Table 1

Clinical findings in individuals harbouring biallelic MAB21L1 variants

	Family 1				Family 2	Family 3	Family 4*	Family 5*			Family 6†
	Patient 1	Patient 2	Patient 3	Patient 4	Patent 5	Patient 6	Patient 7	Patient 8	Patient 9	Patient 10	Patient 11
MAB21L1 mutation	c.841delG, p.Glut281fs*20				c.698 A>C, p.Gln233Pro	c.279_286delACTGCCCG (p.Ser93Serfs*48)	c.859delC, p.Arg287Glufs*14	c.840C>G; p.Tyr280*			c.735dupG, p.Cys246Leufs*18
Ancestry	Persian				Persian	Lebanese Shia	Turkish	Turkish			Algerian
Sex	Female	Female	Male	Male	Male	Female	Male	Female	Male	Female	Male
Consanguinity	1° cousins				1° cousins	1° cousins	2° cousins	1° cousins			1° cousins
Growth parameters
Measurements at birth (SD)	3.5 kg (0.81), n/a, 33 cm (−1.22)	3.1 kg (−0.62), n/a, 34 cm (−0.54)	3.1 kg (−0.74), 49 cm (−0.44), n/a	n/a	3.6 kg (+0.08), 56 cm (+2.23), 34 cm (−0.54)	2.8 kg (−1.19), 49 cm (−0.20), 35 cm (+0.11)	3.45 kg (−0.18), 50 cm (−0.06), 34 cm (+0.54)	n/a	3.5 kg (−0.10), n/a, n/a	n/a	n/a, n/a, n/a
Age at last evaluation	7 years	5 years	7 months	17 years	26 months	2 years	18 years 9 months	16 years	10 years 6 months	12 months	7 years
Height (SD)	119 cm (−0.47)	106 cm (−0.36)	67 cm (−0.62)	157 cm (2.10)	n/a	87.5 cm (+0.36)	170 cm (−0.92)	165 cm (+0.43)	130 cm (−1.57)	n/a	116 cm (−1.7)
Weight (SD)	18 kg (−1.75)	14 kg (−2.02)	7 kg (−1.57)	47 kg (−1.91)	n/a	11.1 kg (−0.96)	74 kg (+0.31)	50 kg (−0.50)	38 kg (+0.48)	n/a	20 kg (−1.18)
OFC (SD)	49 cm (−1.96)	52 cm (+1.19)	41 cm (−2.47)	55.5 cm (−0.07)	n/a	47.5 cm (+0.02)	52 cm (−2.09)	46 cm (−6.86)	45.8 cm (−5.52)	41.5 cm (−3.20)	50 cm (−1.50)
Craniofacial findings
Short forehead	+	+	+	+	+	+	+	+	+	+	+
Medially sparse/flared and laterally extended eyebrows	+	+	+	+	+	+-	+	+	+	+	+
Low-set ears	–	–	–	–	–		+	+	–	n/a	+
Ocular abnormalities
Horizontal nystagmus	+	+	+	in infancy	+	–	+	+	+	+	+
Bilateral corneal opacities/corneal dystrophy	+	+	+	+	+	+	+	+	+	+	+
Genitourinary findings/breasts
Absent scrotum/labia majora	+	+	+	+	+	+	+	+	+	+	+
Hypospadias	NA	NA	–	–	+	NA	-	NA	+	NA	-
Tuft of hair extruding from the lactiferous ducts	–	–	–	+	n/a	n/a	+	+	+	+	+‡¥
Neurological features
Global DD/ID	Severe	Severe	n/a	Moderate	n/a	Severe	Moderate to severe	Moderate	Moderate	Severe	Severe
Cranial MRI findings	Cerebellar hypoplasia, Dandy-Walker malformation	n/a	n/a	Cerebellar hypoplasia, Dandy-Walker malformation	Cerebellovermian hypoplasia, optic nerve hypoplasia	Cerebellovermian hypoplasia with pontine involvement	Severe cerebellar and vermian hypoplasia and large parietal cyst	Cerebellovermian hypoplasia with pontine involvement	Cerebellovermian hypoplasia with pontine involvement	Cerebellovermian hypoplasia with pontine involvement	Dandy-Walker malformation
Endocrinological evaluation
Basal testosterone	NA	NA	n/a	n/a	Normal	NA	3.20 ng/mL (2.7–10.7)	NA	0.02 ng/mL (0.07–0.2)	NA	Normal
Basal estradiol	n/a	n/a	NA	NA	NA	n/a	NA	68.55 pg/mL (0–266)	NA	n/a	NA
Response to short stimulation test	NA	NA	n/a	n/a	n/a	NA	Adequate	NA	Adequate	NA	n/a
LH, FSH	n/a	n/a	n/a	n/a	n/a	n/a	4.6 mIU/mL (1.7–8.6) 5.4 mIU/mL (1.5–12.4)	6.13 mIU/mL (1.6–8.3) 3.81 mIU/mL (3–10)	0.03 mIU/mL (0.3–2.8) 0.68 mIU/mL (<4.1)	n/a	Normal
Other
	–	–	–	Heart murmur	Retinal degeneration	Decreased sensitivity to pain	–	–		–	–

*Patients’ phenotypes previously published.13
†Patient phenotype and causative MAB21L1 mutation previously published.12
‡Personal communication with J. Thevenon.
DD, developmental delay; FSH, follicle stimulating hormone; ID, intellectual disability; LH, luteinising hormone; n/a, not available; NA, not applicable; +, present; –, absent.