Table 1 Summary of patients harboring 21q deletions overlapping with patients 1–5 and corresponding clinical features

Patients 1-2-3 (present study)

53 (#1), 20 (#2), 18 (#3)

Obsessive-compulsive disorders, impaired social interactions, aggressiveness, delayed speech and language development, mild facial dismorphisms

chr21:21754822-32380347

10.63

112 (52)

Paternal

Pathogenic

Patient 4 (present study)

6

Intellectual disability, global movement impairment, dysmorphic features, dyslexia, dyscalculia, primary amenorrhoea, obesity, pituitary microadenoma

chr21:13048294-27532614

14.48

117 (21)

De novo

Pathogenic

Patient 5 (present study)

4

Intellectual disability, mild psychomotor delay, speech delay, hypotonia, DCD ^(a), Duane syndrome type 3, bilateral iris/choroidal coloboma

chr21:14000146-27785985

13.79

112 (23)

De novo

Pathogenic

chr16:28813473-29030738

0.22

35 (24)

Maternal

Pathogenic

Case 1 (Petit et al., 2015) [24] Decipher#276325

7

Behavioural/psychiatric abnormality, attention deficit, impaired social interactions, frustration, aggressiveness, delayed speech and language development

chr21:21062316-24943120

3.88

16 (1)

Maternal

Unknown

Case 2 (Petit et al., 2015) [24] Decipher#254181

9

Global developmental delay, speech delay, hyperactivity, impairment of social interactions

chr21:15619936-23525918

7.91

50 (9)

Paternal (mosaicism)

Unknown

Case 3 (Petit et al., 2015) [24] Decipher#274603

5

Global developmental delay, hypotonia, constipation, impaired social interactions

chr21:16079383-24575840

8.50

48 (7)

Unknown

Unknown

KKI patient 3 - cohort A (Roberson et al., 2011)

6

Speech delay, mild/moderate mental retardation, dysmorfic features, hypotonia, GERD ^(b), eczema, dermatographism

chr21:16814345-33232252

16.42

159 (69)

De novo

Unknown

chr4:65863868-66006319

0.14

0

Maternal

Unlikely pathogenic

chr14:22625231–22795061 ^(c)

0.17 ^(c)

2 (2)

Paternal

Unlikely pathogenic

GM00137 - cohort B (Roberson et al., 2011) [1]

6

Severe psychomotor retardation, microcephaly, dysmorphic features, bilateral iris coloboma

chr21:13403408-28392024

14.99

124 (23)

Unknown

Unknown

chr4:68917-11238519

11.17

229 (122)

Unknown

Unknown

GM06918 - cohort B (Roberson et al., 2011) [1]

9

Mental retardation, dysmorphic features

chr21:14981488-32298829

17.32

156 (61)

De novo

Unknown

Haldeman-Englert et al., 2010 [13]

2

Poor social interactions, speech delay, mild dysmorphic features, PDD-NOS ^(d)

chr21:21085454-29813876

8.73

62 (18)

De novo

Pathogenic

Case 31 (Lyle et al., 2009) [2]

Unknown

Dysmorphic features, short stature, mental retardation, synbrachydactily

chr21:12965809-30890916

17.93

180 (56)

Unknown

Unknown

Case 32 (Lyle et al., 2009) [2]

Unknown

Dysmorphic features, short stature, mental retardation, microcephaly, clinodactily, hypotonia

chr21:12965809-30218169

17.26

145 (31)

Unknown

Unknown

Case 33 (Lyle et al., 2009) [2]

Unknown

Mental retardation

chr21:12965809-26199556

13.23

108 (15)

Unknown

Unknown

Hannachi et al., 2011 [20]

26

Moderate mental retardation, minor brain malformations, craniofacial dysmorphic features, azoospermia, diffuse cerebral atrophy

chr21:13603505-29194209

15.59

130 (23)

Maternal

Likely pathogenic

Decipher#285024

2

Ataxia, intellectual disability, poor speech, lower limb spasticity, speech articulation difficulties

chr21:13224687-27912651

14.69

124 (23)

Unknown

Pathogenic

Decipher#285691

10

Cognitive impairment, generalized myoclonic seizures, microcephaly, asymmetry of the ears

chr21:13045202-33522318

20.48

217 (76)

Unknown

Pathogenic

ECARUCA#4777

16

Mental retardation, seizures/abnormal EEG ^(e), short stature, prominent maxilla, dislocation of hip, atrial septum defect

chr21:14166659-20412272

6.25

66 (13)

De novo

Unknown

chr21:43013575-46699983

3.69

116 (67)

De novo

Unknown

ECARUCA#4841

9

Mental retardation, seizures/abnormal EEG ^(e), facial dysmorphisms

chr21:15292766-19704615

4.41

31 (6)

De novo

Unknown