile for age.
Anteverted nares
MedGen UID:
326648
Concept ID:
C1840077
Finding
Anteriorly-facing nostrils viewed with the head in the Frankfurt horizontal and the eyes of the observer level with the eyes of the subject. This gives the appearance of an upturned nose (upturned nasal tip).
Widely spaced teeth
MedGen UID:
337093
Concept ID:
C1844813
Finding
Increased spaces (diastemata) between most of the teeth in the same dental arch.
Coarse facial features
MedGen UID:
335284
Concept ID:
C1845847
Finding
Absence of fine and sharp appearance of brows, nose, lips, mouth, and chin, usually because of rounded and heavy features or thickened skin with or without thickening of subcutaneous and bony tissues.
Triangular mouth
MedGen UID:
336578
Concept ID:
C1849341
Finding
The presence of a triangular form of the mouth.
Downturned corners of mouth
MedGen UID:
356471
Concept ID:
C1866195
Anatomical Abnormality
A morphological abnormality of the mouth in which the angle of the mouth is downturned. The oral commissures are positioned inferior to the midline labial fissure.
Ichthyosis
MedGen UID:
7002
Concept ID:
C0020757
Disease or Syndrome
An abnormality of the skin characterized the presence of excessive amounts of dry surface scales on the skin resulting from an abnormality of keratinization.
Small nail
MedGen UID:
537942
Concept ID:
C0263523
Finding
A nail that is diminished in length and width, i.e., underdeveloped nail.
Abnormality of skin pigmentation
MedGen UID:
224697
Concept ID:
C1260926
Finding
An abnormality of the pigmentation of the skin.
Breech presentation
MedGen UID:
654
Concept ID:
C0006157
Pathologic Function
A position of the fetus at delivery in which the fetus enters the birth canal with the buttocks or feet first.
Fetal distress
MedGen UID:
5164
Concept ID:
C0015930
Pathologic Function
An intrauterine state characterized by suboptimal values in the fetal heart rate, oxygenation of fetal blood, or other parameters indicative of compromise of the fetus. Signs of fetal distress include repetitive variable decelerations, fetal tachycardia or bradycardia, late decelerations, or low biophysical profile.
Polyhydramnios
MedGen UID:
6936
Concept ID:
C0020224
Pathologic Function
The presence of excess amniotic fluid in the uterus during pregnancy.
Hydrops fetalis
MedGen UID:
6947
Concept ID:
C0020305
Disease or Syndrome
The abnormal accumulation of fluid in two or more fetal compartments, including ascites, pleural effusion, pericardial effusion, and skin edema.
Bilateral fetal pyelectasis
MedGen UID:
869105
Concept ID:
C4023523
Disease or Syndrome
A bilateral form of fetal pyelectasis.
Hypertelorism
MedGen UID:
9373
Concept ID:
C0020534
Finding
Although hypertelorism means an excessive distance between any paired organs (e.g., the nipples), the use of the word has come to be confined to ocular hypertelorism. Hypertelorism occurs as an isolated feature and is also a feature of many syndromes, e.g., Opitz G syndrome (see 300000), Greig cephalopolysyndactyly (175700), and Noonan syndrome (163950) (summary by Cohen et al., 1995).
Cerebral visual impairment
MedGen UID:
890568
Concept ID:
C4048268
Pathologic Function
A form of loss of vision caused by damage to the visual cortex rather than a defect in the eye.

Term Hierarchy

Follow this link to review classifications for Multiple congenital anomalies-hypotonia-seizures syndrome 2 in Orphanet.

Professional guidelines

PubMed

Loong L, Tardivo A, Knaus A, Hashim M, Pagnamenta AT, Alt K, Böhrer-Rabel H, Caro-Llopis A, Cole T, Distelmaier F, Edery P, Ferreira CR, Jezela-Stanek A, Kerr B, Kluger G, Krawitz PM, Kuhn M, Lemke JR, Lesca G, Lynch SA, Martinez F, Maxton C, Mierzewska H, Monfort S, Nicolai J, Orellana C, Pal DK, Płoski R, Quarrell OW, Rosello M, Rydzanicz M, Sabir A, Śmigiel R, Stegmann APA, Stewart H, Stumpel C, Szczepanik E, Tzschach A, Wolfe L, Taylor JC, Murakami Y, Kinoshita T, Bayat A, Kini U
Genet Med 2023 Jan;25(1):37-48. Epub 2022 Nov 2 doi: 10.1016/j.gim.2022.09.007. PMID: 36322149
Fleming L, Lemmon M, Beck N, Johnson M, Mu W, Murdock D, Bodurtha J, Hoover-Fong J, Cohn R, Bosemani T, Barañano K, Hamosh A
Am J Med Genet A 2016 Jan;170A(1):77-86. Epub 2015 Sep 23 doi: 10.1002/ajmg.a.37369. PMID: 26394714Free PMC Article

Recent clinical studies

Diagnosis

Yang J, Wang Q, Zhuo Q, Tian H, Li W, Luo F, Zhang J, Bi D, Peng J, Zhou D, Xin H
Mol Genet Genomic Med 2018 Sep;6(5):739-748. Epub 2018 Jul 4 doi: 10.1002/mgg3.428. PMID: 29974678Free PMC Article
Brodsky RA
Blood 2014 Oct 30;124(18):2804-11. Epub 2014 Sep 18 doi: 10.1182/blood-2014-02-522128. PMID: 25237200Free PMC Article
Belet S, Fieremans N, Yuan X, Van Esch H, Verbeeck J, Ye Z, Cheng L, Brodsky BR, Hu H, Kalscheuer VM, Brodsky RA, Froyen G
Hum Mutat 2014 Mar;35(3):350-5. Epub 2014 Jan 13 doi: 10.1002/humu.22498. PMID: 24357517

Prognosis

Yang J, Wang Q, Zhuo Q, Tian H, Li W, Luo F, Zhang J, Bi D, Peng J, Zhou D, Xin H
Mol Genet Genomic Med 2018 Sep;6(5):739-748. Epub 2018 Jul 4 doi: 10.1002/mgg3.428. PMID: 29974678Free PMC Article

Clinical prediction guides

Yang J, Wang Q, Zhuo Q, Tian H, Li W, Luo F, Zhang J, Bi D, Peng J, Zhou D, Xin H
Mol Genet Genomic Med 2018 Sep;6(5):739-748. Epub 2018 Jul 4 doi: 10.1002/mgg3.428. PMID: 29974678Free PMC Article

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